Welcome to a page from my CG Archive. This page has not been updated recently and is being kept around as a "museum piece." Please excuse any broken links.

1996: Sean's Computer Animation: 2D / 3D

We have produced many animations combining 2D and 3D elements in the same scene. It is quite difficult to make the elements work together well so the 3D doesn't jump off the screen at you and shout "Big ol' 3D element comin' at ya!!"

Here's a good example of combining 2D and 3D elements in the same scene. The head and "arms" are 3D elements, while the body is a 2D cel. I rendered the arms, head body separately for a number of reasons:

Animated GIF - 36.6 K

The head and body elements were stationary, so only had to be rendered once, which saves rendering time.
Keeping the cells separate from the 3D elements avoided having to worry about them colliding or passing through each other.
The elements could be combined later in various ways, (flopping cels, changing the angles of the heads, etc), to produce more than one variety of character.
Since the arms are spinning, and the animation is lasting 10 seconds, a lot of rendered frames would normally be required. However, each arm is spinning six degrees every frame, so at thirty frames per second, six frames will have the arms moving 36 degrees. Multiply that by ten and you have 360. Therefore, only six different rendered positions are required to create the illusion of continuously spinning arms.

As for the other elements, all except the foreground character and the sky are 3D models created in Prisms. The shadow on the roof was created and animated in the Sidefx image compositer, "Ice."

goyocom.jpg - 23.6 K

bird.jpg - 17.4 K

Here's a scene from "Night Train to the Stars." Kenji takes his class out on a field trip and encounters an eerie tree housing a flock of Japanese "mozu," or shrike. The birds were modeled in Prisms, and then a simple flapping animation was created using a skeleton. The geometry files were saved in four positions, (the birds were flapping very quickly, no more than four different positions were necessary), and these were read into the final animation using a Read SOP and a spare channel. The texture was created in Photoshop. I added a dent generator to give the birds some roughness. Finally, the light paths were the birds flight paths used as a backbone for the Sweep SOP/Rail SOP combo, a cull SOP controlling their length and duration, a Polygon SOP to give the tapering effect, and a point SOP to provide colour and make the trails fade to transparent. The trails were rendered separately and then glow was added in Ice.

In this scene the birds are bursting out of a tree, scaring the bejeebers out of Kenji's students. There are three different sets of 10 paths, for a total of thirty birds and paths. I rendered the birds separately from the background, then copied, translated and scaled them in Ice, giving me about 120 birds. All this work and this scene lasted just over one second!!

This snowflake was modeled in Houdini and rendered in Prisms. I drew the "arms" of the flake on paper, scanned it, and then ran the image through a trace SOP. I added a point SOP with a random translation in the Z axis to make the edge jagged. Doing this created a crystal-like structure when it was extruded and faceted. Due to the extremely high polygon count, and transparent material, each frame took approximately four hours to render at first. This being clearly unacceptable, (client wanting it before the new millenium), massaging the texture and culling some polygons brought the times down to about 30 minutes a frame.