LightWave 3D 8 Texturing phần 8 pptx

Making an Atlas UV MapTo make an Atlas UV map, select the model that you wish to unwrap, click on New UV Map on the Map tab in Modeler, and select Atlas.. Rotate your Perspective viewpor

These distortions are caused by the subdivision of the model and not actually be perfectly fixed, since they are an artifact of LightWave’ssubdivision algorithm So don’t worry about them too much.

can-13 If we zoom out of the model now and take a look at the entire thing, itbecomes obvious that the whole map is a little too stretched along they-axis In the UV map, this is the v-axis, and we need to scale the mapdown along this axis to fix this

However, because of the nature of discontinuous UV maps in Wave, we need to unweld the points in the model before scaling them;otherwise parts of the model are going to remain stuck in place

Light-14 Press Ctrl+u to unweld all your points The model will look a bit odd inyour viewport if you were displaying your model in Subpatch mode(Tab), so generally I just press Tab again to go to normal Polygon displaymode

15 Now go to your UV viewport, select all the polygons, and press the “h”key to activate the Stretch tool Holding down the Ctrl key (to constrain

the stretching to a single axis), squash the polygons downward to squash

them along the v-axis Squash the polygons until the squares in the ture begin to look more square instead of rectangular

tex-Figure 15-35

16 Press the “m” key to merge your points again before continuing.

Of course this squashing altered some of the editing we did previously,

but you don’t really need to worry all that much about it, because the

squashing now on the neck is relatively minimal and is not likely to cause

problems when you paint a texture for it later on

17 Let’s now focus on the top of the head Rotate your Perspective viewport

so that the top of the head is visible You’ll see some nasty pinching at

the pole where the cylindrical map comes to a point

Figure 15-36

Figure 15-37

To be honest, there is no real point in spending much time actually ing this to fix it because you’ll more than likely cover this area with hair,using Saslite or Sasquatch, or even modeled hair If you want the character

edit-to be bald, it would be better edit-to create an additional planar projection alongthe y-axis (just a standard projection, no UV map necessary) of the top ofthe head, and blend the two textures together using an alpha channel orFalloff settings in the Texture Editor

So this pretty much concludes the process of editing the UV map for ahead Some people like to create additional projections for the ears as well,but that isn’t always entirely necessary, as ears generally don’t tend to havemuch texture detail on them It’s up to you, and since you now have thismodel, you’re free to do with it as you please

Atlas UV Maps

Using Atlas Maps

Aaaah, the ever-tempting Atlas unwrap option This often looks extremelyalluring to use since it gives the impression of being an ideal option for any-thing Let me quickly banish that idea Although the idea of an atlas unwrapseems like a great one, more often than not the result is a disjointed mess,especially when unwrapping organic models In my experience, this option

is not really suitable for characters (or any organic objects, for that matter)unless you want to spend a really, really, really long time editing the map.The following image demonstrates the fragmented chaos that resultsfrom unwrapping a simple head object

Figure 15-38

Figure 15-39 shows the same map after about an hour of editing, and it

still needs a lot more editing before it can be of any use

The fragmentation that occurs from unwrapping using the Atlas unwrap

option makes it disastrous for anything other than structures such as

build-ings, cars, or anything else that has mostly retained simple shapes

(primitive shapes)

The atlas unwrap does have one main advantage: It can be used to

unwrap an entire object, regardless of the orientation of any part of that

object This is because atlas does not use an axis to unwrap; it simply

flat-tens out the entire object along an arbitrary axis Pretty cool!

So basically, you do not have to worry about choosing the right axis

along which to unwrap, depending on what sort of alignment the different

parts of the model have Instead, it is simply a matter of clicking to unwrap,

and then dealing with the resulting map as it turns out

In the case of atlas mapping, editing is essentially the key to success, as

the result of the initial unwrap is so very unusual Atlas maps are always

very fragmented, no matter what settings you use Of course, as we know,

editing is essential in all unwrapping methods, but in this case it takes on

more importance since the initial unwrap is, in almost every case, totally

unusable without extensive editing This only really excludes extremely

simple buildings, which, although they can definitely be improved by editing,

can use the initial map obtained in many circumstances

When editing atlas unwraps, one tends to use tools such as Flip UV

Point Map a lot, since many polys often become flipped when using this

method We explore all the UV editing tools in great depth in Chapter 16

Figure 15-39

Making an Atlas UV Map

To make an Atlas UV map, select the model that you wish to unwrap, click

on New UV Map on the Map tab in Modeler, and select Atlas

You’ll notice that the Atlas UVmapping type has a different setup

of options compared to the Planar,Cylindrical, and Spherical types

The Relative Gap Size optiondefines the distance between thefragmented sections of the map

Larger values will cause the tions to be farther apart from oneanother in the map, but rememberthat since the entire map needs tofit into the square UV template that is a finite size, increasing this value alsomeans that each part will be smaller in the UV map If you want to paintreally fine details into your textures, you are going to have to create muchlarger images for your textures since each part is so small within that map.The following image shows an unwrapped cube with a Relative GapSize value of 20% (on the left) and one with a value of 80% (on the right) Ihave drawn over the map with bolder lines to make the details clearer

sec-The Segment by Surface and Segment by Part options allow you to specifywhether the discontinuities in the UV map will be positioned according todifferent surfaces or parts assigned to the model that you are unwrapping.For more information on discontinuous UVs, refer to Chapter 16

So if you have, for example, three different surfaces assigned to themodel, you can choose to have the fragmentation defined by these different

Figure 15-40

Figure 15-41

Atlas UV Map Tutorial: Unwrapping a Small

Building

This tutorial demonstrates the use of Atlas UV mapping to unwrap a small

building We will unwrap the outer walls first, and then do the inner walls

1 Open the 4.2.4-small_house.lwo object from the companion CD-ROM in

Modeler

2 The roof and the walls are on two separate layers Let’s go to the wall

layer and concentrate on that one first Select all the outer walls of the

house I have already assigned a separate surface to them for ease of

selecting, so all you have to do is open the Polygon Statistics panel (hit

“w”) when in Polygon mode (Ctrl+h), go down to where it says Surf, and

select the Walls Outer surface Click on the little + symbol to select the

polygons to which this surface is applied

Figure 15-42

3 Go to the Map tab and click on

New UV Map Select Atlas as theMap Type and give it the name

“outer walls.” Leave the othervalues as they are and click OK

4 Change one of your viewports to

UV Texture, and the map shouldautomatically be displayed in theviewport As you can see, all thewalls are nicely flat in the UVtemplate

5 Open the Image Editor and

load the _uv_checker.jpgimage from the companionCD-ROM

6 Open the Surface Editor, go

to the Walls Outer surface,and open the Color TextureEditor Change the defaultlayer Projection to UV,select the “outer walls” UVmap from the UV Map list,

Figure 15-43

Figure 15-44

Make sure that your Perspective viewport is set to display textures, and

you’ll see the checkerboard image applied to the model The outer walls, as

you can see in Figure 15-47, are almost perfect

If we look at the area immediately to the right of the doorway, we can

see that the checkerboard image is slightly squashed in this area

Figure 15-46

Figure 15-47

7 These polygons are slightly too wide in the UV map so we need to usethe Stretch tool to fix this You will have to unweld the vertices beforedoing this though, as this area is discontinuous, so press Ctrl+u tounweld the points before using the Stretch tool.

8 Now select the polygons that we need to squash, go to the UV viewport,select the Stretch tool (“h”) and squash the polygons inward along theu-axis (horizontally) until the patterns become square instead of rectan-gular, as shown in Figure 15-49

Figure 15-48

Figure 15-49

Leave all the points in the UV map unwelded for now.

At the moment, the walls in the map are not positioned alongside their

correct counterparts In other words, the walls in the UV map are not

nec-essarily flanked by the walls that are actually next to them in the model So

ideally we need to arrange them correctly in the UV map to make the

tex-ture painting simpler, since there will be fewer seams to deal with

9 Let’s start with the door area and the piece of wall to its left Select the

polygons in this area You’ll notice that in the UV map, these two parts of

the wall do happen to lie alongside one another In Figure 15-50 I have

made the selection in the UV map bolder so that you can see more

clearly what you need to be doing

10 Move these out of the actual UV area so that we can start arranging

things correctly Move them up and position them above the actual UV

map When you select the polygons to move them, do so in Point mode

(Ctrl+g) instead of Polygon mode Moving the polygons around in

Poly-gon mode sometimes leaves points behind

Figure 15-50

11 Now let’s move clockwise around the house and move the walls in the

UV map into place Rotate your Perspective viewport around so that youcan see the walls to the left of the section we just moved Select them inyour viewport so that you can see where they are in the UV map Wewant to have these positioned directly to the left in the UV map as well,

so select the points of this section in your UV viewport, and move them

up and to the left of the area we moved previously

Figure 15-51

Figure 15-52

Rotate your Perspective viewport now so that you can see the back of

the house

You’ll notice something a bit odd In your Perspective viewport, select

these polygons from left to right and watch how they are selected in the UV

viewport at the same time Notice something a bit odd? Yes, they are

backward!

12 No need to panic — this is a common occurrence in Atlas UV maps All

we need to do is use the Flip

UV command to fix it Select

all the points of that section of

wall and click on the Flip UVs

button Select Flip U and click

OK

This flips the points horizontally, so that they now flow correctly

13 Select the points for this section and move them into place on our row of

walls Move them up to join with the new row of walls we are building at

the top of the UV map

14 Swivel your Perspective viewport around to the side of the house now,

and select the walls there Move them into position on the new row at

the top as well, and repeat this process for the next section as well

15 Last, we have the little piece that we squashed earlier If you select

these polygons from left to right in the Perspective viewport while

look-ing at the UV viewport, you’ll notice that these polygons are also flipped

incorrectly Once again, simply select the points of this section, hit the

Flip UVs button, and select Flip U Then, move this section into place on

the row of walls

Figure 15-53

Figure 15-54

16 Now select all the points in this long row of walls, scale them down, andposition them back into the actual square template of the UV map.

17 Because they are so small in the UV map now, you will need to create avery large texture map to get detail into these small areas Since we stillhave so much room going to waste in the UV map, select the points ofthe polygons forming the front and left facades of the house and movethem below the other row You’ll ideally need to rearrange the sectionsforming the front part a little, so that the part that is to the right of thedoor part is now to its right in the UV map (previously it was on theother end of the row from that section)

18 Scale these sections up as much as you can in your UV map now, and itshould look like Figure 15-55

19 Okay, so let’s move onto the

inner walls of the house Selectthem by surface from the Poly-gon Statistics panel (“w”), andclick on New UV Map SelectAtlas and call the map “innerwalls.” Leave the other settings

as they are

Figure 15-55

Figure 15-56

20 You’ll get a nice big fragmented map looking like Figure 15-57.

You are probably freaking out right now, but relax because I have some

good news for you Remember when we unwelded the points earlier? Well,

because the entire model was unwelded, LightWave has assumed that all

the pieces are separate, and so it has not kept them intact when it

unwrapped the model

21 So press Ctrl+z to kill the UV map

22 Merge all the points in the model again by pressing “m.” Now create the

UV map again, using the same settings I described in step 19 Ahh, that’s

much better

Figure 15-57

Figure 15-58

Don’t worry about all the criss-crossing lines everywhere; they are onlythere because pieces of wall that should be alongside each other currentlyare not Once we have edited the map, those lines will no longer be there.

23 Go to the Surface Editor,

select the Walls Inner face, and load the

sur-_uv_checker.jpg image intothe Color Texture Editor,using the “inner walls” UVmap

24 Now we need to unweld

again because we don’t want

to be bothered with nuities while editing Sopress Ctrl+u to unweld allthe points

disconti-25 Now simply do the same as

we did with the outer walls,

by selecting each section,moving it up to the top, andarranging a nice long row of wall sections Watch out for flipped poly-gons, as a few of the sections in this map are flipped the wrong way onthe u-axis in the UV map

Figure 15-60 shows the long row I made, starting from the left side ofthe back inner wall on the left end of the row

Figure 15-59

Figure 15-60

26 Once you have them all in a row, split the row into two again, and

arrange them so that they will fit into the UV map space

27 Okay, now we are left with a bunch of polygons that form all the

horizon-tal parts of the model First, we can get rid of the top row that runs along

the top of the walls, because the building has a roof and we will therefore

never see those polygons Select them in your Perspective viewport, and

then click on Clear Map This will remove them from your UV map

They will leave some points behind in the UV map — select those points

and click on Clear Map again to delete them from the map

Figure 15-61

Figure 15-62

28 Now we are left with the window ledges, the inner doorframe, and amess of weird distorted polygons Let’s deal with the weird ones first.Select them in your UV viewport.

You’ll notice that they are actually polygons on the outside walls, so wedon’t need them here either Click on Clear Map again while they areselected Select any points that they leave behind and clear those as well

29 All that we have left now are the doorframe polygons and window

ledges You are really free to arrange these to your own personal ence Personally, I really couldn’t be all that bothered about them, so Ijust arrange them all along the bottom of the UV map If you really want

prefer-to, you can arrange them inside the window holes in the appropriate tions in the parts you’ve been editing Now arrange everything snugglyinto the UV space

sec-Figure 15-63

And that’s atlas UV mapping A lot of moving things around and

rear-ranging, but useful for situations like this

30 Merge your points by pressing “m.” And that’s it!

Figure 15-64

Map Transformation and Editing Tools

UV Map Editing Tools

Of course, creating UV maps is not just about unwrapping the model andtaking it into Photoshop (or whatever paint package you are using) Themajority of the time that you spend on UV maps is spent on editing the darnthings so that they are actually usable Once we have made a new UV map,

we look to the UV tools in Modeler to start fixing up the stretching andweird distortion that invariably creeps into your unwrapped template.All the tools that we need are found within the menu under the Map tab

in Modeler

Not all of the options we find here are for UV maps, as this tab is for

working with all vertex maps, of which UV maps are only one particular type.

So if you find yourself wondering why I have ignored some of the buttons on

this panel, now you know This chapter only deals with UV mapping tools

General Commands

The first bunch of options we encounter under the Map tab are

basically just the usual Copy and Delete and Rename functions

that we are accustomed to elsewhere in the LightWave

pack-age, as well as a couple of other, perhaps unfamiliar terms You

can click on the Edit Maps and More buttons to access a few

other commands as well

Let’s look at each of them, one by one

Set Map Value

To use this function, you need to select points within your currently active

UV map (the one that is

show-ing in your UV map viewport)

By selecting points and

enter-ing in any U or V value, those

points will be moved to those

coordinates within the UV

map

The first value represents

the U coordinate, while the second value represents the V coordinate

This is great for fine-tuning your UV maps, especially if there is any

fragmentation (such as the fragmentation that occurs in atlas maps) and you

need to place points back together with a high level of precision I use this

tool a lot when editing UV maps

Copy Vertex Map

Click on the Edit Maps button to access

this command This option copies the

currently selected UV map, just as its

name suggests Copying a UV map

cre-ates a new one that you can name as

you wish

You can use this option to create one big UV map from a bunch of

differ-ent maps that you have already made Simply select the maps one by one,

and when the Copy Vertex Map window pops up, simply enter in the name

of the UV map that you wish to copy it to This is useful for when you are

working with models like game models, where you are limited to the

num-ber of images that you can use on a character, so you can unwrap all the

Figure 16-2

Figure 16-3

Figure 16-4

different parts separately and then simply put them all together in a singlemap and arrange them so that you can texture all the different parts in a sin-gle image.

Delete Vertex Map

Click on the Edit Maps button to access this command This option deletesthe currently selected UV map Use this one cautiously as there is no fur-ther prompting to confirm the deletion

Rename Vertex Map

Click on the Edit Maps button to accessthis command Use this option torename the currently selected UV map

A new window pops up for you to enter

in the new name

Clear Map

If you wish to remove certain polygons from within a UV map, use thisoption Simply select the polygons that you wish to remove, and press thisbutton

If no polygons are selected, the entire contents of the UV map areremoved

Be aware that due to the nature of UV maps, removing polygons fromthe map removes the immediately surrounding polygons as well Be sure to

unweld (Ctrl+U) the points in the map before using this if you wish to keep

all the surrounding polygons intact within the map Just don’t forget toremerge the points again afterward by pressing “m.”

Cull Map

Click on the More button to access this command Since I have absolutely

no mathematical abilities whatsoever (I can barely count over 10), I have alittle trouble really fully understanding this tool’s function and usefulnesssince the explanation of it in the LightWave manual left my brain reelingsomewhat

However, after researching it a little, I have a decent explanation of itfor you This tool affects points in a region of your UV map that you specify

by entering in a certain value, which determines the Threshold Magnitudebelow which all points will be

selected or deselected,depending on which option

Figure 16-5

This value is reached by using a calculation to determine the region

that will be affected by the action, namely the addition of the square root of

the U value to the square root of the V value

All that said though, I have never used this option! When I want to

remove points or polygons from a UV map, I generally just select them and

hit Clear It’s more straightforward

Normalize Map

Click on the More button to access this command

This function scales the selected vertex map from the

Source VMap list according to the Minimum and

Max-imum values specified in the respective fields

This is handy for ensuring that the map makes

the most of the UV map space provided I usually just

scale this by hand, as I sometimes want to have

differ-ent areas in a UV map scaled according to how I want

to paint them later on, but this can save you time if it is a simple projection

that you have been editing, and you now want to simply size up to fill the

space with the touch of a single button Just be careful that it does not

dis-tort any areas that shouldn’t be disdis-torted (although this isn’t all that likely to

happen)

Using the UV Mapping Tools

Under the Texture heading on the Map tab, we find the tools

for creating and editing our UV maps for texturing

New UV Map

Obviously, this particular function creates a brand new UV map

for the currently selected polygons or object in Modeler

Clicking on the button

opens a window from which

you select your projection, a

name for your new map, and

a few other options

From the Map Type

drop-down you can select the

type of projection that you

wish to use for your UV map

For more information on

each of these projection

types, take a look at Chapter

14

Figure 16-7

Figure 16-8

Figure 16-9

Once you have selected a type of projection, select the axis that youwish to apply that projection along by clicking on the desired axis button.You can have your UV settings automatically calculated for you, or youcan manually enter your own settings for the placement and scale of the UVmap by clicking on the Manual button next to Settings and entering yourown values Since you can edit your UV map once it is made, changing thesesettings is not always necessary.

it to edit the settings of anexisting UV map by select-ing that particular map fromthe Texture Name list,which lists all UV maps cur-rently assigned to that model

This allows you to change the projection type, axis, scale, and position

of the existing UV map, which can be particularly useful if you created that

UV map without using the Initial Value option in the Create UV TextureMap window

The Make UVs command can also be used to add additional polygons to

an already existing UV map Select the polygons you wish to add to the map,click on Make UVs, and select the map’s name from the Texture Name list.This is a useful way of making a single UV map out of a few maps with-out using the Copy Map command

Generally, it is advisable

Figure 16-10

Figure 16-11

carefully selecting points and flipping them manually and then trying to

carefully reposition them, using this command saves you time and effort

Transform UV

Clicking on the Transform

UV button brings up a panel

from which you can

numeri-cally adjust the Offset, Scale,

and Rotation values around a

specified Center of your

cur-rently active UV map

Remember that UV

values are defined by

per-centage values from within

the UV space, so you would

enter values between 0% and

100% for these options Use the Center value to define the point from which

these values are calculated By default, the Center value is 0% for both U

and V coordinates, which means that all Offset, Scale, and Rotation values

will be calculated from the lower left-hand corner of the UV map outward If

you wish to make these changes from the actual center of the UV map, you

would enter values of 50% for both U and V in the Center fields

I don’t ever use this command, since I have a habitual tendency to do

everything by hand as much as I can when editing my UV maps

Poly Map

As these options are no longer used, they are not discussed here

Point Maps

Looking under the Point Maps drop-down, we find two

com-mands — Spread UVs and Quantize UVs

Spread UVs works with quads (four-sided polygons)

only, and basically allows you to size them by using numeric

values within the UV space

The Quantize UVs command snaps selected points

in the UV map to the grid using the values entered into

the appropriate fields

Figure 16-12

Figure 16-13 Figure 16-14

Figure 16-15

Again, these are options that I never really use In fact, I don’t think Ihave ever used them because of my tendency to eyeball everything andmove points around by hand.

Set UV Value

This command is accessed from the More drop-down The Set UV tool is fornumerically positioning points within the currently active UV map It basi-cally does the same thing as the Set Map Value command we looked atearlier except that this tool is specifically for UV maps, so you have optionsfor entering in values for U and V instead of X, Y, and Z as we have in theSet Map Value command

This tool is particularlyuseful for ensuring that pointsmeet where they are sup-posed to when you’ve beenediting a UV map with thepoints unwelded

Click on either the U or the V button and enter a desired percentagevalue within the UV space onto which you would like to position theselected points This is a very useful tool for precision, especially in thosepesky UV maps where things have become horribly fractured (such as anAtlas UV map)

Polygon Normal UVs

This command is accessedfrom the More drop-down

The command projects thetexture UVs along the poly-gon normals, mapping theimage flat on the normal

It is a tool that works with poly maps, which is the predecessor to thediscontinuous UV maps that we work with now Since we don’t really needpoly maps anymore, this tool (along with the other poly map tools) has reallyoutgrown its usefulness, and I am guessing that the only reason it is still inthe program is for the off chance that you may happen to be given a reallyold LightWave model to work with that uses them Otherwise, you canignore it

UV Spider

This command is accessed from the More drop-down menu When you

Figure 16-16

Figure 16-17