Finally figured out a work flow for using HDRIs and backplates… I think this is starting to look pretty real world. The key I discovered is to use the same image in your backplate as a ground plane with the “window” as a vector input. Make sure you have sufficient light to cast a good solid shadow. Tutorials tell you to use the ground plane as a “shadow catcher”, but I disagree. It still looks like your model is floating. I add a gradient alpha mask on the ground object to help it blend in with the backplate and it keeps the model planted on the ground.
