Are there any practical use cases for integrals higher than 5D for graphics?
If I'm not mistaken I think Ren mentioned something about having infinite integrals because ray tracing is a recursive operation. Each ray bounce requires another integral. So I think there are plenty of situations where integrals are chained together to form "technically" higher than 5D integrals.
How is it integrating over the 2D lens pupil vs the 2D pixel?