A Terribly Scratched Teapot

A terribly scratched teapot is a piece of scratched flat sheet. When the sheet is illuminated, a teapot appears, and observers perceive a three-dimensional surface as the specular reflection changes.

This "scratched 3D" technique creates a three-dimensional appearance on nearly flat sheets such as plastic films. It generates anisotropic reflection by forming scratches that refer to three-dimensional information modeled in the manner of computer graphics. The result is a three-dimensional appearance in arbitrary curved surfaces on real-world surfaces without holography or lenticular technology.

Technical Overview
A terribly scratched teapot was modeled as an ordinary teapot. The Z-buffer of the teapot was taken instead of RGB color channels in the rendering process and transformed into a gradient field in the diagonal direction. Then several small curved lines ware drawn using a method called "hedge hog illustration" that makes each curved line follow the direction defined at each position of the gradient field. The binary image of curved lines was substantiated as scratches on a metal plate using a photo-engraving plate-making system. Copies that reproduce the 3D appearance can be easily made with an embossing process.

Naoki Kawai
DaiNippon Printing
Kawai-N (at) mail.dnp.co.jp