some fomula problem

This is what I have to do:

cost(edge) = clen(edge) * cang(edge)^a * cdist (edge)^b * cvis(edge)^g * cdot (edge)^d

(1)Length of edge. This I have done already.

(2)dihedral angle. Don’t really know what it means here.

(3)maximum distance (d) from the centerline of the stroke to the screen space
projection of the edge. (cdist (e) = (r-d) / r). I just do not noe whats the d.

(4)on a loaded mesh, how Do I determine whether a vertex is visible or not? The purpose is that for an algorithm to work, I have got to set the weight of an edge to 1 if its visible and 0.5 if its not.

(5)dot product of the viewing direction and the edge normal (average normal of 2 vetices)
cdot (e) = (1+V .N)/2)

Basically this is from the siggraph paper titled “modelling by example”. by Thomas Funkhouser.
Really thank you for the help, as I really tried my best on doing but still cannot understand it.