This question is for @gigastacey does the pixel 4 radar use a raster scan?. And how does that work with time of flight? IE does it 3D map the entire space above it?
It maps the entire space in rapid pulses and then tracks what changed. The ML used to determine gestures is only focused on changes in hand position, and the resolution isn’t too high at any one pulse. A great explainer can be found in section 4 of this paper http://www.ivanpoupyrev.com/wp-content/uploads/2017/01/siggraph_final.pdf