Part 1: Gereral Overview

Geometric Surface Types

Finally you will need to assess whether this character has any special dynamic systems interacting with it, such as particles, hair, fluid, fur, voxels etc. Knowing this information can contribute to determining what type of geometry your final model will be output as.
Not all geometry types are compatible with all dynamic systems. Many 3D applications could have atleast three types of surface geometry,

• NURBS (Non-Uniform Rational B-Splines)
• Polygons
• Subdivision Surfaces

Of these three surface types polygons is the oldest and most established technology and therefore most compatible across platforms and different 3D packages. An unfortunate side-effect of the latest technologies in 3D will, likely, result in the technology being least compatible across different 3D software packages.
Each surface type has its own field of excellence for example,

• NURBS for their precision and ease of use make them an ideal choice for many product and industrial designers.
• Polygons for thier versatility and highly interactive feedback make them a great choice for experimentation through to final output.
• Subdivision Surfaces can often have a specialized or propriatry toolkit for organic modeling and a non-destructive modelling stack making them an ideal choice for high definition, interactive and effecient character modeling.

With all of these choices the question begs, which one to use?
In actual fact you do not have to limit yourself to one geometry type as many 3D applications will allow you to convert between differing geometric types.
However, be aware that the conversion process between each of these different geometries will often result in destructive processes. In other words switching back and fourth between the different surface types may result in some degree of data loss. Although, the conversion between different surface types can be particularly accurate, this is often at the expense of generating a higher resolution model.