Just globs, but they are pretty globs. Line at top of di is on mine too. Beam is so narrow, it can't recognize anything that shallow anyway. I fish shallow water, so I rarely see arches and don't look for them anymore.
Overlay allows you to put di image on top of 2d. This refines the blobs. Your 2d/di-si transducers must be within 6 inches of one another and you can only run 2d scroll speed on "normal" for overlay to work.

