Maya Secrets of the Pros Second Edition phần 10 ppt

Editing the Subdivision Model Subdivision modeling is just like polygonal modeling, except that the model has levels thatcan be traversed and the menus are slightly different.. Also, jus

Figure 9.52: Placing and scal- ing the sphere

Figure 9.53: dividing the model for testing

Sub-Creating Subdivision Surfaces

Before you convert the polygonal cage to subdivision surfaces, it is important to delete allconstruction history Subdivision modeling can sometimes get slow Additional history that isunnecessary will make it much worse

Once the polygon cage is completed to the point where you decide to apply the vision surfaces, you can finally merge the two sides of the face With both sides selected,

subdi-choose Polygons → Combine to combine the two halves into one continuous mesh (see

Fig-ure 9.54)

Select the adjacent rows of vertices along the center, making absolutely sure that noother vertices are selected except those that run up the exact center of the model (see Fig-ure 9.55) If some stray vertices creep into the selection set, repeat this step until the selectionset is correct

Use the Merge Vertices command to seal the center line between the two halves of themodel If some errant vertices merge together during this operation, the operation acciden-tally closes one or more polygons in the model It is important that this not happen duringthis step, so carefully check the results before proceeding to the next step Any accidentalproblem at this stage will cause many more later

In our example, we chose Edit Polygons → Merge Vertices ❒ and set Distance to

0.0020 By choosing only the vertices that you want to merge and using a relatively lowthreshold for merging, you can help ensure that these common mistakes do not happen Ofcourse, there is always the tried-and-true method of saving often as an insurance policy

Figure 9.54:

Combining the

two halves of

the head

Once the two halves are combined, it is easy to see how the initial planning stages ofthe modeling procedure have paid off (see Figure 9.56) You can visualize the discussion

about edge loops and areas of animation by looking at the wireframe The original edge

loops that were laid out before modeling started can be seen clearly

Figure 9.55: Selecting the center row of vertices

Figure 9.56: (left) The merged polygonal wireframe; (right) the merged model with edge loops

We can now subdivide We wait to do so until the last possible moment because the

subdivided model is slow to work on and time-consuming to update Choose Modify→

Convert → Polygons to Subdiv to convert the model to subdivision surfaces (see Figure 9.57).

Here’s another, more important reason that the subdivision step is not taken until the lastminute: at this stage of the modeling process, asymmetric details are added to the model.Wrinkles and character lines are usually not exactly symmetrical When these details areadded, the model needs to be in a state where it is no longer creating perfectly symmetri-cal details across its two halves You add these details using the subdivision modeling lay-ers and modeling options

Editing the Subdivision Model

Subdivision modeling is just like polygonal modeling, except that the model has levels thatcan be traversed and the menus are slightly different Also, just like polygonal modeling,only a limited set of tools is necessary to create a great subdivision model The rest of themodeling tools are great to use, and you should learn how to use them But only a handful ofthe subdivision modeling tools in Maya were used to create this model

Figure 9.57: The

converted model

Most of the subdivision modeling that was done on this model was surface editing

using the options in the pop-up menus and choosing Subdiv Surfaces → Partial Crease

Edge/Vertex.

Surface Editing

When modeling in Maya subdivisions, the marking menu (which appears when right-clicking

the model) changes (see Figure 9.58) The new options let you edit the model at different

lev-els using different entity types With a knowledge of polygonal modeling, and an

understand-ing of how subdivision levels work, you can begin to create models with subtle details very

quickly

If you want to add detail at the base level, or the subdivision zero level, choose the

Coarser option on the marking menu You can then select vertices, faces, or edges to edit To

work at a finer level or at subdivision level 1 or above, choose the Finer option.

The distinction between levels going from coarsest (level zero) to finest (the highestlevel of subdivision that a modeler would care to set) is how subdivision modeling differs a

great deal from polygon modeling

Notice in Figure 9.59 how the vertices do not display as simple points as they would inpolygon modeling mode; they display as the numeral 0 Using a coarser setting allows us to

Figure 9.58: The subdivision marking menu

affect large areas quickly Editing in this mode lets the modeler make progress quickly onlarge areas.

Similarly, the vertices at level 1 display as the numeral 1 Using a setting like thisaccommodates the creation of small details The finer the selection, the tighter the details.Editing the surface using a level 1 or finer setting means that we are not making big changes

to the model; we’re creating small details (see Figure 9.60)

You can edit the edges along a surface in the same way you edit in polygonal modelingmode The display between coarser and finer levels is an obvious increase in detail that is notdesignated by visible numerals (see Figure 9.61)

You can see the results of subdivision surface editing in Figure 9.62 The edited figurehas many asymmetrical details and many small wrinkles that the unedited version does not.All these small details increase the realism and make lighting and texturing easier, withoutdramatically increasing the computational requirements of the model Each subdivisiondetail is added to a localized region The rest of the model that is not detailed is not affected

by the additional small elements created using this technique To see the 3D version of theunedited model, open subD_modeling21.mbon the CD To see the 3D version of the editedmodel, open subD_modeling22.mbon the CD

Figure 9.59:

Ver-tices at level zero

Figure 9.60: tices at level 1

Ver-Figure 9.61: Edges at (left) level 0 and (right) level 1

Using the Partial Crease Command

Choose Subdiv Surfaces → Partial Crease Edge/Vertex to create sharp, angular areas along

selected edges and vertices within the smooth subdivision model If the model needs detailsthat would normally be created by adding geometry, this command adds the detail withoutadding geometry

Usually it will not be necessary to go any finer than level 0 to use this command to ate creases along the skin of the model The edges along the lines that require detail areselected first Figure 9.63 shows the edge of the eyelid highlighted, ready to use the PartialCrease Edge/Vertex command

cre-The line that was smoothed out now shows a crease where the selected edges were.This line will catch a dramatic highlight when rendered and will create a realistic appearance(see Figure 9.64)

Another area that requires a crease is the line that extends from the side of the nose tothe corner of the mouth

This character line usually animates quite a bit and is not an area where excessive detailshould be added The more complex the geometry in areas like this, the more likely it isthat the blend shapes and facial animation rigs will have problems

Using the Partial Crease Edge/Vertex command is a perfect choice for creating thisdetail As in the example shown in Figure 9.64, the edges along the area are selected beforethe command is executed (see Figure 9.65)

When the command is executed, the line along the face is perfectly tightened Usingconventional polygon modeling methods would make this process difficult and complicated.The Partial Crease Edge/Vertex command simplifies the modeling in these areas a great deal(see Figure 9.66)

Figure 9.62: (left) An unedited subdivision model and (right) an edited version

Figure 9.63: The eyelid line selected for the Partial Crease Edge/Vertex command

Figure 9.64: The eyelid highlight line

And our final model shows the results of our detailed work (see Figure 9.67) If youwant to see the model in 3D, open subD_modeling_final_details12.mbin the CD.

The problem is, digital art is like a moving train To remain on track, we have to stay

in front of it These techniques are great, but something else may come along that will make

these techniques obsolete

In the end, you—the modeler, the artist—must be the one who makes the model great

You create the subtle form of the details of the face, the overall shape of the head and neck,

and the little surface tweaks that bring the flesh to life The tools in Maya are only the

pen-cils and paintbrushes in your tool box; they cannot make the model great by themselves

If you use the tools explained here, you will be able to develop more imaginative tions than those you developed using the tools that you have been using before The flexibil-

crea-ity and speed of polygon-to-subdivision modeling can help you make your creative visions

truly come to life

Figure 9.67: The final model

2-node camera (Camera and Aim), 59

for camera shake, 68

dolly-and-pan shot with, 60–62

3D models

2-dimensional artwork for, 230, 231

hand-drawn texture integration with, 37–48

3-node camera (Camera, Aim and Up), 60

16:9 aspect ratio, 66

A

accessibility shaders, 95

Aim node, 59

pan with TranslateX, 72–74

tilt with TranslateY, 74–76

→Motion Paths →Attach to Motion Path, 167

→Skeleton→IK Spline Handle Tool ❒, 181

animation

areas in character model, 232

control for offset and speed, 146–147

animationCurve nodes, names for, 132

antenna See car antenna

arcExp.txt file, 223–225art directors, 114aspect ratio of 16:9, 66assembly pipeline, 127–128

attachLocators.mel script, 8

Attribute EditorCamera Attributes section for focal length, 63changing background color, 47

with custom attributes, 219

to delete antenna collisions with car, 186

for hair ConstraintShape node, 154

IK Solver Attributes, Advanced Twist Controls, 168Primary Visibility, 103

attributes See also specific names of attributes

expressions to create new, 190automatic mapping, 38

B

Being There, 63

Bend Rate, of cloth, 15

Bend Resistance, of cloth, 15, 15 binding cloth garments together, Cloth constraint for, 21, 22

blend attribute, 145Blend Colors shader node, 45blocking, keyframes for, 75

bone edge loops, 234, 234

boom, 58boom shot, 58bounciness of cord, 176

box, as collision object, 14

bracelet garment, 27–30 animation, 30–33

constraining beads, 32–33deforming, 31–32observing motion, 30–31simulating and relaxing, 29–30

268

Index

Note to the reader: Throughout this index boldfaced page numbers indicate primary discussions of a topic Italicized

page numbers indicate illustrations

truncating, 14

Camera, Aim and Up (three-node camera), 60

Camera and Aim (two-node camera), 59

for camera shake, 68

dolly-and-pan shot with, 60–62 camera movement, 57–83

abrupt start and stop, 62

advanced, 67–77 handheld camera, 71–77 shake, 67–71

capturing with Maya Live, 77–82, 78

car suspension with hair dynamics, 190–193

CD in book, continued

buildFieldConstraint.mb, 22buildMeshConstraint.mb, 21buildTransformConstraint.mb, 20camShake_end.mb, 71

camShake_start.mb, 67car_model.ma, 183car_soft bodies_finished.ma, 182car_soft bodies_setup.ma, 181clothModel.mb, 3

dollyPan_start.mb, 61dollyZoom_start.mb, 65dupeball MEL script, 147garmentSettle.mov, 12Hair_Walk_Start.mb, 162handHeld_end.mb, 77handHeld_mid.mb, 74handHeldPan001, 78handHeld_start.mb, 72hicon_shperical.hdr, 111katana.mb, 110lightDome.mb, 98matchMove_handheld.mov, 82matchMove_tracked.mb, 82noiseyArc.ma, 226noiseyArc.mov, 226noisyFountain.ma, 213noisyFountain.mov, 213noisyGate.ma, 217noisyGate.mov, 217Octopus_finished.mb, 158Octopus_start.mb, 155rain_puddle_soft_body_start.ma, 195ring_dust.ma, 206

Rope_Finished.mb, 158SecurityShip.mb, 104Shark_start.mb, 167skirt_Attach.mb, 12skirt_curves.mb, 5skirt_garmentBuilt.mb, 7skirt_jump.mb, 13skirt_jump.mov, 17smattrDwn.mel script, 148smattrUp.mel script, 148subD_modeling01.mb, 235subD_modeling03.mb, 238subD_modeling06.mb, 244subD_modeling14.mb, 255subD_modeling21.mb, 262subD_modeling22.mb, 262TurboProp_TXTR.mb, 115UVGlue.mel, 32

Channel box pop-up menu, adding scripts to, 149

defining character for, 137–141

expressions and utility nodes in rigs, 144–149

spaces and underscores in names, 131–133

golden rules of successful, 133–137

manual update, 24–25 saving work, 26

settled after simulation, 3

setup for general animation, 12–17 animating skirt, 13–14

cpProperty attribute update, 15–16cpSolver attribute update, 15–16gravity constraint, 16–17

meshing constraining cloth to model, 13 saving relaxed garment state, 12–13 truncating cache, 14

tutorial on skirt making, 3–12 cpProperty attribute, 11–12 cpSolver attribute, 9–10

Cloth menu

→Create Collision Object, 9, 14, 17

→Create Garment, 6

→Create Seam, 6

Cloth Panel icon, 6

cloth solver, disabling, 30clothModel.mb file, 3

clumping, from rand function, 210, 210

clumpyness of particles, 216collapsing polygons, 248

Collateral, 71

collision constraint, for cloth motion, 23

collision environment, for cloth, 29

collision object, 9

for antenna, 186

attributes, 9 box as, 14

converting surface to, 17

to create dust, 204–205for dancing MP3 player, 176–177

self-intersection in, 24, 24

sphere and particles, 196Color Balance menu →Color Gain, 112

Color Chooser, 117

for hair, 154Constraints menu →Mesh, 13

copy and paste keyframes, 70

current position curves, 152, 153

curve control, creating and attaching to DAG node, 134

Curves menu, →Pre Infinity, →Cycle, 168

curves to create panels

instancing to manage, 5rules, 2

cylindrical mapping, 38, 38

D

DAG (Directed Acyclic Graph) node, creating curve trol and attaching to, 134

con-Damp attribute, for car suspension, 193

Dances with Wolves, 58

dancing MP3 player, 171, 171–177, 177

collisions, 176–177creating cord, 172–174dynamic curves and animation, 174–176daylight scenes, HDRI for, 87

Debevec, Paul, 89deformable objects, 179deformers

amount of bend for antenna object, 189–190

hair curves as, 155–158

delay in camera movements, 68deleting

connection in Hypershade, 46hair systems, 194

→Current Position, 156

→NURBS Components →Normals, 18

→Polygon Components →Normals, 18

→Show→Show Last Hidden, 164dolly a camera, 58

dolly-and-pan shot with two-node camera, 60–62 dolly zoom, creating, 65–66

dollyPan_start.mb file, 61dollyZoom_start.mb file, 65double linears, 144dpi (dots per inch) for printout, 43Drag attribute, for car suspension, 193

Dragon Ball Z, 37

droid, ambient occlusion for, 96–101, 97, 98, 99

compositing passes, 101–102, 102

dupeball MEL script file, 147

duplicate names, difficulties from, 129, 129 Duplicate Options dialog box, 130, 130

dust, rolling ring to kick up, 201–207, 203, 207

collision detection, 204–205Dutch angle, 59

dynamic NURBS curves, for hair, 151dynamic particles, assigning surface points to, 180–181

→Create Active Rigid Body, 195, 202

→Create Passive Rigid Body, 202

→Create Soft Body ❒, 195

→Move Keys Tool, 76

→Scale Keys Tool, 76

Edit NURBS menu →Reverse Surface →Direction, 18

Edit Polygons menu

→Sculpt Polygons Tool, 239, 247, 247–248

→Selection→Select Contiguous Edges, 244, 245

→Split Polygon Tool, 239, 244, 251, 256

Emitter Options dialog box, 199

energy vortex, 214–217

Environment Ball, to map reflections, 90

Environment Textures menu, →Env Ball, 90

in rigs, 144–149

extrudingpolygons, 248–250for rope thickness, 160rows of polygons, 244–246

eye area of character, 256, 256, 257

F

fat edge loops, 234, 234

field constraint, for cloth motion, 22–23

field of view (FOV), focal length of lens and, 63Fields menu

→Gravity, 212

→Radial❒, 214

Fifty Percent Grey, 86

file format, floating-point, 86, 118, 120

car suspension with hair dynamics, 190–193 raining cats and dogs, 194–201

particles as rain, 198–199splashes, 200–201springs for ripples, 196–198

rolling ring to kick up dust, 201–207, 203, 207

collision detection, 204–205floating-point file format

flexibility from, 120

for HDR images, 86, 118