Mastering Autodesk Maya unfortunately only has two chapters on modeling, but I decided that I would work on those two chapters before moving on to shading and texturing. I will be going back to Introducing Autodesk Maya as soon as I complete these two chapters.
Modeling I
Vocab/Notes (Mostly Review)
Polygon Geometry: A surface made up of polygon faces that share edges and vertices.
Polygon Face: A Geometric shape consisting of three or more edges.
Vertices: Points along the edges of polygon faces, usually at the intersection of two or more edges.
Mesh: A series of faces that share two or more vertices.
Planar: When all the vertices of a polygon are along a single plane.
Non-planar: When the vertices are moved to create a fold in the surface.
According to the book it is best to keep polygon surfaces as planar as possible in order to avoid possible rendering problems, especially in game models.
Edge: The line between two polygon vertices.
Non-Manifold Surface: Geometry that can't be unfolded into a flat piece.
Examples include;
- When two polygons share a single vertex.
- Three polygons are extruded from the same edge.
- Two adjacent polygons with their normals pointing in opposite directions.
Manifold Geometry: The volume of the model is well defined, and has the following properties.
- Every edge belongs to two faces.
- Every vertex is surrounded by one sequence of edges and faces.
- Faces only intersect each other in common edges and vertexes
- There is a material on only one side of a face.
Face: The actual surface of a polygon.
Smooth Polygons: 1, 2, and 3 keys preview what the mesh will look like at certain subdivisions. 1 is at the lowest, and each operation up quadruples the number of faces and,increasing the number of vertices available for modeling.
The difference between a Subdivision Surface (subDs) and the Smooth Mesh Preview (1, 2, and 3 keys), is that the subdivision surfaces allow you to subdivide a mesh to add detail only where you need it. Example: Sculpting a fingernail at the end of a finger. There is not need to add that much detail to the entire mesh if you only need it at the tip of a finger.
When converting a polygon mesh into a subdivision surfaces keep in mind the following.
- Keep the mesh as simple as possible; converting a dense polygon mesh to a subDs significantly slows down performance.
- You can convert three-sided or n-sided (four or more sided) polygons into subDs, but you will get better results and fewer bumps in the subDs model if you stick to four-sided polygons as much as possible.
- Non-manifold geometry is not supported. You must alter this type of geometry before being allowed to convert.
NURBS: Non-Uniform Rational B-Spline
NURBS: A HISTORY
Early in the history of 3D computer graphics NURBS were used to create organic surfaces and even characters. However, now that computers have become more powerful and software has developed more advanced tools, organics and character modeling are most often accomplished using polygons and subDs. NURBS are more useful in modeling hard surfaces objects, such as cars and armor.
All NURBS objects are automatically converted into triangles during the rendering process. You can determine how the surfaces will be tessellated (converted into triangles) before render, and can change the settings at any time to optimize rendering. Models closer to the camera can have higher tessellations than ones farther away.
NURBS are always made of four sided patches, you cannot create a three or five-sided NURBS patch, which can limit the kinds of shapes you can make.
Parameterization: The way in which the points along the curve are numbered.
Uniform Parameterization: A Curve with Uniform Parameterization has its points evenly spaced along the curve.
Chord Length Parameterization: A proportional numbering system that causes the length between edit point to be irregular.
Bezier Curves: Use handles for editing as opposed to CVs. (Similar to Photoshop's Pen Tool?)
Apparently you can create curves in Adobe Illustrator and import them into maya. It sounds like it could come in very handy! According to the book it is most often used as a method for generating logo text.
A single NURBS model may often be made up of numerous NURBS patches that have been stitched together. However, when stitching patches together you need to be careful to have the same number of vertices in each direction so that it is consistent. At this level of technology polygons is a faster method.
Image Planes: Images attached to a Maya camera, which can be used as a guide for modeling or as a rendered backdrop.
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