PF is a great tool for UWB. Even without IMU data and instead adding uniform diffusion of the particles between updates tracking worked well in a 2D environment. It sounds like you're working on TDOA for UWB?

I've done something similar for a rowing machine. There is actually a bluetooth standard for fitness machines which was applicable in my situation.

https://www.bluetooth.com/specifications/specs/fitness-machi...

I believe the SIFT algorithm is most commonly used. Harris struggles when features change in scale between images, whereas SIFT does not. Harris can be outfitted with a Laplacian pyramid to overcome the scale issue though.

which is funny since SIFT is basically just as ancient.