3D Modelling and Animation

3D Modelling and Animation

                                    Technically, 3 Dimensions refers to objects that are constructed on three plans (X, Y and Z). The process of creating 3D graphics can be divided into three basic phases: 3D modeling, 3D animation and 3D rendering. Three dimensional (3D) computer graphics are widely used and they are almost too common to see anywhere, let it be movies, products designs, advertisements, etc. Although they are commonly seen, that doesn't mean they are easily created. In order to interactively control a 3D object, it must be created in a 3D authoring tool which usually cost a lot to a non-professional user.

• Polygonal modeling
• NURBS modeling
• Splines & Patches modeling
• Primitives modeling
• Sculpt modeling

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OUTCOME OF 3D MODELLING & ANIMATION

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Character Modeling :

 
A 3D artist, who is expertise in a 3D modeling and animating tool, will examine the sketches and starts sculpting the figure using his imagination and skill. The software tool that the artist uses provides various approaches to perform the modeling. Usually organic modeling techniques like Polygonal Modeling (a polygon is subdivided to get the desired shape), NURBS modeling (curves are arranged to create a surface flowing through them), Sub divisional Modeling (A hybrid blend between polygonal modeling and NURBS modeling) are used. In these modeling techniques, the 3D modeling artist will sculpt out the characters shape in 3D using a set of tools provided by the 3D modeling software, by following any of the above mentioned approaches.

The 3D Model obtained finally will be in an editable form and the model will be dependent on the approach used. For example a NURBS technique will yield a 3D Model in the NURBS representation (curves and surfaces). Once the modeling is complete, the artist converts it into the basic polygonal mesh (vertices alone). The polygonal mesh is nothing but a huge number of polygons that are arranged so as it forms the whole character. This conversion to polygonal mesh offers many advantages like faster rendering speed, and multi-software compatibility.

Polygonal modeling - Points in 3D space, called vertices, are connected by line segments to form a polygonal mesh. Used, for example, by Blender. The vast majority of 3D models today are built as textured polygonal models, because they are flexible and because computers can render them so quickly. However, polygons are planar and can only approximate curved surfaces using many polygons.

NURBS MODELING:

NURBS Surfaces are defined by spine curves, which are influenced by weighted control points. The curve follows (but does not necessarily interpolate) the points. Increasing the weight for a point will pull the curve closer to that point. NURBS are truly smooth surfaces, not approximations using small flat surfaces, and so are particularly suitable for organic modeling. Maya, Rhino 3d and solid Thinking are the most well-known commercial programs which use NURBS natively.

Spines & Patches modeling - Like NURBS, Spines and Patches depend on curved lines to define the visible surface. Patches fall somewhere between NURBS and polygons in terms of flexibility and ease of use.

PRIMITIVES MODELING:

This procedure takes geometric primitives like balls, cylinders, cones or cubes as building blocks for more complex models. Benefits are quick and easy construction and that the forms are mathematically defined and thus absolutely precise, also the definition language can be much simpler. Primitives modeling is well suited for technical applications and less for organic shapes. Some 3D software can directly render from primitives (like POV-Ray), others use primitives only for modeling and convert them to meshes for further operations and rendering.

SCULPT MODELING:  

Still fairly new method of modeling 3D sculpting has become very popular in the few short years it has been around. There are 2 types of this currently, Displacement which is the most widely used among applications at this moment, and volumetric. Displacement uses a dense model (often generated by Subdivision surfaces of a polygon control mesh) and stores new locations for the vertex positions through use of a 32bit image map that stores the adjusted locations. Volumetric which is based loosely on Voxels has similar capabilities as displacement but does not suffer from polygon stretching when there are not enough polygons in a region to achieve a deformation. Both of these methods allow for very artistic exploration as the model will have a new topology created over it once the models form and possibly details have been sculpted. The new mesh will usually have the original high resolution mesh information transferred into displacement data or normal map data if for a game engine.

ANIMATION:

once the static elements have been set, the 3D artist applies motion to them. This process, called animation is performed by setting key frames. In order to animate a ball falling, the animator would set the first key frame at say 0th second with the balls position at the initial top position. He would set the next key at say 5th second with the balls position touching the ground. The 3D animation software interpolates the balls falling action between the 0th and 5th seconds. The animator can customize the interpolation behavior using graphs or by setting intermediate keys.

In Character animation, similar principles are applied. The skeleton will be animated by the animator and the 3d mesh skinned to the skeleton gets animated automatically. Character animation is often aided by plug-in tools (e.g.: biped) that has been created specifically for creating character animation sequences like walking or running cycles. The various scene elements, cameras and lights are animated using basic key-frame animation, based on the story board requirements.