Growing and Animating Polygonal Models of Animals
Here follows a brief explanation on how we created the animations
for the horses and cows (below). The full technique is explained in a
paper
(Gzipped Postscript - 434K) presented at
Eurographics'97.
- We first start with the model we want to simulate growth or
animate. In this
case the model is defined as a polygon mesh without any structural
information. We are using models from
Viewpoint.
On top of this model we define a set of primitives
(in this case cylinders) for each part of the body that we
want to individually grow or animate.
- If we want to simulate growth, we have to define the features of
the object, that is, pairs of straight
line segments which represent the measurements made in the real animal
and will later drive the change in the cylinders. In the picture below
we don't show the cylinders for clarity but both are applied to
the model at the same time.
- Once the basic structure of primitives and features is defined
we can start the simulation. In order to simulate growth we
changed the size of the features according to growth data, usually collected
from Animal Studies literature.
- In order to simulate animation, we gathered animation information like the
ones provided by Muybridge pictures. In the picture below we show one
frame from Muybridge where we measured the angles between the joints
on the leg. These angles were used to position the cylinders to
produce the animation of the horse trotting.
Animations (SGI format)
Animations (MPEG format)
If you are viewing these animations on a PC, you should try to use
the mpeg player called vmpeg, available free from
www.mpeg.org/~tristan/MPEG/MSSG/
This page has been accessed 
times since 27 August 1997.
