「ai sp@ce」 のバイトは、どうしますか? (Activity # 17)

This activity focuses on photometric stereo, a method of extracting shape and surface detail from shadows. Using this method, we are able to reconstruct an image with surface detail from a series of several images taken at different point sources.

Suppose we have the matrix V given by

where the first index of V represents the image while the second index refers to x, y, and z coordinate of the light source respectively. Assuming these sources illuminate a common object of interest, we can obtain a series of images with intensities defined by

for each point (x,y). We would then have to find g for each point using the usual matrix operation (i.e. inv(V'*V)*V'*I) and normalize the g's to obtain the value for the normal vectors. We get the surface normals using

and finally, we obtain the surface elevation at a point (u,v) using

Following the steps I listed above, here's the Scilab output for the images contained in Photos.mat

I'd like to give myself a 10 for this activity, since this is one of the RARE activities that anyone can finish in one meeting. xD