“Merging and transformation of raster images for cartoon animation” by Wallace

The task of assembling drawings and backgrounds together for each frame of an animated sequence has always been a tedious undertaking using conventional animation camera stands and has contributed to the high cost of animation production. In addition, the physical limitations that these camera stands place on the manipulation of the individual artwork levels restricts the total image-making possibilities afforded by traditional cartoon animation. Documents containing all frame assembly information must also be maintained. This paper presents several computer methods for assisting in the production of cartoon animation, both to reduce expense and to improve the overall quality. Merging is the process of combining levels of artwork into a final composite frame using digital computer graphics. The term “level” refers to a single painted drawing (cel) or background. A method for the simulation of any hypothetical animation camera set-up is introduced. A technique is presented for reducing the total number of merges by retaining merged groups consisting of individual levels which do not change over successive frames. Lastly, a sequence-editing system which controls precise definition of an animated sequence, is described. Also discussed is the actual method for merging any two adjacent levels and several computational and storage optimizations to speed the process.

1. Catmull, Edwin, “A Hidden-Surface Algorithm with Anti-Aliasing”, Computer Graphics, volume 12, number 3, August 1978.
2. Catmull, Edwin, and Smith, Alvy Ray, “3-D Transformation of Images in Scanline Order”, Computer Graphics, volume 14, number 3, August 1980.
3. Levoy, Marc, Computer-Assisted Cartoon Animation, M.S. Thesis Cornell University, August, 1978.
4. Levoy, Marc, and Feibush, Eliot, and Cook, Robert, “Synthetic Texturing Using Digital Filters”, Computer Graphics, volume 14, number 3, August 1980.
5. Madsen, Roy, Animated Film: Concepts, Methods, Uses, New York, Interland Publishing Inc., 1969.
6. Smith, Alvy Ray, “Tint Fill”, Computer Graphics, volume 13, number 2, August 1979.
7. Stern, Garland, “SoftCel – An Application of Raster Scan Graphics to Conventional Cel Animation”, Computer Graphics, volume 13, number 2, August 1979.