1	Announcements Project 2 due today Project 3 out today demo session at the end of class
2	Photometric Stereo Readings Forsyth and Ponce, section 5.4
3	Diffuse reflection
4	Shape from shading Suppose
5	Photometric stereo
6	Solving the equations
7	More than three lights Get better results by using more lights
8	Color images The case of RGB images get three sets of equations, one per color channel: Simple solution: first solve for N using one channel Then substitute known N into above equations to get k_d s:
9	Computing light source directions Trick: place a chrome sphere in the scene the location of the highlight tells you where the light source is
10	Recall the rule for specular reflection
11	Computing the light source direction Can compute N by studying this figure Hints: use this equation: can measure c, h, and r in the image
12	Depth from normals Get a similar equation for V₂ Each normal gives us two linear constraints on z compute z values by solving a matrix equation (project 3)
13	Project 3
14	Limitations Big problems doesn’t work for shiny things, semi-translucent things shadows, inter-reflections Smaller problems camera and lights have to be distant calibration requirements measure light source directions, intensities camera response function
15	Trick for handling shadows Weight each equation by the pixel brightness: