While there are many childcare resources in the Jefferson County information guides, there is little overlap between the childcare listed in the Jeffer-son County guides and the childcar
Trang 1Figure 6 Education resources: Cognitive mapping vs resource guides
Figure 7 Health care resources: Cognitive mapping vs resource guides
Trang 2County resource guides failed to provide adequate
information Except in education and childcare,
the resource guides fell far short of the number of
resources identified by the mapping participants
While there are many childcare resources in the
Jefferson County information guides, there is little
overlap between the childcare listed in the
Jeffer-son County guides and the childcare identified by
the cognitive mapping The GIS maps effectively
demonstrate such knowledge gaps
Second, there are a significant number of
resources in Denver County (east of Jefferson
County) that providers and clients identify
Rea-sonable accessibility to Denver County, as well as
lack of availability of the resources in Jefferson
County, likely accounts for this trend Building
a community-based SOC will require Jefferson
County to find ways to offer some of these services
locally, a challenge that will require developing
community partnerships to overcome the financial
constraints which the County faces
Third, opposite of the previous trend, Jefferson
County resource guides provide mainly Denver
locations for some types of resources, even though
the same resources exist in numerous places in
Jefferson County Available resources closer to
Jefferson County residents are a fundamental
component of SOC and, in this trend, require only
disseminating the information effectively, which
is a low-cost method to improve community-based
service delivery
Finally, there is a large disparity in knowledge
between clients and providers With the exception
of 3 of the 24 categories, Education, Recreation,
and Commercial Resources, the providers and
clients did not overlap significantly in knowledge
about resources Providers know more about
traditional resources such as other agencies or
governmentally-supported social services, while
clients know about resources of a less traditional
nature, such as churches, motels, and parks where
teenagers gathered to socialize and engage in
recreational sports activities Although these
informal resources are not referral services that
providers typically pass along to clients, they are important community-based resources to share with clients In creating a community-based SOC, providers need to be aware of the alternative methods clients use to meet their needs In some instances, this new information will lead to the creation of government/community partnerships
to more effectively and efficiently deliver services
In other circumstances, the additional knowledge
of resources will provide clients with options and/
or fill gaps in needs that traditional government and community providers cannot meet
Lessons LeArned
Several problems directly and indirectly related
to the GIS component of the project became apparent and required adjustments to the pro-cedures or accommodations to the expected output These include research procedures that are incompatible with social service agencies’ capacity, issues of client confidentiality, repeat rates, incomplete and/or inaccurate databases for coding resource locations, coding protocols, and mapping accuracy
First, as has been found before, many county and local agencies lack leadership that under-stands the value of GIS in policy decision-making (Greene, 2000; Nedovic-Budic, 1996; Ventura, 1995; Worrall & Bond, 1997) Hence, many agen-cies lack the technical ability to employ GIS and, consequently, also lack the understanding to work effectively and efficiently with the researchers Furthermore, because social service agencies typically do not have a GIS analyst on staff, data and map files have limited usefulness beyond the initial analysis as presented in the final report Finally, human service agencies have organiza-tional procedures that create significant barriers
in implementing research projects, barriers that need to be addressed in the project planning stages (Ventura, 1995) Jefferson County Human Services suffered from all three impediments
Trang 3and was exacerbated by the high turnover of the
staff In the first year, two-thirds of the project
staff left By the middle of the second year, only
one person out of nine key project staff remained
Those who left included the project manager and
the principal investigator, both of who had been
replaced twice Within 18 months, none of the
people who conceptualized and wrote the HHS
grant were involved in the project Institutional
memory was wiped clean and new staff was
unfamiliar and wary of many components laid
out in the grant proposal, including the
untra-ditional resource identification method Higher
administrative support for the innovative project
waned, and “business as usual” reasserted itself
as the dominant paradigm It became clear that
the resource database developed through the
map-ping process would not be updated on a regular
basis and, perhaps, not disseminated throughout
the organization if left to Jefferson County The
CIPP sought out a more stable organization to
house the resource data, Colorado 2-1-1, with the
permission of the first project manager
Second, human service agencies as well as
educational institutions cannot share
client/stu-dent data This presents a significant research
barrier when the project requires participation
of these populations Ideally, individuals within
the organizations would have both the access to
the data and sophistication to manipulate the data
in accordance with standard research protocols
This is unlikely to be the case in institutions which
are financially strapped and lack the vision or
political will to invest in trained personnel and
needed research tools To ameliorate these
condi-tions, project planning must include agreed-upon
protocols for effectively and efficiently handling
confidential data
Third, unique to this project was the
cre-ation of a “repeat rate” to set a standard for data
density The 80% repeat rate was selected for
efficiency of resources, based on an
extrapola-tion of the average number of points per map
and time needed to code and enter the data for
each map Unknown was how many participants/maps were needed to reach the 80% repeat rate
in each of the 24 categories Initially, the CIPP recommended target was 450 participants This number was revised downward by Jefferson County Human Services to a maximum of 250 participants From the 247 actual participants, the 80% repeat rate was reached in only two of the
24 resource categories The average repeat rate was 55% across all categories, indicating that more than 250 participants were needed to reach 80% Whether 450 participants were ultimately required is unknown More importantly, did the lower repeat rate significantly affect the quality
of the project? Certainly, fewer resources were identified at the 55% rate; but 1,480 resources not
in Jefferson County resource guides were fied; not an insignificant contribution to building
identi-a more comprehensive sociidenti-al services
Fourth, in the process of coding the maps and sorting the data to find repeated addresses
or groupings by type of provider, and so forth, it was discovered that precise alphanumeric coding was critical With the large number of data fields (attributes) assigned to each participant, there were inconsistencies in some of the categories The data cleaning was more extensive than anticipated Future projects should utilize numeric coding in attributes to the fullest extent possible and develop strict alphanumeric standards for addresses, or-ganizational names, and other alpha fields.Finally, to find resource addresses, MapQuest and the Denver metro area phone book were used MapQuest was the most efficient method but had the most errors, as discovered when the address was imported into ArcMap A cross-check with the phone books corrected most of these errors.Nine percent of the mapping points were unidentifiable due to a combination of missing information in MapQuest and the phone book, and poor location information on the hand drawn maps The latter accounted for a greater proportion of the unidentified points, especially resources such
as neighborhood parks and unnamed resources
Trang 4such as “soup kitchen.” Rather than rely solely
on participants naming the nearest cross streets
to such resources, the closest known commercial
entity should be identified This redundancy will
reduce missing data due to participant error in
naming streets
f uture t rends
While this project was limited to identifying
resources, spatial patterns of resource locations,
and knowledge gaps, the collected data can be
mined further More specific uses can be created,
such as a searchable Web-based provider resource
database and the identification of physical and/or
service areas with inadequate resources in relation
to socio-economic deprivation areas The latter
allows providers to demonstrate specific needs,
important for several reasons, including the pursuit
of future programmatic funding These specific
uses are described in greater detail as follows:
the Web-based database can be converted
into a tool for social service providers to
identify available resources and the most
accessible locations for clients (Worrall &
Bond, 1997) The end user (a case-worker)
would be able to search for particular
re-sources based on any number of criteria or
a combination of criteria For example, one
might enter necessary criteria such as Rental
Assistance Housing Resource located within
three miles of a given location that also
caters to Spanish-speaking clientele After
these attributes or criteria are entered into
the appropriate locations on the Webpage,
a list of all the resources or providers that
fit the criteria could be retrieved, similar to
the business name search feature available
through a site such as MapQuest Finally,
digital maps could be generated with driving
directions for the case-worker to print out
for the client It is also possible to map the public transportation routes to services
used to conduct comprehensive, able, and defensible needs assessments A social service provider administrator or grant writer could search the data described above in conjunction with Census data and the County’s client locations to reveal areas
quantifi-of need or areas quantifi-of excess (Bond & Devine, 1991; Worrall & Bond, 1997).6 A strategic plan could be developed to determine where
a new office or access point for a particular resource should be located to serve the great-est number of clients This type of spatial analysis based on quantifiable numbers and distances can be used to justify a particular course of action either for internal/external accountability or to acquire funding for vari-ous projects aimed at community resource and social service distribution
Acknow Ledg Ments
The author would like to thank April Smith, Department of Psychology, Colorado State Uni-versity, and Mary Tye, Department of Psychol-ogy, Colorado State University, for running the workshops and coding the data; David Wallick, Colorado Institute of Public Policy, Colorado State University, for conducting the GIS analysis; and Juliana Hissrich for providing administrative support to the project
c onc Lus Ion
Cognitive mapping combined with GIS analysis
is a powerful method for identifying community resources by providing: (1) a comprehensive database of existing services; (2) a basis to build communication networks and cooperation among government and community providers; (3) the
Trang 5ability to create an efficient system that avoids
duplication of efforts; (4) an understanding of
the geographical distribution of resources; (5) the
identification of resources lacking in the county
and specific communities; and (6) knowledge
differences among diverse participant groups
The addition of 1,480 resource locations within
the seven study areas (only a portion of Jefferson
County) nearly tripled the number of resources and
services listed in the Jefferson County guides
Ultimately, service delivery in SOC is about
building partnerships across the multiple services
and bringing in new, even sometimes
untradi-tional, community partners Family involvement
is the key in this collaborative arrangement
Similar to untraditional community partners and
resources, families as partners do not fit easily
within current social service delivery structures,
values, and beliefs Recognizing, valuing, and
partnering with resource providers identified by
clients and community members is one important
step toward shifting practices Cognitive
map-ping with GIS provides a tool for taking the first
critical steps
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Trang 71 The project was supported by grant
#90CA1715/01, CFDA #93.570 from the
Federal Department of Health and Human
Services through Jefferson County,
Colo-rado
2 The term cognitive mapping is used for a
va-riety of techniques, including “fuzzy
cogni-tive mapping,” a technique that builds mental
maps of perceptions from focus-group and
interviews (Hjortso, Christensen, & Tarp,
2005; Hobbs et al., 2002) In this project,
cognitive mapping means hand-drawn
maps of tangible community resources and
locations, a geographical data collection
technique new to GIS
3 Nine percent of the mapping points could
not be accurately located and were dropped
from the analysis Of the remaining 89%,
two possible location errors could occur in
transferring the cognitive map information
into a database for ArcMap First, multiple
coders could use different alphanumeric
codes, thereby making the same resource
appear as a different resource To correct
this error, the data was cleaned by
conduct-ing sorts on multiple columns in the excel
spreadsheet to reveal unknown duplicates
For example, a search on “Research Name”
might find the same resource with
inconsis-tent address codes If the address did not
match exactly (e.g., one was coded with
“St.” and another coded with “Street,” the
coding was corrected to be consistent
Simi-lar searches were done on other categories
such as street address, street name, and zip
code The data was cleaned accordingly The
second error was from incorrect addresses
in the MapQuest and/or Dex directory The
Dex directory is the official metropolitan
phone and address directory and should have
a high level of reliability; however, the actual
reliability rate is unknown To correct for possible errors, all identified social services not in the Jefferson County resource guides (e.g., soup kitchens, English as a Second Language courses, support groups, etc.) were called to verify the address It was assumed that the Jefferson County resource guides had accurate information
4 All identified resources were provided
to Colorado’s 2-1-1 system, which is the national abbreviated dialing code for free access to health and human services infor-mation and referral (I&R) 2-1-1 is an easy-to-remember and universally-recognizable number that makes a critical connection between individuals and families in need and the appropriate community-based organiza-tions and government agencies Housing the data with 2-1-1 allows statewide access to resources and bi-annual updating to keep the information current Colorado 2-1-1 system
is the depository for the resources collected
in this project Web searchable database of resources can be found at http://211colorado.org/
5 CIPP provided Jefferson County with the ethnic enclave areas based on the 2000 Census The Asian communities fell out-side the project boundaries set by Jefferson County (see Figure 1) and, unlike Russians, Latinos, and Native Americans, Jefferson County did not request mapping with the Asian community
6 For example, it might be found that 65% of all users of a certain type of resource (this data would be collected by cognitive map-ping alone) live “x” number of miles away (analysis performed by the GIS system) from
a particular needed or frequently-accessed resource (gathered through cognitive map-ping and other sources)
Trang 8Append IX
Only forty percent of the participants provided
demographic information, which limits the
ability to determine the gender, age, and
ethnic-ity/race of the participants However, there is no
way to determine the representativeness of the
sample on these traditional demographics since
the population characteristics are unknown
Table 2 Demographics of participants (n=100)
Demographic
characteristic All participants(n=100) Providers(n=19) Clients(n=72) Community Residents (n=9)
Number and percent
a concern For the identification of resources, a cross-section of the types of people who use or provide services and the geographical distribution
of their knowledge was most important, of which both criteria were met
This work was previously published in Emerging Spatial Information Systems and Applications, edited by B Hilton, pp
326-350, copyright 2007 by IGI Publishing (an imprint of IGI Global).
Trang 9Chapter XLV
Collaborative Mapping and GIS:
An Alternative Geographic Information Framework
Edward Mac Gillavry
Webmapper, The Netherlands
Abstr Act
The collection and dissemination of geographic information has long been the prerogative of national mapping agencies Nowadays, location-aware mobile devices could potentially turn everyone into a mapmaker Collaborative mapping is an initiative to collectively produce models of real-world loca- tions online that people can then access and use to virtually annotate locations in space This chapter describes the technical and social developments that underpin this revolution in mapmaking It presents
a framework for an alternative geographic information infrastructure that draws from collaborative mapping initiatives and builds on established Web technologies Storing geographic information in machine-readable formats and exchanging geographic information through Web services, collaborative mapping may enable the “napsterisation” of geographic information, thus providing complementary and alternative geographic information from the products created by national mapping agencies.
Introduct Ion
Since the Enlightenment, mapping and the
pro-duction of geographic information have been
institutionalised: the map is the power At home,
maps were used as an instrument for nation
building as nation states emerged: a
legitimi-sation device (McHaffie, 1995) People learned
about their country and administrations needed
a tool to govern the territory Away from home, maps were an instrument for colonisation, when Africa and Asia were split among the European nation-states
During the last few decades, there has been rapid democratisation of geographic information and maps Sawicki and Craig (1996) distinguish
Trang 10three ways in which this movement is apparent
First, the locus of computing power and data access
is broadening Second, the level of skills to turn
raw geospatial data into geographic information
has become less demanding Third, the locus of
applications has moved closer to the citizenry
Geographic information systems moved from
mainframes and the UNIX operating system onto
personal computers and the Windows operating
system From research and government, GIS
spread into the business sector The PARC Xerox
Map Server and Virtual Tourist brought maps to
everyone’s PC in the late 1990s, followed by online
map Web sites such as MapQuest and Multimap
In 1997, Brandon Plewe noted that “the Internet
holds promise for exponential increases in the
efficiency and effectiveness of the ways in which
we obtain, use and share geographic information
in all its forms” (Plewe, 1997) In July 2002, 7.1
million European users visited one of the many
online map Web sites (Nielsen//NetRatings,
2002) Google Maps, introduced in February
2005, reached almost 1.7 million visitors in that
month (Buchwalter, 2005)
Although maps are more widely used than ever,
the production of geographic information, and
especially mapping, is still highly concentrated
among national mapping agencies and the GI
in-dustry But this oligarchy is soon to be dissolved,
for we see the third aspect of the democratisation
of geographic information–the locus of
applica-tions moving closer to the citizenry–becomes
apparent now that location-aware mobile devices
are coming within everyone’s reach GPS units
are not only available to surveyors anymore, as
cheaper devices are sold for outdoor recreation
Also, small GPS antennae can communicate
with other devices over Bluetooth, and there
are already mobile phones and personal digital
assistants (PDAs) for the consumer market that
have GPS-chips built in
At the same time, digital maps have become
portable Various mobile phone operators have
started to deliver location-based services to mobile
devices Mobile phones come with route planning applications, thus making in-car navigation sys-tems redundant Maps are not only delivered to the desktop, but also to mobile phones and PDAs, requiring new visualisations as the screen size, resolution, and use patterns differ significantly Collaborative mapping is an initiative to col-lectively create models of real-world locations online that anyone can access and use to virtually annotate locations in space (McClellan, 2003) The value of the annotations is determined by physi-cal and social proximity, the former expressed
in distance, the latter in “degrees of separation.” Thus, the informational value and the pertinence
of spatial annotations is not only dependent on physical distance, but also dependent on the trust relationship between individuals or groups
of people through social networks: the “Web of Trust” (Espinoza, Persson, Sandin, Nystrom, Cacciatore, & Bylund, 2001)
However, there is a discrepancy between cal and social proximity Privacy and personal freedom become highly important issues when one’s location is related to their social behaviour
physi-On the other hand, the fear of surveillance that accompanies positioning is already gradually reducing in society (Ahas & Mark, 2005) Fur-thermore, this discrepancy can be mediated by users themselves by storing annotations and tracks locally, thus creating distributed repositories, and by explicitly setting the level of privacy on each of these annotations and tracks Finally, users themselves remain in control of their so-cial identification–their preferences and social network–while they make use of collaborative mapping services, whereas, for example, the so-cial positioning method aggregates these social characteristics to study the space-time behaviour
of society (Ahas & Mark, 2005) Collaborative mapping services are therefore less pervasive in the privacy of their users because users negotiate the trade-off between the benefits of the service and their privacy concerns
Trang 11Collaborative mapping is to location-based
services (LBS) what blogging is to the Web: a
mechanism for authoring one’s own
location-based experiences (Bleecker, 2005) The notion
of “social proximity” as a measure of relevancy
of geographic information sets collaborative
mapping apart from corporate LBS-providers
Requesting the nearest Italian restaurants, the
service not only takes into account the distance
to the restaurant from the current position of the
user, but it also navigates his/her social network to
find a suitable result People are willing to travel
farther because the particular restaurant is a
favou-rite haunt of one of their relations Furthermore,
geographic information is not merely broadcast
to users, but users can actively contribute to the
service: geographic information flows back to
the service A collaborative mapping service
then works like a spatially enabled notebook or
message board, depending on the privacy settings
people attach to their postings
Collaborative mapping may even become a
vehicle for community-based participatory
plan-ning As users share their thoughts, opinions, and
ideas about physical places, local knowledge,
community needs, and specific social histories
may thus be appreciated and incorporated into
the process (Harris, Weiner, Warner, & Levin,
1996) In this way, the necessary information
is produced in an operation whereby the local
knowledge arising from the social narratives, the
mental map, is converted into data within a GIS
for research and policy formulation
This chapter aims to describe the various
developments that have led to the necessity and
feasibility of collaborative mapping Based on
current practice, it goes on to describe an
ap-proach for an alternative geographic information
infrastructure that draws from collaborative
mapping initiatives and builds on established
Web technologies
bAckground
f ree g eographic data
Collaborative mapping as a practice to create geographic data was born out of the lack of af-fordable and copyright-free geographic data Governments spend billions to create large-scale geographic data to fulfill their civil and military responsibilities, and only governments can afford the hardware and software, as well as the labour costs of trained personnel involved in creating large-scale geographic data (Harris et al., 1996) Nevertheless, geographic data created by US government agencies such as the US Geological Survey (USGS) and the Census Bureau is avail-able copyright free and made available at the nominal cost of copying it, whereas in most other countries, geographic data has to be paid for and
is subject to strict copyright laws
Since the market position of national mapping agencies (NMAs) is changing rapidly, their bud-gets being cut and status changed, their geographic databases have become their main capital assets
In the new economy, the digital elevation model and digital line graphs are the new currency (McHaffie, 1996) To survive in their new role, they have to protect their assets with copyright restrictions and inhibiting pricing structures Whereas other government agencies and academic institutions in these countries obtain geographic data at a discounted rate, nonprofit organisations, (small) businesses, and individual citizens have found these protective measures inhibiting Not only pricing and copyright put up barriers As the
GI industry is evolving rapidly, patents have been granted to various key players in the market This practice is a delicate trade-off between encour-aging innovation and encouraging monopolies Collaborative mapping has therefore become
a practice to create copyright-free geographic data for free and to bring together existing freely available sources of geographic data
Trang 12Positioning Technology
There are various developments that have
facili-tated the viability of collaborative mapping First
of all, the democratisation of mapping has not only
brought maps to everyone’s desktop or hand-held
device, the availability of positioning technology
contributes to this trend as well GPS devices
used to be the domain of surveyors and geodetic
engineers, but nowadays there are many cheap
GPS devices available for outdoor enthusiasts,
which become smaller and smaller As of 1 May
2000, selective availability has been turned off
so public users can locate themselves using GPS
with “military precision.”
With Bluetooth, separate GPS devices
commu-nicate with palmtops and mobile phones Recently,
there are palmtops and even mobile phones that
come with a built-in GPS antenna Furthermore,
the Enhanced 911 (E-911) US federal mandate
requires mobile phone operators provide precise
location information of mobile devices within 50
to 300 meters The ability to establish one’s
loca-tion is unprecedented The data that is obtained
from location-aware devices indicates the actual
location and movement of people, with increasing precision in real-time (Ahas & Mark, 2005).These location-aware devices turn everyone into a producer of geographic information, thus bridging the cartographic labour process Ever since the first differentiation of cartographic labourers that occurred with the invention and adoption of the printing press, when compila-tion and reproduction of the map were separated (McHaffie, 1996), mappers are “slogging” into the messy reality of the field again in order to produce the “map.”
Location Awareness
Publishing on the Web has changed over the last few years There is no need to have your own Web server or even know how to code HTML: nowadays everyone can publish on their Weblog These Web based publications consist primarily
of periodic articles in reverse chronological order Admittedly, most early Weblogs were updated manually, but tools to automate the maintenance
of such sites made them accessible to a much larger population
Figure 1 Various trends drive the uptake of collaborative mapping
Trang 13Not only Weblog authors (bloggers) writing
about similar topics started to form communities,
but there also started to appear listings of Weblogs
that were from the same country (e.g., the now
defunct Gblogs) or even located in the same city
(BrightonBloggers) The next step came when
NYCBloggers (http://www.nycbloggers.com/)
and London Bloggers (http://londonbloggers
iamcal.com/) started indexing bloggers by their
nearest subway stop or tube stop respectively
Mapping the virtual space of the blogosphere on
to the physical one, these listings put a sense of
place back into cyberspace
In a final step, the positional accuracy increased
from country, town, and subway stop to the level
of geographic coordinates, while the geographic
extent increased to cover the world with GeoURL
(http://geourl.org/) Bloggers are encouraged to
add HTML meta tags to their Web pages to inform
visitors about their location:
<meta name=”ICBM”content=”52.09022,5.08159”>
<meta name=”geo.position”content=”52.09022;5.0
8159”>
<meta name=”DC.title” content=”Webmapper: what
the map can be.”>
GeoURL then spiders the Web and indexes
Weblogs that have these meta tags, and puts pins
on the world map indicating the locations of all
the Weblogs Some bloggers travel regularly, and
Weblogs can be updated using mobile devices,
so-called moblogging Location thus becomes
another means to structure Weblog entries Also,
bloggers frequently write about locations they
are visiting Developers have created extensions
for popular blogging tools such as Movable Type
for authors to attach a location to their Weblogs
and individual postings, and to keep track of
their travels, nearby Weblogs, and the locations
of their visitors Other tools such as IndyJunior
(http://www.bryanboyer.com/indyjunior/) and
World66 (http://www.world66.com/) allow
bloggers to show their travels and the countries
visited The World as a Blog (http://brainoff.com/geoblog/) shows the locations of recently updated Weblogs All in all, Weblogs have certainly raised the awareness of location as a means to structure information sources
Online Communities
Online communities have been around since the start of the Internet More and more, it is not only important to advocate that you belong to a certain community, but also who you know in various communities Search engines rate Web sites based upon the number of hyperlinks that link to a Web site Online social networks started appearing
in 2002, when the term was used to describe the means of networking in virtual communities, and became popular in 2003 with the advent of Web sites such as Friendster, Tribe.net and LinkedIn While Friendster allows members to chart their network of friends, LinkedIn aims at profes-sionals to keep track of their business contacts The popularity of these sites rapidly grew, and major companies have entered the Internet social networking space
Whereas these online social networks require visitors to subscribe to a particular network before using the service, and people end up subscribing
to all these Web sites, thus becoming a member
of all separate networks XFN and FOAF are distributed networks People define their own networks and can identify their online friends and the nature of their relationship As FOAF is based on RDF, it can be mixed with other RDF vocabularies, so resources can be shared among networks of people Thus, sharing information among a group of people based on the nature of relationships is a feasible thing
Open Source GIS
The final trend contributing to the birth of laborative mapping is the adoption of open source
col-in the field of GIS The IT col-industry has a long
Trang 14history of open source projects, from
operat-ing systems, Web servers, and programmoperat-ing
languages to applications Only recently, the GI
industry is catching up, with open source
data-bases that support spatial features, for example,
MySQL and PostGIS There are several libraries,
for example, to convert between common spatial
data formats, or to change projections that are
included in various open source projects GRASS
has become a well-known open source desktop
GIS For online GIS applications, there are
vari-ous open source Web-mapping servers such as
Deegree, GeoServer, and the UMN MapServer
Web clients such as Chameleon and ka-Map
al-low developers to build compelling interfaces
to work with maps in your Web browser Most
of the architectures are built around OGC (open
geospatial consortium) standards such as the Web
Feature Server and Geography Markup Language
specifications
Online vector-based mapping used to be the
domain of proprietary plug-ins from leading
GIS vendors As the XML-based scalable vector
graphics (SVG) file format gains popularity,
vec-tor-based mapping is not anymore the monopoly
of the GIS industry and government agencies
Many individual Web developers have started
to create compelling vector-based Web-mapping applications
With geographic data being transferred based upon open standards and clear interfaces, it is easy for developers to combine various data sources and make interesting Web-mapping applications, with no resources spent on buying software
c o LLAbor At Ive MAppIng
Several projects are underway to collect graphic data for the creation of base maps Amsterdam RealTime (http://www.waag.nl/re-altime/), conceived as an art project, has been a trigger for many people to realise the potential of collaborative mapping As part of an exhibition
geo-on historical maps of Amsterdam in late 2002, visitors were invited to participate and take a GPS device with them for a week During that time, their locations were uploaded in real time to a Web server and beamed onto a screen in one of the exhibition rooms Visitors of the exhibition saw a new map of Amsterdam gradually appear
as the individual GPS tracks joined up and started
to overlap
Figure 2 The iterative collaborative mapping process consists of four steps
Trang 15These base maps typically consist of road
networks in urban areas that have been traced
moving around the area with a GPS device Most
community mapping projects seem to follow
four steps: collection, editing, augmentation,
and distribution (Walsh, 2005) In the following
paragraphs, these steps of community mapping
projects are discussed Although the paragraphs
are provided in this sequence, community
map-ping is an iterative process The steps are regularly
iterated as new data becomes available, and these
steps may take place concurrently
c ollection of base Map data and
gps t racks
There are several ways to kick-start a
collabora-tive mapping project One approach is to scan
and georeference out-of-copyright paper maps or
global satellite imagery, and incorporate these as a
background to provide a geographic context for the
project The advantage of global satellite imagery
over scanned paper maps is the flexibility in the
projection Opting for scanned paper maps, there is
not this flexibility, as the map image may become
distorted when changing the projection
Another approach is to use readily available
vector-based geographic data, having the
flex-ibility of projecting the data while
maintain-ing the sharpness of vectors For example, the
TIGER/Line data from the US Bureau of the
Census provides a good source for geographic
data to start a community mapping project As
discussed previously, copyright restrictions may
prevent projects from incorporating these sources
For the Mumbai Free Map project (http://crit.org
in/projects/gis), the Collective Initiative Research
Trust (CIRT) builds the base map from the
cu-mulative basis of the urban research, design, and
development studies and interventions conducted
previously by CIRT Thus, CIRT develops an
open-access spatial data infrastructure, and a
set of simple tools and applications localised in
Indian languages, for knowledge transfer and
participatory urban planning by communities and citizens in Mumbai
The third approach to collect base map data is the most labour intensive This low-level approach requires a large group of community members to travel the area to be mapped with a GPS receiver, and follow the tracks, paths, and streets to trace the network On their travels, members may add additional waypoints for landmarks in the area Returning from these surveys, the community members upload their GPS tracks over the Web
to a central server, or equally make their tracks available online for others to harvest Previously collected GPS data created while engaging in a game of geocaching or as a form of GPS-drawing, can be equally made available for integration
In the United Kingdom, GPSdrawing (http://www.gpsdrawing.com/) uses a GPS receiver to make pictorial drawings while moving around Conceived as an art project, base mapping is not the objective here, but the accumulation of GPS tracks makes a nice base map Geowiki (http://www.geowiki.com/) is a cartographic variation
of the interactive encyclopaedia Web site, pedia GPS tracks are converted into PostScript files that are merged, using a drawing package, into a GIF file that is put on the Web site Apart from showing the road networks in some of the larger towns in Britain, the Web site allows visi-tors to enter information about pubs and shops, with personal reviews
Wiki-Whereas Geowiki uses a rather onerous production process to convert the GPS tracks into a base map, recent initiatives build on the MapServer Open Source WebGIS package to serve online maps on the Web The MapServer was set up in compliance with standards from the OGC, particularly the Web feature server with transactional extension (WFS-T) to support not only serving maps on the Web, but also to edit the maps remotely The London Free Map (http://uo.space.frot.org/freemap/) initiative finds pedestrians, bikers, and skaters in London volunteering to collect GPS tracks Of course,
Trang 16these data are difficult to integrate with the road
networks for car navigation, as these tracks are
not representative for cars However, as personal
navigation becomes more important, it is useful to
have navigation systems that include cycle tracks
and walk paths The London Free Map cooperates
closely with the Open Street Map (http://www
openstreetmap.org) initiative Steve Coast bikes
around London carrying a GPS device (Dodson,
2005) Coming home, he downloads the GPS
tracks onto his laptop to subsequently make them
available online to share the tracks with others
Street by street, a copyright-free map of London
is built
Editing Waypoint Data
This step involves the actual creation of the base
map from the raw GPS tracks previously
col-lected First, it has to be decided which tracks
or individual GPS points to consider for
inclu-sion in this step Next, geometric and statistical
algorithms have to be applied to decide when
several very close lines are actually the same
line and thus need to be averaged together, or are
actual parallel segments Intersections have to
be modelled into junctions at which tracks have
to be split in segments to ensure topology Other
points may belong to traffic situations such as
squares, roundabouts, and parks
Quantitative mechanisms relying on geometric
algorithms, or qualitative mechanisms requiring
human intervention, may decide which GPS tracks
are relevant at this stage in the process Geometric
algorithms may filter out GPS points that have
a significantly different accuracy from the rest
This may be important in areas with bad satellite
reception such as urban canyons, or at the start of
a GPS track due to cold start: sometimes it takes
rather long for a GPS device to establish
connec-tion with an appropriate number of satellites
Equally, GPS points, tracks, or repositories can
be included or excluded from the GPS tracks that
are the input for the base map based on
qualita-tive mechanisms (Shorter, 2005) There may be
a hierarchy of users, with trusted users given a higher moderation status based on the quality of their contribution to the community, to review contributions To ensure community members remain interested and help reviewing, RSS feeds
of latest updates and additional repositories of GPS data can be made available to trigger people to help moderate the GPS tracks Moderators and com-munity members can discuss among themselves about the value of GPS repositories on discussion forums that are provided at a central server, or that can be left as comments on distributed repositories and be amalgamated using RSS readers
As a save approach, GPS data is not able for postproduction editing unless one com-munity member has reviewed the contribution The strength of collaborative mapping is that relationships within the community can be made explicit Therefore, members may only want to include GPS tracks and landmarks in their base map that were left by people within their personal network of friends Finally, previous moderations
avail-of the GPS data remain available for revision avail-of the individual member, and they can roll back moderations on request, just like a wiki
Edelkamp and Schrödl describe a “map ment process” to create a traversable road network from GPS tracks (Edelkamp & Schrödl, 2003)
refine-In the context of normalising and synthesising GPS tracks, the road segment clustering stage and the road centreline generation stage of the map refinement process are relevant The road segment clustering stage identifies segments that are common between different GPS tracks and locates intersections of these segments, based on the contiguity information and temporal order of the GPS points The road centreline generation cre-ates a geometric construct that captures the road geometry The centreline is generated from a set
of GPS points using a weighted least-squares fit The relative weight of each GPS point is derived from the measurement error, which is usually available from the GPS receiver
Trang 17Annotation of Geometry with
r eal-w orld semantics
This step ensures the geometry of the network
makes sense for people that use the network to
locate themselves and navigate around the area
The driving restrictions at one-way streets and
turning restrictions at the intersection of segments
have to be added by ground truthing: surveying
the actual location to interpret the data correctly
Surveyors go out with a printed base map to
an-notate and upload annotations at a later time, or
may well carry PDAs connected to a WFS-T map
server and add annotations on the fly
The Downhill Map of Bristol
(http://locate.ira-tional.org/bristol_map/) is a map for
skateboard-ers, cyclists, and walkers Artist Heath Bunting
and the Bristol Skate Survey group surveyed the
streets of Bristol, the road surface quality, and
the locations of fruit trees Like Geowiki, the
Downhill Maps of Bristol incorporates landmarks
along the street network created This initiative not
only simply records the longitude and latitude, but
also maps the attributes of the map object such as
height and road surface quality From this data, a
functional online route planning service can be
created for cyclists, skateboarders, and skaters,
which no national mapping agency would be able
to offer (Albert, 2004) The Dutch GeoSkating
project (http://www.geoskating.com/) aims to
cre-ate a similar map of the outskirts of Amsterdam,
uploading the GPS tracks and notes on road surface
quality to a Web server in real time
Not only navigation attributes such as road
type, turn restrictions, and one-way streets are
col-lected in this step, but also toponymy is important
here: the geographic names of roads, streets, and
landmarks In the context of collaborative mapping
projects, geographic names are collected using
the notion of “consensus-based location,” a term
coined by Alasdair Turner at the PLAN meeting
in London, early 2005 The name of a location is
established through consensus among a group of
people It is not determined a priori, but evolves
as people in a community add new annotations
in response to the needs of the moment
For example, in the GeoNotes service noza et al., 2001), a “location tag” determines the exact location of an annotation in the service in case the accuracy of the positioning technology of either the creator or the reader is too coarse Thus, other users can still verify the correct location of the note without having to rely on the accuracy
(Espi-of the positioning technology Furthermore, the positional accuracy of the location tag may evolve with improving positioning technology, and de-pending on what labels are defined
The communal character is emphasised as these location tags are shared in the community The set of location tags is stored in the service for other people’s perusal Upon tagging a note with a location, other notes in the vicinity are scanned for their location tags, and presented
as a list of options for location tags, sorted cording to popularity The creator selects a tag from the list or creates a new location tag This service may be bootstrapped with predefined labels taken from gazetteers, the yellow pages,
ac-or tourist databases
This strategy not only applies to point tions, but to streets segments and areas as well The Neighborhood Project (http://hood.theory.org/) uses the TIGER/Line US Census data for mapping city neighbourhoods based on the col-lective opinions of Internet users Addresses and neighbourhood data collected from housing posts
loca-on Craigslist are translated into latitude and lloca-on-gitude values and drawn on the map The blobs
lon-on the map thus give a notilon-on of the spatial extent
of neighbourhoods derived from the collective mental map of Internet users
Distribution
Once the geometry of the street network and the locations of landmarks have been created, they have to be made available to a wide audience, without copyright or financial restrictions In the
Trang 18previous steps, various projects were highlighted,
with the aim to build geographic databases along
While they may coexist to make up a distributed
repository of GPS tracks, it may be advisable
to cooperate, to ensure GPS tracks from these
repositories can be easily incorporated into any
of the other repositories,and base maps can be
exchanged without any problem Therefore, it
is advisable for these projects to work together,
but also to transcend boundaries and work with
other initiatives that may benefit from geographic
data, for example, civic initiatives Already, the
London Free Map, Geowiki, and OpenStreetMap
are cooperating to build a street network for
London together
There are various sets of geographic data
cre-ated as part of a collaborative mapping project The
scanned and georeferenced base maps, the global
satellite imagery, incorporated as background,
can be made available, as well as the geographic
vector data For example, the London Free Map
initiative hosts various BitTorrents to distribute
free geographic datasets in a cost effective way
Also, the individual GPS tracks collected during
the project can be made available as GPX files, a
lightweight XML grammar to express GPS data,
or encoded using the geography markup language
(GML) published online as a Web feature service
(WFS) Also, for applications that do not require
the original vectors, raster images of the street
network can be published as a Web coverage
service (WCS) that can be used as tiles to plot
other data on top of
Challenges and Opportunities
Sawicki and Craig (1996) identify two
contra-dictory currents in information technology that
equally apply to collaborative mapping services
On the one hand, there is a movement towards
more accessibility by more users: online mapping
has experienced a steady uptake, and more and
more people turn to Web maps to find their way in
the real world Also, mobile phones and PDAs are
becoming new platforms for delivering geographic information Since the mid-1990s, more than 50%
of the citizens of the developed countries have become owners of mobile phones, while mobile communication has also been remarkably success-ful in poorer countries (Ahas & Mark, 2005) On the other hand, there is a movement towards less accessibility Although more users have access
to more data and information, the entry cost of the education, training, capital cost, time, and experience of the users to take advantage of in-formation technology is becoming much greater (Sawicki & Craig, 1996) As an example of this movement, Ahas and Mark (2005) write that the uptake of LBS has slowed down, as the services proved too difficult for the public to obtain, and users have difficulties imagining the potential of spatial information For collaborative mapping initiatives to become successful, it is advisable
to start off with the lowest common technical denominator, but to design and develop architec-tures to cater for more advanced technology in the future as location-aware devices become cheaper Already, projects such as the London Free Map use Web-based open source GIS technology and cheap GPS-devices rather than location-aware mobile technology
Since the information value and pertinence
of collaborative mapping services is ised not only by physical proximity, but also by social proximity, participation becomes another challenge when only a small group has access
character-to location-aware, mobile devices Especially in the case of applying collaborative mapping as a form of community-based participatory planning (Harris et al., 1996) or as a means to obtain data for the social positioning method as input for urban planning (Ahas & Mark, 2005), one has to
be aware that it is only based on the space-time behaviour and mental map of only a small group within society, with specific social identifica-tions The dependency of collaborative mapping services on social proximity may well expect a wider participation, as indicated by the popularity
Trang 19of online social networking tools, thus possibly
pushing the uptake of LBS in general
Current collaborative mapping initiatives
rely on GPS-devices to capture road network
geometry and open source GIS technology to
serve maps and edit the raw data The ubiquity
of location-aware devices will increase over the
next few years Not only will the pool of possible
volunteers to participate in collaborative mapping
projects therefore expand accordingly, but the
collaborative mapping process will also benefit
from these technological advances as more raw
positional data is being captured with increasing
accuracy and in real time (Ahas & Mark, 2005)
Finally, the distributed nature will be reinforced,
as more collaborative mapping services will
de-rive spatial annotations from more repositories,
and will have to take into account wider social
networks when establishing the pertinence of
these annotations
Future Trends
Ben Russell (2003) suggests a “street server” as
a vehicle for distributed collaborative mapping
Street servers can be thought of as a computer
network with both private and public functions
for a community of residents of a street In the
context of collaborative mapping, these street
servers operate as a GPS tracks database that
can be linked with other street servers to form a
map covering a wider area, as far as GPS tracks
match up Thus, mobile devices ask stationary
street servers about their position and how to
travel around the neighborhood This network
approach contrasts with the current practice of
serving GPS tracks from a single, centralized
Web server
As geographic information is created
col-laboratively, people upload their annotations to a
central repository, or store their annotations and
tracks on their personal Web sites, thus creating
a distributed framework for sharing geographic
information With increasing storage capacity of
mobile devices, people may even put their GPS tracks on their location-aware mobile devices and share the data with their peers in their social net-work, just as digital music files are shared online
or made available as podcasts Ed Parsons, CTO
of the Ordnance Survey, spoke in an interview about the “napsterisation” of geographic informa-tion, claiming that “the experience of the music industry may also apply to geographic informa-tion” (Westell, 2003)
Thus, as people roam around the city, their mobile devices pick up blocks of geographic data
to locate themselves and navigate the area rounding them That geographic data represents the street network and landmarks of the city blocks where they find themselves, as derived from col-laboratively collected GPS tracks
sur-c onsur-c Lus Ion
Collaborative mapping is the latest development
in the democratisation of geographic information The proliferation of positioning technology, loca-tion-awareness, online communities, and open source GIS technology have paved the way for people being able to contribute geographic data and access localised information Various collab-orative mapping projects are currently collecting GPS tracks to derive street network data The framework of steps described in this chapter was based on experiences from these projects, and will stimulate the exchange of geographic information among these projects Hopefully, collaborative mapping will become a complimentary input for corporate location-based services
r eferences
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Trang 21Introduct Ion
Recent studies have revealed that over 80% of
local governments in the U.S have locational
references in their data (Nedovic-Budic & Pinto,
1999) and a majority of local governments use
geographic information systems (GIS) technology
to manage spatial data, a trend often described as
a “growth surge”(Warnecke, Beattie, Cheryl, & Lyday, 1998) With the growth of Internet, there
is an increasing demand for location specific data and analytical solutions requiring GIS to locate
Trang 22and integrate multiple databases This, in turn,
requires federal, state, and local government
agencies to develop capabilities so that their data
can interoperate For example, a real estate
entre-preneur, looking for a suitable location for a new
business, would require data that combines GIS
data with that of the local government’s zoning
and tax incentive areas Home owners and home
buyers, looking for information about
environ-mental hazards, can use e-maps that combine
data from several sources including the EPA’s
environmental data, and the HUD’s (Department
of Housing and Urban Development) housing
community programs (GAO, 2003) Similarly, a
water/sewer storm water utility company
evaluat-ing the feasibility of a new project to expand the
existing infrastructures in mountain areas may
need information about geomorphologic
forma-tions and associated potential landslide risk from
the local and federal government databases
Agencies in various levels of government rarely
coordinate the development of their applications
Consequently there is often redundancies and
duplications of data even within organizations
belonging to the same jurisdiction (Nyerges,
1989) Users often have to deal with proprietary
systems that require the understanding of the
systems’ native command language, input data
format, and output presentations The problem
is further compounded when there is a need for
communicating with more than one modeling
paradigms or when spatial analysis and
model-ing techniques are used in application areas for
which they were not necessarily designed In most
cases, users’ access, inference, and analytical
ability of spatial dataset and services are limited
by proprietary standards, platform dependence,
and incompatibility
In an e-government environment, simple
trans-actions can require intertrans-actions among multiple
resources possibly from different entities within
the government, and meaningful understanding
of system architectures and the service
compo-sitions Interagency transactions become simple
if the agencies involved in a transaction have homogeneous representation structures as well as the same discourse domain (Malucelli, Palzer, & Oliveira, 2006) A geospatial application can use business services with relative ease if it can un-derstand another application’s service descriptions and representations of workflows and information flows within and across organizations However, these representations become complicated when one needs to embed complex data structures and models into an application For instance, suppose
we are interested in a mobile commerce tion that would provide geospatial information as
applica-a prelude to completing applica-a business trapplica-ansapplica-action The transaction protocol for such an application would require access to and representation of geographic data and models These models themselves may require chaining of multiple services that depend
on service level description of geo-processing models, spatial geometries, spatial analysis, and implementation logic Typical query such as “Find the nearest Italian restaurant along the highway” could possibly be answered by chaining multiple services such as geocoding points of interest, integrating transport networks, creating dynamic segmentation of network, providing routing net-work, rendering cartographic information, and possibly converting text to voice It is possible
to envision integration and chaining of services
to provide higher levels of functionality if such services are distributed all over the enterprise and are accessible in a uniform standard manner (Peng & Tsou, 2003)
Methodological artifacts, techniques for rect description, and interpretation of resources, collectively known as the semantic layer (Vetere
cor-& Lenzerini, 2005), are pre-requisites to high level interoperability in a service-oriented envi-ronment High level or semantic interoperability
is of vital importance if collaborative business processes are involved (Padmanabhuni, 2004)
A complex collaborative process is often needed
to compose complex services like dynamic sualization and query processing of geo-spatial
Trang 23vi-data in real time The representation of semantic
content of space and spatial knowledge has a
special significance in information exchange and
integration As representation of spatial features
are scale dependent, multiple representations of
spatial objects require contextual information of
the spatial reference domain that allows spatial
features to be integrated into application models
Therefore, typical business transactions involving
spatial data interoperability require processes
beyond the data translation or the conversion of
geometric primitives In collaborative business
processes involving multi-agent interactions, the
semantics of the complex spatial application
mod-els needs to be shared to infer or draw conclusions
from such annotations However, understanding
the collaborative aspects of multi-agent
interac-tion to solve complex spatial problems is still in
its infancy (Sikder & Gangapadhayay, 2002)
This article proposes a framework for a
se-mantic-level communication between geo-spatial
services in business processes and application
models The article presents an overview of
interoperability efforts with specific reference
to geo-spatial databases and application models
and reviews the feasibility of an ontology-based
spatial resource integration to combine the core
spatial reasoning with domain-specific application
models Existing industry standards and practices
in geo-spatial interoperability are identified
This is followed by a discussion of the role of
ontology in explicating the implicit semantics
of spatial data models and the need for
formal-ism in descriptions of spatial categories Use of
markup languages for spatial resource description
and the tagging of spatial ontology are
illus-trated Finally, a multi-agent based architecture
(OSIRIS-Ontology-Based Spatial Information
and Resource Integration Services) for semantic
interoperability of spatial data sets and models
is proposed The architecture is illustrated using
an application model that uses domain ontology
of urban environmental hydrology
g Is ser vIces In the
f r AMework of e-g overn Ment
As stated earlier, government agencies within the same jurisdiction rarely coordinate their ap-plication development as well as standardization
in data representation Making data available electronically then becomes a problem whether the potential user of the data is a government agency or otherwise A major initiative in the USA seeks to address this problem The National Spatial Data Infrastructure (NSDI) seeks to build
an organizational and virtual network to promote the sharing of spatial data among federal, state, regional, and local government agencies and the private sector The Federal Geographic Data Committee (FGDC) (FGDC, 2006) is tasked to develop a spatial data and metadata standard as well as to create data clearinghouse FGDC is also responsible for coordinating the development
of a “framework” data (Wayne, 2005) Similar initiatives have been taken by European commu-nities for developing a spatial data infrastructure (SDI) for e-government (Craglla & Signoretta, 2000) As a part these initiatives to share data and services among public and private agencies
as well as to achieve interoperability, various legal frameworks and standards have been insti-tuted The E-government Act of 20021 requires federal agencies to coordinate the development
of standard protocols for sharing geographic information to reduce redundant data collection and promote collaboration and the use of stan-dards (GAO, 2003) As a result, the role of NSDI and SDI is evolving from a simple data access facilitator to integrated service provider where complex geospatial services and functionalities can be chained in a distributed environment to meet user needs The framework of SDI and the role of e-government are viewed as a portal that can be used to access e-government services The geospatial one-stop portal, implementing the NSDI framework, seeks to coordinate and align geospatial data collection and maintenance across
Trang 24all levels of government This portal envisions a
virtual repository of spatial data and Web services
and can provide support to local, state, and federal
programs as well as decision making at various
level of e-government operation The portal can
be used by users to access the following services
(Cummens, 2003):
1 Searching the geospatial one-stop network
for image and feature Web services;
2 Registering for notification when new or
updated data, maps, activities, and
refer-ences are added to system repositories;
3 Viewing metadata to determine if a product
is suitable for the intended use; and
4 Publishing (registering) map services,
im-ages, geographic data sets, geoservices,
spatial solutions, geographic, and land
reference materials
The geospatial one-stop portal can to be
ap-plied in the real world environment For example,
in a real estate business, the portal can perform
the task of a ‘broker’ to discover and chain land
information or cadastre services from various
nodes according to the specifications set by
ser-vice requesters (Radwan, Bishir, Emara, Saleh,
& Sabrah, 2005)
The application of Web services in
geospa-tial service management offers an opportunity
towards the local autonomy of databases Web
services can be used to dynamically query various
GIS layers while maintaining local agency level
independence in a distributed environment From
an organizational point of view, this may be very
appealing Local governments, such as counties
can independently collect and manage data and
still integrate information and services using
Web services A client of the local government
entity, for example, a transportation company,
can directly access the government’s base map
without maintaining its own dataset With
ap-propriate permissions, a client can also update
the government’s dataset from the client’s own
record An extended collaboration and partnership between multiple agencies and clients using Web services can provide opportunity to interoperate through open interfaces and communication protocols Typical geo-processing services may include data management tools like projection and transformation, topology manipulation, indexing, and spatial join
The interoperability issue in the context of e-government services is not limited to technical issues such as linking computer networks There
is a fundamental requirement to share and re-use knowledge networks and reorganize adminis-trative processes to better support the services themselves The key areas of interoperability
in need of consideration when implementing government services include the organizational, semantic, and technical issues (CEC, 2003, 2006)
e-At the semantic level, there is an imperative that the meaning of the information exchanged is not lost in the process of acquiring e-government services from all levels of government Thus, semantic interoperability entails seamless integra-tion of information and services from agencies at different levels whether they are local, regional,
or national This ensures organizational or local autonomy as well as global integration
However, there is growing skepticism whether the vision of geospatial one-stop’s objectives will
be fulfilled (GAO, 2003) and interoperability can be achieved The main obstacles are lack of standards and the requirement of a huge metadata While existing FGDC metadata provides content standards, they lack a framework for semantic annotation of the geospatial content and services The geospatial one-stop portal requires a semantic layer that would contain domain level specifica-tion of knowledge, mediator, and mapping agents
to coordinate among mapping components The semantic layer should be able to decompose users’ declarative requests, compose complex spatial services within the context of user-defined constraints
Trang 25epIste Mo Logy of
Interoper AbLe Agents
In bus Iness processes
Epistemologically, the intrinsic state of an agent’s
reflection of a business process is partially
char-acterized by the internal schema (e.g., relational
or object relational) of the agent In addition, the
agent also offers manipulation methods that can be
used to interface with other agents through specific
access protocol Such autonomous agents can be
considered as a proxy who works collectively on
behalf of some higher entity having rich schema
or domain knowledge For example, in a B2B
e-commerce system, a cooperative mechanism agent
may negotiate with multiple suppliers, monitor
auctions, and infer tactical business strategies in
a competitive environment Agents may not only
involve in collaborative interactions to achieve a
common goal, they may also identify best partner
through negotiations (He, Jennings, & Leung,
2003) Business applications can then exploit
these agent benefits Specifically, a large complex
problem can be decomposed into subtasks that can
then be distributed among the agent
communi-ties specializing in solving domain problems
In a multi-agent environment, the internal state
of agent’s reflection needs to be translated to an
export schema to map conceptual correspondence
Therefore, multi-agent communication paradigms
require semantic level agreement Such semantic
interoperability eventually boils down to the
prob-lem of the identification of semantically similar
objects that belong to different components and
the resolution of their semantic differences (Yeap
& Handley, 1990) In this sense, the semantic
interoperability problem is somewhat similar to
the problem of schema integration in traditional
multi-databases
Different levels of business process
conceptu-alization have given rise to many domain specific
heterogeneous systems, which are often very
difficult to interoperate in applications In recent
years, there has been a significant level of
inter-est to study the role of an agent in system level interoperability by offering interface with special-ized systems that require agents to understand the native command language, input data format, and output presentations In such heterogeneous environments, agents require mapping one-to-one objects on a syntactic basis or measuring the semantic equivalence of objects However, when the representation is complex, for example, spatial databases, simple semantic translation is inadequate as it can result in semantic conflicts Three different types of semantic conflicts have been identified in spatial applications (Goh, 1997): confounding conflicts, scaling conflicts, and naming conflicts Confounding conflicts occur when information items have the same meaning but have different realizations Information items representing the same value but with different reference systems lead to scaling conflicts; and naming conflicts are generated when same items have different rules in different systems A typical example of spatial semantic heterogeneity can start with both naming and confounding conflicts For instance, a “river” and a “body of water” have two different realizations with respect to the scale and context of user perceptions A location-based query such as “find the intersections of a river and a highway in Ohio,” would need a semantic translator to identify the spatial object that cor-responds to the concepts referred by “river” and
“highway” The spatial agent needs to be able
to characterize the semantic content of spatial data and model The representation of “river” or
“body of water” depends on the context of the requesting agent Depending on the context, the geometric representations of “river” and “body
of water” could be also different; the resulting intersection of a “river” and a “highway” could
be a point feature in one representation while it could be a polygon feature in another
An agent’s access to data layers of spatial bases is dependent on the semantic interpretation and corresponding topological definition where spatial relationships such as adjacency relation-
Trang 26data-ships can be reflected in a topological model A
topological model of a highway can be a graph
theoretic model characterized by its “from” and
“to” nodes as well as by its left and right polygon
objects An agent can interpret the semantics of
a textual query that includes “longest highway in
Ohio” in many ways since the agent would need
to understand the definition implicit in
topologi-cal containment of part and whole relationship
Examples of interpretation of “in Ohio” may
include or exclude highways that run along the
state border, that are wholly contained within the
state, or those crossing state boundaries Thus,
different interpretations will result in different
access and processing requirements to different
layers and spatial joins There is no standard or
common formal convention for the description and
categorization of semantic content in the query
which can be used for the global interoperability of
spatial agents In addition, the lack of
context-de-pendent data views can lead to monolithic systems
that do not promote interoperability For example,
it will be difficult for a local government or
busi-ness service provider to be able to update its land
records while serving them to other organizations
without transforming geometric and topological
semantics to make them compatible to the client’s
structure A state highway company would have
to maintain and reflect the changes made by local
governments for its own data view to be able to
use that local government’s base map directly At
present, there is no accepted convention, which
can be used to facilitate global interoperability
of spatial objects
o nt o Logy for seMAnt Ic
Interoper AbILIty
The objective of semantic interoperability is to
be able to attach meaning to information entities
or services and thereby draw inferences from the
semantic annotation In spatial semantic
interop-erability, the integration goes beyond the process
of data translation or the conversion of geometric
primitives The semantic interoperability ally boils down to the problem of the identification
eventu-of semantically similar objects that belong to different databases and the resolution of their se-mantic differences (Kashyap & Sheth, 1996) The use of an ontology (Guarino & Giaretta, 1995) as
a framework for defining similarity among objects has the benefit of a formal definition for concepts
in different metadata, a definition that could be used to define axioms for semantic translation between ontologies The term “ontology” has its root in the philosophical literature as the study of being In the domain of information systems and
AI, ontology has a somewhat different connotation
as an “explicit specification of a tion” (Gruber, 1993; Farquhar, Fikes, & Rice, 1996) and provides a more pragmatic definition: Ontologies are explicit specifications of domain conceptualization names and describe the entities that may exist in that domain and relationships among those entities In other words, the tacit and implicit knowledge hidden in a particular domain
conceptualiza-is explicitly conceptualized in ontology (Guarino, 1997) Ontology is considered as a logical theory accounting for the intended meaning of a formal vocabulary while conceptualizations are the formal structures of reality as perceived and or-ganized by an agent In spatial ontology, although agents may have a shared vocabulary capable of establishing relationships, or mapping between corresponding instances, the conceptualization
of space as “object-based” and “field-based” may
be still implicit among agents
Although spatial ontology is an established concept, and is capable of providing a naturalistic representation of spatial objects, in the sense of
“naive geography” (Egenhofer & Mark, 1995), it
is still a complex specification to be realized tial semantic interoperability goes beyond simple data translation or the conversion of geometric primitives based on a-priori ontology Classical ontology, offering limited expression of spatial relations to simulate spatial processes, can be used to express spatially complex phenomena,
Spa-is not well understood Specifically, such