Top: geometry used in the analytical test cases. The z-axis is toward the reader. For test case 1, a central point source illuminates thin slabs of electrons that are slanted by 45° toward the observer. The central source is replaced by a small blob of electrons for the other test cases. The blob is illuminated by a collimated beam from within the xy plane for test case 2 and from below the xy plane for test cases 3 and 4. Bottom: intensity map of test case 1 as seen from the observer.