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SAE Magazine 12-2

Two dimensional and incompre- hensible If you have already taken the first steps with Au- todesk Maya then you are already aware of the main working steps which are required to produce animations: modelling, texturing, lightning, ani- mation and rendering. In all likelihood you will have many failed attempts before you correctly understand how to quickly and optimally create UVs. When you are however in the happy position that you no longer need to have any unnecessary worries about this topic you will have reached an important milestone for your future 3D masterpieces. Polygons, NURBS and subdivision objects Primitives Primitives are any objects which can be created in Maya as output objects. Sphere, cube, plane, cyl- inder, cone and torus are the basic forms which are good starting points. Regardless of what end form is required you must also decide which object type will be used to con- struct this with: Maya gives you the choice of poly- gon, subdivision and NURBS objects. For all of these three types of objects the representation may either be edged or rounded. This is called the vari- ous SubdivDisplaySmoothness states. In order to change back and forth between these display types in Maya use the numbers “1” to “3” on your key- board. Figure 1_ NURBS, polygon and subdivision spheres (L to R) at smoothness level 1 The higher the number (max 3), the smoother the form of the object. In the two illustrations both ex- tremes are shown with smoothness level 1 (Figure 1) and 3 (Figure 2). Figure 2_ NURBS, polygon and subdivision spheres (L to R) at smoothness level 3 Polygon objects Polygons are made out of faces. Each face is a flat surface which is in turn bordered by vertices (poly- gon points). If three vertices are combined a three- sided face is made, if four vertices are combined, a four-sided face is made. Three-sided faces are called triangles, four-sided ones quads. Each line formed between two vertices which at the same time forms the edge of a face is called an edge. If a vertex is moved in a particular direction the edges and the corresponding face will adapt. NURBS objects Non-uniform rational basic splines (NURBS) are made up of Bézier curves which can be used to en- hance round forms. The surfaces with NURBS are called patches, the control points control vertices (also called CVs) and the edges isoparms. As op- posed to polygon objects, round NURBS objects do not have the CVs on the ends of the isoparms because these are comprised of mathematical av- erages. This has the advantage that the flat forms are relatively easy to create. A similar round poly object would have many more faces - and more faces means much more work. A NURBS standard object is always comprised of one (e.g. NURBS plane, sphere, torus) or multi- ple objects (e.g. NURBS cube, square). Therefore when creating a NURBS cube an automatic group with the name of the object is created in which the required indivi dual objects can be found. Our NURBScubewillbemadeupofsixNURBSplanes which can be found in the group “nurbsCube01”. Subdivision objects Thecombinationiscalledsubdivision(alsosubDs). Subdivisions combine the advantages of polygon and NURBS objects: they can be quickly mod- elled with edges and then in two steps can be made flat or even round. The key to this lies in the level of detail. These produce a division of the existing faces which can in turn be used to be able to model in more detail. ➤ 110 Production & Know How // TEXTURING Index

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