This tutorial provides an overview of some advanced polygon modeling and texturing techniques for Maya 4.0. It is my opinion that polygon modeling is the best way to sculpt complex organic shapes. (Special thanks to Dirk Bialluch who wrote a MEL script called "Connect Poly Shape" which allows you to quickly set up and sculpt a simple model while simultaneously seeing "the same" smoothed shape as it changes. This MEL script is free and can be downloaded from Highend3D.com.
This tutorial assumes that the reader possesses a basic knowledge of Maya polygonal modeling tools as it does not provide in-depth detail for every mouse-click, but rather an overall approach.GEOMETRY
In this tutorial, I chose to create a very old witch from traditional Russian folklore. She is called "Baba Jaga" and is a lonely woman living in the deep forest in a small wooden house and is constantly doing bad things to other heroes of Russian legends.
First, I sketched the character in pencil because I didn't want to restrict myself to a fixed image until I had a good idea of what I wanted. I prefer to play with proportions and shapes on-the-fly. As a result, I didn't put the sketch in ImagePlane, but kept it in front of me for occasional reference.
I created only one half of the model and used mirroring for to complete the basic model object. I first determined the right proportions, then created all of the remaining parts.
Next, I drew contours of all parts of the model in Side viewport (e.g., head, blouse, skirt, and shoes
), then extruded them out so that the contours defined my solid surface.
I deleted the faces laying in original plane and applied the connect PolyShape script with "Mirror and Stitch" option set to the "-X" direction, "Stitch" checker box set ON and "Smooth Geometry" parameter set to "1". Then using "Split Polygon Tool" I added more details making the shape more rounded. Using the "Extrude Polygon" tool, I made a very rough shape of the arm. The hands were modeled as separate objects to make easier to modify their geometry.
Next came the process of splitting polygons and vertex-tweaking to add details. It is very much like sculpting, when you remove all unneeded clay and add more and more details to obtain the ideal shape.
During this process, a very useful trick is to hide all unneeded objects using "View Selected" command from "Show" menu in viewport panel.
I also found that viewing objects in Smooth Shade All mode provides more information about how the final geometry is smoothed and allows you to clearly see where edges need to be added and what can be deleted.
The duration and instensity of this phase depends on where you use your geometry and how close to the surface you're going to show display it.
Some of the mesh details can be substituted by textures, say such as small wrinkles on the face. Making all of the details at render-time using a texture channel allows you to keep the polygonal count low. This technique is most often seen in 3D real-time rendering games.
In the this case, I was planning to make fairly close-up renderings, so I thought it best to make almost every detail using geometry rather than the quicker, texture channel method.MAPPING AND TEXTURE CREATION
Once the geometry is finished it is time to create mapping and shaders. Creating mapping for original geometry can be tricky as UV points are created for "Smoothed" geometry as well.
There are many ways to make create good mapping. The following is the method that works best for me. I wanted all UV points to be sewn into the smallest number of pieces, preferably one or two to make painting textures more correct and accurate later. In addition, if there will be additional editing later in the process (for instance, in Photoshop
), it is much easier to identify which texture image piece corresponds to the model.
Beginning with the head, I opened the "UV Texture Editor" window (ctrl-T
) with the head model selected (original, not smoothed
). This highlights all of the UV points. I used the "Automatic Mapping" command and tried using different numbers of projecting planes in its options dialog. I found that when the number of planes is set to 4, fewer pieces are created, which is what I wanted.
Next, I sewed the pieces together. Switching to the edges selection, I started from the region of the head that corresponds to face. I started here because these are the most important UV points for me. I then selected the border edges of the biggest part of the UV network I and used the "Move and Sew" command. One by one, I gathered all lost pieces of the UV network. I then used the "Relax" command several times on some of the UV points to make the network more regular. Finally, I used "Normalize UVs" to fit all the entire network into the "0 to 1" UV space.
Creating the UV maps can be a cumbersome process, but I find that it is not as slow as it seems, and it works well and gives very accurate results.
It is very important to remember that the further the UV points are each from other, the bigger part of image is put between them. For example, the eyes and the nose are the most prominent and therefore important parts of a face, so it makes sense to give them more of the image space than the other parts of the face mesh. Another example of relative importance is the cheek, which is much bigger than the eye but since it is plain and without detail you could give it less of the texture map. If you simply apply mapping according to geometry vertices you will get a large UV space for the cheek and a small one for the eye, which is a waste of texture. Keep this in mind when making corrections.
I created mapping for the other objects in a similar fashion. I used the "Automatic Mapping" command only for complex geometry such as head or hands. For the kilt and apron I used the usual "Cylindrical mapping".
Once the mapping is done, it's time to create shaders and textures. I believe the Maya "3D Paint Tool" with its ability to use Paint FX brushes is more than enough to draw a good texture. In fact, in this image I didn't use any extended applications to create the textures -- everything was done inside of Maya -- the only exception was using photographed textiles to create textile patterns!
The subject of creating textures is beyond the scope of this particular tutorial, however, there are a few tips I can provide:Give accurate and descriptive names to objects and shaders, it helps to keep order in texture files.
Don't use JPEG textures if you need good quality final renderings. JPEG compression changes the original colors of an image and you might be surprised when doing close renderings to find that you get color spots on an originally flat surface! Using TIFF textures offers more accuracy and better rendering quality though TIFFs take up much more space on your machine.
Final colors created out of many passes and layers are more alive and beautiful, and subtle.
Start with big color spots and gradually add more small details.
Don't use Black –- use close colors -- say, very dark blue or dark brown.
Make detailed dark spots and regions in the last step.
Always give attention to obtrusive parts, or prominent parts that "stick out," with brighter colors since that helps show the shape.
When drawing bump textures, it is helpful to do test renderings to see how they work together with color textures.
Finally, map the "Incandescence" of almost all shaders with the "U Ramp" node, and the "U coord" parameter connected to the "Facing Ratio" parameter of the "Sampler Info" node.
After finishing with shaders, I created hairs and eyebrows using the "Paint FX" tool. To make strokes align accurately with the geometry, I was forced to create additional NURBS surfaces to use them as "Paintable objects" ("Make Object Paintable" command under the Paint Effects menu
). Unfortunately only NURBS objects can be made paintable.
To create the NURBS surfaces, I made the Head object "Live", and then drew several curves near the eyebrows and regions where hairs would be seen. I then used the "Loft" command to create reference surfaces that could be used as "Paintable Objects" during later editing.
After all the strokes were painted and I was happy with their shapes, I attached them to one brush node using the "Share One Brush" command. I then tweaked their parameters to achieve the desired look.
That's it for the creation of the actual mesh!
The rest of the image entails setting up the environment, a lighting scheme, a skeleton and character rigging to give her a natural pose and, of course, the rendering!
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