So I've been using the dynamic lighting feature for many years now and this is something I haven't seen answered. Normally to create an obstruction, I draw lines and shapes in the DL layer with the drawing tool and the software maps out the rays of light and shadow accordingly. Also I know that I can upload images to other layers in the gamespace and then copy them to the DL layer and they don't behave as objects I create in the DL layer with the drawing tool. So my question is this, how does Roll20 know the difference? Or more specifically could I create similar line drawings in GIMP for example, save them as GIF or PNG files with a transparent component upload them into the object, GM or map layers then copy them to the DL layer have then work as shadow casting obstructions?