View Full Version : 3d newbie definitions questions

 exovoid08 August 2005, 08:25 AMI'm just getting into 3d now, and I keep seeing terms I don't understand, please direct me towards another thread if there is one, I couldn't find it... The words I'm after definitions/descriptions for are polygon modelling Sub-d NURBS UV Mapping and one which i cant remember the term for... rigging a model? Thanks, sorry if this is just another n00b
AA_Tyrael
08 August 2005, 10:41 AM

exovoid
08 August 2005, 10:45 AM
actually no, it's not, if you've heard of a thing called websense you'll know the hell it causes while trying to do anything constructive on the net, I'm unable to use google from where I am, admin has decided it's a threatening resource... don't ask me why.

rybeck
08 August 2005, 01:51 PM
exovoid,

These are raw definitions of terms you were asking, and these are from Maya Help (which is available from S/W)...
One thing I have in my mind is that you need to get a reference or two (probably one of "introduction of Maya...") to read about the material... I am afraid of the question you asked is too general to get appropriate answers...
You can also try PLE version of S/W that available from Alias website...

Good luck...

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Polygon

A polygon is an n-sided shape, defined by its corners (vertices) and the straight lines between them (edges). When you model with polygons you usually use triangles or quadrilaterals ("quads"), although Maya supports polygons with more sides. An individual polygon is often called a face, and is thought of as the filled area defined by its vertices and edges.

Subdivision surface
Modeling with subdivision surfaces is an easy way to create intricate objects such as human hands. It combines the best features of NURBS and polygonal modeling.

Subdivision surfaces allow you to use a single surface to model complex shapes. A single subdivision surface can have different levels of detail in different regions. That is, a region that has a complex shape can have more control points to allow finer detail, while a simple or flat region needs fewer control points.

How it works

Subdivision surfaces get their name from this dividing into regions of greater detail. You start with a base mesh and divide and subdivide regions into finer and finer detail, with each subdivision giving greater control in that area.

You reshape subdivision surfaces by modifying control points at the different levels of the hierarchy. The base mesh (or "level 0" mesh) allows you to reshape large areas of the overall surface. The subdivided levels allow finer control in specific regions of the surface.

Subdivision surfaces allow higher level control over shape than polygons.
They allow you to only use complex geometry in the complex regions of your model.
They allow creases (sharp edges) and arbitrary topology (not just four-sided sheets).
The continuity of subdivision surfaces eliminates many of the problems that can occur at seams when you animate NURBS surfaces.
You can bind subdivision surfaces to skeletons at a coarse level and the effects will translate smoothly to the finer levels.

NURBS
NURBS stands for Non-Uniform Rational B-Splines.

Non-Uniform refers to the parameterization of the curve. Non-Uniform curves allow, among other things, the presence of multi-knots, which are needed to represent Bezier curves.
Rational refers to the underlying mathematical representation. This property allows NURBS to represent exact conics (such as parabolic curves, circles, and ellipses) in addition to free-form curves.
B-splines are piecewise polynomial curves that have a parametric representation.

UV
UVs are points that correspond to polygon vertices, but live in the 2D world of the texture. They control which points (pixels) on the texture correspond to which points (vertices) on the mesh.

Although Maya creates UVs by default, in many cases, you'll need to rearrange UVs because the default arrangement will not match the modeling changes you make. Typically, you arrange UVs after you have completed your modeling and before you assign textures to the model.

UVs are arranged in a 2D coordinate system called texture space. You can see the texture space coordinates in Maya's UV Texture Editor (formerly called Texture View). For example, the following illustration shows the default UV arrangement for the model of a fish. When a texture is assigned using this default UV arrangement, the result is haphazard.

Mapping

To begin rearranging UVs, you first need to assign them to the surface, known as mapping UVs. You'll learn how to map UVs in this chapter.

Polygonal surfaces have their own mapping and editing operations, separate from the subdivision surface operations. There are numerous mapping operations available, under the Edit Polygons > Texture menu.

To create a UV mapping arrangement that works best for your model, you may need to map several times, using various mapping operations, until you find a mapping arrangement that is suitable. See the following guidelines.

Rigging

Before animating the characters and objects in your scene, you set up your scene by rigging all your characters and by applying the appropriate constraints and deformers to all the objects you want to animate.

Rigging a character, also known as character setup, involves creating skeletons and IK handles for your characters, binding skins to the skeletons, and setting up deformers and constraints. You can also create deformers for your character and animate them to produce effects; for example, the jiggling belly (jiggle deformer), furrowing brow (wire deformer), and flexing biceps (lattice deformer) of a sumo wrestler model.

Non-character objects are also very important to bringing your scene to life. You can limit and control the transformations of objects by constraining them to characters or other models in your scene. You can also create deformers for objects to create complex deformation effects. For example, you can apply a squash deformer to the model of a ball and then parent constrain the ball to the hands of a character. With this setup, you can key the weights of the character's hands and the squash deformer's attributes to create an animation of the character bouncing the ball from hand to hand while the ball squashes on the ground and stretches as it rises back into the air.

In addition to setting up characters and objects for animation, you can set up dynamics for animation. You can constrain dynamic objects such as particle emitters, fields, and fluids to objects or characters in your scene. For more information, see the Dynamics and Fluid Effects guides.

(credit: Maya 6.5 HELP )

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exovoid
08 August 2005, 06:00 AM
thanks, as I don't have access to maya help I couldn't do that myself, but that cleared a lot up.

rybeck
08 August 2005, 04:04 PM
exovoid,

you can get PLE version from this link (http://www.alias.com/glb/eng/products-services/product_details.jsp?productId=1900003), and it is free...
There are some restrictions but it is worth playing around.

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