Hmmm, yes, though they do say "In this paper we focus on primary (camera) rays, i.e. rays with a common origin or parallel rays, because only these are also cov

Hmmm, yes, though they do say "In this paper we focus on primary (camera) rays, i.e. rays with a common origin or parallel rays, because only these are also covered by rasterization. We consider secondary rays and efficient global illumination algorithms, such as path tracing or photon mapping, as orthogonal to our approach." Just what that "orthogonal" means is a bit mysterious, but their project seems to be to generalize rasterization further than they've got in this paper: "we aim for further generalization, in particular, a parameterization which allows for incremental computation, not only for the ray direction, but also the ray origin"