I can tell you about the renderers and a bit about modelling...

OK, scan line, most commonly used and also sometimes in combination with
raytracing (although the raytracer in the scan line renderer is usually held
within the texturing function...).

Raytracing by itself is not common in high end packages.

Radiosity, well, we all know about this, it's also sometimes incorporated
into scanline renderers (instead of raytracers)

Photon tracers (same as above)

There are some other renderers that just work on atmospheric systems but as
far as I know there are not many of them and they are generally used for
special effects overlays.

You'll find the big companies like ILM, Pixar, Dreamworks etc etc have their
own renderers.

Sub groups of rendering technology:

Atmospheric Fur Simulation, this is something that's pretty new.  What it
means in that it uses a special type of atmosphere (or media, whatever the
specific program calls it) to create the look of fur on an object.  A lot of
the time this method yeilds excellent results and you only have to look at a
Coca Cola comercial to see that!!!  (the ones with the bears anyway :)

When it comes to animation, a new technique has been using "fluid motion"
otherwise known as "soft selections"...  Basically what this means is that
once the model has been built you place certain bounding boxes around
specific parts of it and then give it a set of resistence values.  Then when
you animate or keyframe the object, it will automatically deform the object
based on the boxes (for example, you could use this to make a dog's ears
flop around as it walked).

Dynamics systems are also becoming more common in animation.  The idea is to
set up the object in the scene and give them physical properties like,
density and/or mass (the program will usually calculate this for you anyway,
based on bounding boxes, spheres, cylinders, or mesh grid degradation),
sliding friction, static friction, bounciness (for lack of a better word).
Then effects are applied and object collisions assigned... effects include
gravity (the most common), wind, drives, turbines, forces (general
directional forces) etc etc.  Also linkages are assigned through IK.  The
Dynamics system can then calculate the object collisions etc etc...

NURBS modelling is very complex.  It is part of nearly all high end systems
and allows the user to create very complex and organic models that have
adaptive degradation.  They use splines to create surfaces and from there,
there are many ways to go about clipping sections etc... some of the method
for creating surfaces are sweeps, extrudes, rail sweeps, bi-rail sweeps,
offset surfaces, blend surfaces etc etc.  NURBS are usually classified into
two parts, point NURBS and CV NURBS.  Both have their advantages and
disadvantages, and the main difference is the way in which the surface is
calculated based on the spline points (whether it averages the points, or
whether it makes the surface pass through each point).  Weighting can be
applied to a point individiually...  Curve approximation can be either
adaptive, steped or optimised.  The surface itself is approximated by a
number of methods and degradated from there using one of the following:
Grid degradation (uses a grid array to find the points which lie on the
surface), angle degradation (uses a minimum and maximum angle to work out
where it has to interpolate the surface more), ISO degradation (I don't
understand this one so I wont try to explain it in great detail, but it is
to do with the surface continuity).  As I said, they're complex...

Particle systems are becoming more advanced.  The newest development (which
was used first in such movies as Dante's Peak and Volcano) is a method of
combining atmospherics with particles.  The way it works is that it builds a
small atmosphere around each particle in the system.  Each atmosphere reacts
to the particle's movement, speed, direction, rotation and life (for
example, changing color or density over time).  This can be used to make
VERY advanced looking dust and smoke streams as well as fire and lava.

OK, that's it from me for the moment, I can tell you heaps more (and I will)
but I've got to go to school!!!

--
Lance.


---
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