I'm looking into the section "Reconstructing an object from its shadow" in the book Introduction to the Mathematics of Medical Imaging by Charles L. Epstein.
I have two questions
- The tangent point is expressed as a vector which contain two component. The shadow function $h$ multiplied with the orthogonal vector and an $s$ function multiplied with the direction vector. Can anyone tell me why do we have this equation, and what does the $s$ function mean?
- And also why do we have $h'D(e) - s(e) = 0$ when it is parallel to the direction vector $\hat \omega$?