This Animation was modelled in 3D Studio using a Viewpoint dolphin model and saved to an 3DS file. The line art rendering was done completely in our own system. This system (we don't have a name for it yet) is implemented in VisualWorks, a powerful Smalltalk environment.
The 3DS file was parsed into our internal scene representation. The animation component produced a transformed geometry for each frame. On this geometry an analytic visible line determination was performed yielding visible segments with shading information.
To draw the lines chains of segments were collected and transformed into controlpoints for the strokes. The lighting was translated into pen pressure producing wider strokes. Where a stroke vanishes behind an object the stroke was shortened to tell the objects apart. A little addition of noise adds interest to the static parts of the scene.
Each frame drawn was immediately appended to the final GIF animation file. To limit file size only one bit of color was used (click on the animation to view a high-quality frame produced by rendering to a PostScript file (50K) and letting Ghostscript do the rasterization). The rendering took twenty seconds per frame on a Pentium running at 100 MHz.