Is there a way of rendering an asset as invisible to the camera but visible to the bproc.writer.write_coco_annotations?

[lolitsjoey]

Describe your feature request

I have an asset that I want to get the bounding box for but I want it to be invisible for the camera/shadows/etc. everything else?

I know I can get round this by rendering twice, once with the asset visible and once with it not, but I have thousands of frames that I only render for 1 sample each anyway (quality is not a focus) so this is effectively doubling my render time.

Cheers for any thoughts?

Describe a possible solution

No response

[cornerfarmer]

Hey @lolitsjoey,

sorry for the late response. You could perform some kind of raycasts and check which rays hit the object, similar to https://github.com/DLR-RM/BlenderProc/blob/main/blenderproc/python/camera/CameraValidation.py#L158. With that information you could calculate the bounding box.
Alternatively, you could also sample points on the object surface and project it into the camera plane via bproc.camera.project_points. However, this will not consider for the object being hidden behind other objects.