It is basic VFX trick: most 3D compositing pipelines commonly use it. I tried to replicate it step by step inside Unity quickly.
It has a lot of problems but can help to sketch scenes quickly. The technique can be used for cut scenes, intros and simple fake 3D backgrounds. It's just an experiment.
image author: Steven_J
- set Unity projector and assign your image as texture
- start scene reconstruction with basic geometry (planes)
- adjust projector to fit perspective
- add camera movement & effects (particles, lights, etc.)
The most important thing is to match the perspective and geometry, which could be tricky. For your first try choose an image which can help you a little. Image with nice and visible perspective edges, with tiles on a floor, etc. Avoid images with complicated foreground or many objects.
You can download my sample project at the end of this page. Open the scene and check the Projector configuration.
Created by Unity 2017 Beta 1. (unity package & project).