Describe different 3D modelling techniques used in digital art… 800 words… reference and cite at least 4 scholarly texts to support your findings…. Elements to discuss may include common toolsets, common terminology, modelling workflow options. limitations of different surface types or typology requirements for deformation.
Modelling requires a balance of quality and speed. The more complex the model the longer it will take to build, the more polygons it has the longer it will take to render (Danaher, the Complete Guide to Digital 3D Design, 2004) Movie models can be generated with millions of polygons using several different techniques at once. Gaming models have to be more efficient. Lower poly assets will render more smoothly and give better frame to frame renders during game play. (Dargie)
Maya uses 3 types of modelling polygons, NURBs and subdivision surfaces. (Derakhshani, 2011)
NURBS is short for “Non Uniform Rational Bézier Spline”. (Linden Research, Inc., 24) Unlike polygons NURBS are resolution independent, they are controlled by fewer points called control points. (Danaher, the Complete Guide to Digital 3D Design, 2004)
The splines (for drawing curves) within NURBS modelling can typically be controlled easily and manipulated, and their structures are influenced by control points, drawing the curves in particular directions. One of the primary advantages to using NURBS is that smooth curves can be achieved (Smith)
They are particularly suited for modelling in 3D, because they provide excellent continuity with a minimum number of control points (Autodesk Maya, 2012)
You can create a NURBS model only 1 way with a grid of NURBS curves, like moulding a wire mesh. You can’t extend this rigid topology surface like a polygon one, but you can add extra geometry, blend between 2 surfaces, adding a new surface between with both ends matching perfectly with the originals. You can project curves onto surfaces to deform and build off them. However you can’t cut holes in them because they are so rigid, only the tessellated version of them can appear to have a hole. (Danaher, the Complete Guide to Digital 3D Design, 2004)
Polygonal Modelling is a versatile technique. Polygons can be either simple shapes, such as polygonal primitives, or complex models built from the various polygonal tools. A polygonal object can be closed, open, or made up of shells, which are disjointed pieces of geometry. Also known as mesh. (Autodesk Maya, 2012)
The Polygon Mesh is the most common modelling method used in 3D computer graphics. The process involves the direct manipulation of polygons- triangles and quadrilaterals (the one to avoid if possible is the ngon (a polygon with more than four sides) – these can cause problems in some programs and lead to issues if they’re subdivided). (tips-and-tricks-for-organic-modelling, 2012). The process also involves the manipulation of faces, vertices and edges to produce the desired shape. (Linden Research, Inc., 24)
The modelling process involves the combining, dividing and extrusion of these polygons to create a structural model. An advantage to using polygonal techniques is that computer programs are generally able to render them effectively and fast. A disadvantage to polygonal modelling is that curves cannot be accurately represented. (Smith)
While the arbitrary nature of polygonal surfaces provides great freedom and flexibility it can lead to invalid or non-manifold geometry in creating surface topology.
A non-planar face (where at least 1 of the vertices is on a different plane to the others) may not render correctly or transport well to a game engine. (Danaher, digital 3D Design- the use of 3D applications in digital graphic design, 2001)
Manifold geometry is faces that can be cut and folded, non-manifold can’t. The 3 types of non-manifold are: T-shaped- 3 faces share a common edge, Bowtie- 2 faces share a vertex but not an edge, Reversed normals-2 faces sharing an edge have opposing face normals (Danaher, digital 3D Design- the use of 3D applications in digital graphic design, 2001)
Lamina faces share all the same vertices and edges, they are essentially laminated together but are incorrect geometry.
Mesh – cleanup– a tool set option, is an excellent tool for dealing with non-planar, non-manifold geometry, lamina faces and other unwanted polygon issues. (Danaher, digital 3D Design- the use of 3D applications in digital graphic design, 2001)
Subdivision Modelling involves techniques that are applied to an already existing model and has some of the features of both polygonal and NURBS modelling.
The outer cage acts like a poly object so all the poly tools can be used on it but it needs only a fraction of the polygons to create a very high resolution, smooth surface with lies under the cage. SubdDs allow you to subdivide a mesh to add detail only where you need. (Keller, 2010)
If you start with a NURBSs or subdivision surface in the end it is preferable to convert everything to polygons. (Derakhshani, 2011) At render time all geometry of every type is converted to poly triangles. Tessellation refers to the number and placement of the triangles on the surface when the scene is rendered. Objects with low tessellation will appear blocky but will have a shorter render time than hi tessellation objects. (Keller, 2010)
Generally speaking it’s best to model in quads. Quads (quadrangles – four-sided polygons) are predictable and subdivide in a clean way, leaving less chance for bad artefacts at render time. (tips-and-tricks-for-organic-modelling, 2012)
Autodesk Maya. (2012). Autodesk Maya help. Retrieved 12 3, 2012, from Autodesk Maya: http://download.autodesk.com/global/docs/maya2012/en_us/
Danaher, S. (2001). digital 3D Design- the use of 3D applications in digital graphic design. London: Cassel and Co.
Danaher, S. (2004). the Complete Guide to Digital 3D Design. Cambridge: the Bex Press Limited.
Dargie, J. (n.d.). Modeling Techniques: Movies vs. Games. Retrieved 12 3, 2012, from ACMSiggraph: http://www.siggraph.org/publications/newsletter/volume-41-number-2/modeling-techniques-movies-vs-games
Dargie, J. (n.d.). Modelling Techniques Movies vs Games. Retrieved Dec 3rd, 2012, from ACMSiggraph: http://www.siggraph.org/publications/newsletter/volume-41-number-2/modeling-techniques-movies-vs-games
Derakhshani, D. (2011). Introducing Autodesk Maya 2012. Indianapolis: Wiley Publishing.
Keller, E. (2010). Matering Autodesk Maya 2011. Indianapolis: Wiley Publishing Inc.
Linden Research, Inc. (24, Jan 2009). Sculpted Prims: 3d Modeling Glossary. Retrieved 12 3, 2012, from Second Life Wiki: http://wiki.secondlife.com/wiki/Sculpted_Prims:_3d_Modeling_Glossary
Smith, S. (n.d.). 3-D Modeling Techniques. Retrieved 12 3, 2012, from eHow tech: http://www.ehow.com/list_7505857_3d-modeling-techniques.html#ixzz25BW8P3bF
tips-and-tricks-for-organic-modelling. (2012, 07 19). Retrieved 08 18, 2012, from 3dworldmag.com: http://www.3dworldmag.com/2012/07/19/tips-and-tricks-for-organic-modelling/