Maya Secrets of the Pros Second Edition phần 10 ppt

■ Modeling the Face 257 Figure 9.52: Placing and scal- ing the sphere Figure 9.53: Sub- dividing the model for testing 4345c09_p3.1.qxd 1/1/05 1:52 PM Page 257 Creating Subdivision Surfaces Before you convert the polygonal cage to subdivision surfaces, it is important to delete all construction history. Subdivision modeling can sometimes get slow. Additional history that is unnecessary will make it much worse. Once the polygon cage is completed to the point where you decide to apply the subdi- vision surfaces, you can finally merge the two sides of the face. With both sides selected, 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 no other 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 selection set is correct. Use the Merge Vertices command to seal the center line between the two halves of the model. 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 during this step, so carefully check the results before proceeding to the next step. Any accidental problem 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 low threshold for merging, you can help ensure that these common mistakes do not happen. Of course, there is always the tried-and-true method of saving often as an insurance policy. 258 chapter 9 ■ Advanced Character Modeling Using Polygons and Subdivision Surfaces Figure 9.54: Combining the two halves of the head 4345c09_p3.1.qxd 1/1/05 1:52 PM Page 258 Once the two halves are combined, it is easy to see how the initial planning stages of the 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. ■ Modeling the Face 259 Figure 9.55: Selecting the center row of vertices Figure 9.56: (left) The merged polygonal wireframe; (right) the merged model with edge loops 4345c09_p3.1.qxd 1/1/05 1:52 PM Page 259 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 last minute: 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 are added, 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 that can 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 the modeling tools are great to use, and you should learn how to use them. But only a handful of the subdivision modeling tools in Maya were used to create this model. 260 chapter 9 ■ Advanced Character Modeling Using Polygons and Subdivision Surfaces Figure 9.57: The converted model 4345c09_p3.1.qxd 1/1/05 1:52 PM Page 260 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 highest level 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 in polygon modeling mode; they display as the numeral 0. Using a coarser setting allows us to ■ Modeling the Face 261 Figure 9.58: The subdivision marking menu 4345c09_p3.1.qxd 1/1/05 1:52 PM Page 261 affect large areas quickly. Editing in this mode lets the modeler make progress quickly on large areas. Similarly, the vertices at level 1 display as the numeral 1. Using a setting like this accommodates 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 modeling mode. The display between coarser and finer levels is an obvious increase in detail that is not designated by visible numerals (see Figure 9.61). You can see the results of subdivision surface editing in Figure 9.62. The edited figure has 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, without dramatically increasing the computational requirements of the model. Each subdivision detail 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 the unedited model, open subD_modeling21.mb on the CD. To see the 3D version of the edited model, open subD_modeling22.mb on the CD. 262 chapter 9 ■ Advanced Character Modeling Using Polygons and Subdivision Surfaces Figure 9.59: Ver- tices at level zero 4345c09_p3.1.qxd 1/1/05 1:52 PM Page 262 ■ Modeling the Face 263 Figure 9.60: Ver- tices at level 1 Figure 9.61: Edges at (left) level 0 and (right) level 1 4345c09_p3.1.qxd 1/1/05 1:53 PM Page 263 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 details that would normally be created by adding geometry, this command adds the detail without adding geometry. Usually it will not be necessary to go any finer than level 0 to use this command to cre- ate creases along the skin of the model. The edges along the lines that require detail are selected first. Figure 9.63 shows the edge of the eyelid highlighted, ready to use the Partial Crease Edge/Vertex command. 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 to the corner of the mouth. This character line usually animates quite a bit and is not an area where excessive detail should be added. The more complex the geometry in areas like this, the more likely it is that the blend shapes and facial animation rigs will have problems. Using the Partial Crease Edge/Vertex command is a perfect choice for creating this detail. As in the example shown in Figure 9.64, the edges along the area are selected before the command is executed (see Figure 9.65). When the command is executed, the line along the face is perfectly tightened. Using conventional 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). 264 chapter 9 ■ Advanced Character Modeling Using Polygons and Subdivision Surfaces Figure 9.62: (left) An unedited subdivision model and (right) an edited version 4345c09_p3.1.qxd 1/1/05 1:53 PM Page 264 ■ Modeling the Face 265 Figure 9.63: The eyelid line selected for the Partial Crease Edge/Vertex command Figure 9.64: The eyelid highlight line 4345c09_p3.1.qxd 1/1/05 1:53 PM Page 265 And our final model shows the results of our detailed work (see Figure 9.67). If you want to see the model in 3D, open subD_modeling_final_details12.mb in the CD. Always Learning We covered a lot of ground in this chapter—the process of creating a wireframe cage from an edge loop layout, the process of using the polygon-by-polygon modeling technique to create an organic model, and the process of using subdivision levels to create degrees of details. Subdivision modeling is quickly becoming the industry standard for creating beautiful organic models. These techniques are powerful and fast and are far superior to the tech- niques that preceded them. 266 chapter 9 ■ Advanced Character Modeling Using Polygons and Subdivision Surfaces Figure 9.66: Finished crease along the face Figure 9.65: Selected edge along the side of the face 4345c09_p3.1.qxd 1/1/05 1:53 PM Page 266 [...]... Learning 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... the little surface tweaks that bring the flesh to life The tools in Maya are only the pencils 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 creations than those you developed using the tools that you have been using before The flexibility and speed of polygon-to-subdivision modeling can... 181 smoothstep function, 216 soft bodies for car antenna, 180–183 creating, 181–183 soft body dynamics, 179 soft light, Final Gathering for, 102 Soft Modification tool, 172–173 handle, 173, 175, 176 Soft/Rigid Bodies menu, → Create Soft Body → ❒, 182 softness of Transform constraint, 20 Solver Scale for cloth, 10, 10 Solvers menu, → Initial State → Set for Selected, 204, 219 spaces in names, 131–133... Options → Keep Faces Together, 244, 245, 248 → UV Snapshot, 42 The Prince of Egypt, 58 printing, dpi (dots per inch) for, 43 priority of collision, 17, 17 professional animators’ secrets, 166 propagation of updates to all instances, 5 props designing, 114 lighting, 115–120 pseudorandom sequence of numbers, 210 Q quickSelectSet, 139 R radiosity renderings, 86 Global Illumination and, 103 and shadows, 95... 22–23 field of view (FOV), focal length of lens and, 63 Fields menu → Gravity, 212 → Radial ❒, 214 Fifty Percent Grey, 86 file format, floating-point, 86, 118, 120 File menu → Exit, 26 → Import, 115 → New Scene, 115 → Open Script, 9 → Source Script, 32 Final Gathering, 101 , 109 and direction of plane, 120 for directional lighting, 118 vs Global Illumination, 103 sample settings, 110 for soft light, 102 Finding... Akira, 37 ambient occlusion, 95, 95 102 baking out, 95–96 for droid, 96 101 , 97, 98, 99 compositing passes, 101 102 , 102 separate pass, 96 ambient occlusion shaders, 86 angle of incidence, 90, 90 angle of view, 63 Animate menu → 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 keyframed,... script to generate, 8 “locked-off” camera, 59 long names, 130 The Lord of the Rings, 1, 58 Low Dynamic Range Imagery (LDRI), 86 J Japanes anime, 37 Japanese katana sword, 108 –112, 112, 113 Jaws, 65 K katana.mb file, 110 keyable attributes, 148 M managed pipeline, 126 matchMove_handheld.mov file, 82 matchMove_tracked.mb file, 82 The Matrix, 1 matte surfaces, Fresnel Effect and, 92 Maya Live, capturing camera... computer, constraint display and, 20 Relax Frame Length, 10 relaxed garment state, saving, 12–13 Render Global Settings dialog box, 109 , 175, 175 ■ Render Global Settings menu → Mental Ray → Caustics and Global Illumination, 107 → Final Gathering, 107 → Quality Presets, 106 rendering See non-photorealistic rendering techniques research lab, IBL with Final Gathering to create, 114–120 Resilience attribute,... Visibility, 103 attributes See also specific names of attributes expressions to create new, 190 automatic 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, 145 Blend Colors shader node, 45 blocking, keyframes for, 75 bone edge loops, 234, 234 boom, 58 boom shot, 58 bounciness of cord, 176... 155–158, 157, 158 Octopus_finished.mb file, 158 Octopus_start.mb file, 155 off-angle shot, 59 off-camera character animation, 24 offset from collision surface, 17 one-node camera, 59 creating, 65 optimize scene command, 137 Orig nodes, 136 orthographic projections, 230, 239 Outliner, hierarchy of object, 130 Output Statistics, for cloth, 10, 10 P Paint Cloth Properties tool, 16 Paint Effects tool for curve, . 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. cre- ate creases along the skin of the model. The edges along the lines that require detail are selected first. Figure 9.63 shows the edge of the eyelid highlighted, ready to use the Partial Crease. a realistic appearance (see Figure 9.64). Another area that requires a crease is the line that extends from the side of the nose to the corner of the mouth. This character line usually animates