Shape from Shading


The Shape from Shading plug-in works by deducing height variations from the shading in an image. Shadows in the image can confuse the software, as can strong color patterns on the surface. Strong color patterns can be accommodated by using the Shape from Shading plug-in with images of a subject taken under different lighting conditions. In nearly all cases the Shape from Shading plug-in will produce results superior to the traditional method, and the tool works surprisingly well with less-than-optimal input images. However, the Shape from Shading Plug-in will not work in every case. Bump patterns can be touched up using the standard tools in Photoshop. The purpose of the Shape from Shading plug-in is to compute the height map of a surface when either one, two, or three different images have been input. Just as the name of the plug-in indicates, the shape is what will be computed. This shape will be computed from image(s) that contain some degree of shading. Hence the title Shape from Shading.

When using the CGSD Shape from Shading plug-in for Adobe Photoshop, the user first inputs one, two, or three photographs to the plug-in. These photographs should be placed under the Channels palette. When there is one photograph, you can convert it to grayscale, or use only one of the RGB channels. When there are two or three photographs, you will need to change the image mode to Multichannel. Each photograph must be converted to grayscale beforehand.

As one might expect, the quality of the height map rendered by the Shape from Shading plug-in increases proportionally with the number of photographs used. Also, the Shape from the Shading plug-in contains a tool that allows one to evaluate the quality of the height map rendered. This tool allows the user to compare the original image with an image that was computed based on both the height map and the light sources.

Tunnel.avi (4.5MB)
Animation of space ship going through a tunnel (seen at right) lined with rocks. Bump maps of the rock material were created by the Shape from Shading plug-in.

Plug-in demo (2.39MB)
Screen capture of the plug-in at work, using 3 picture image sources.

 

 


Copyright CGSD Corp. 2002