I'm currently working on an analysis of a special dome in a church in Rome: The St. Ignazio dome. In this picture I have already provided my analysis as for the vanishing point and vanishing line. From the entrance of the church it appears as if it has a dome, but this dome is just a smart illusion by making use of projective geometry and it's actually on a flat surface
My problem is: How do I go about making such an illusion myself? How do I project a hemisphere on a 2D surface and make it appear as if it's still a hemisphere?