I've been working on a Blender model (using Blender 2.79, but I've also tested in 2.91.2 and got the same result) with the goal of producing a realistic shadow image for an airplane from any angle. I'm using Cycles render engine, have imported my airplane model, and have a ground plane marked as a shadow catcher. I'm also using a Sun lamp with size 0 because I want crisp shadow edges. My lamp and camera need to be at the exact same location to generate the kind of shadow image I'm looking for.
My issue is that when I try to generate a shadow from a low elevation/grazing angle (around 30 degrees) I expect to see a long, stretched-out shadow on my shadow catcher. However, in reality I only see the shadow in places directly blocked by the airplane, meaning if I layer the outline of the airplane over the shadow image they are identical.
Does anyone know of settings I can change to get more realistic looking shadows?
Thank you so much for any help!