I'm trying to capture depth images with a RGBD camera, but all of the images have undetectable outlines around objects:
Is this expected from RGBD cameras or is mine a dud? It's an Astra Pro.
That's perfectly normal and expected. Most RGBD camera work by projecting a point pattern into the world and capturing it with an IR-camera.
Camera and projector are positioned some cm apart (called baseline) to make triangulation possible. So there is always the chance that some parts of the world cannot be seen by the camera even though the projector put some pattern on them (and vice versa).
The camera also needs to see a small patch of the pattern and at depth jumps, some part of the pattern is missing.