Shape from shading
Suppose
You can directly measure angle between normal and light
source
•Not
quite enough information to compute surface shape
•But can
be if you add some additional info, for example
–assume
a few of the normals are known (e.g., along silhouette)
–constraints
on neighboring normals—“integrability”
–smoothness
•Hard to
get it to work well in practice
–plus,
how many real objects have constant albedo?