Cesium for backgrounds questions

I was exploring using Cesium for 3D backgrounds for animations. Think like making a movie, but with animated characters. E.g. a virtual travel guide showing popular tourist locations (anywhere good quality locations are available in Cesium). I was wondering how feasible / sensible an approach it would be.

Specific Questions:

  • Can I get a light weight 3D model of a location, say gltf, for previewing in a web browser (not final render). The rest of my app uses three.js - characters with animation, props, etc. The goal is to position characters and characters in a scene without the full overhead of a final render. I know there is CesiumJS, but I was not sure how easy to combine with three.js for the rest of the scene (the characters, props, etc).

  • I would then be after a high res version for final rendering in Omniverse/Unreal Engine etc. Want the distant view of locations (e.g. looking out of a building window into the distance). So again, I want to mix my generated content (my app exports the characters and animation clips in OpenUSD for rendering) into a world with Cesium filling out the background.

I want to move the camera around, so want 3D depth. I was not sure how to mix Cesium with both three.js (preview/editing) and a rendering platform (Omniverse/Unreal Engine/Unity) so I can have my 3D objects in the scene with Cesium for creating the background.

Any advice on whether this is a fruitful path to explore or not appreciated!