I’m trying to verify my Camera implementation (extrinsics + intrinsics) by comparing reverse-projections of matching 2D points in different frames, but it seems to be wrong.
Dataset: ICL-NUIM (synthetic), video lr-kt0 
The two frame used: 1 and 600
Point to match: bottom left corner of the wall frame:
- In frame 1 : x = 386, y = 278, depth = 16820 / 5000
- In frame 600: x = 14, y = 102, depth = 10670 / 5000
The camera extrinsics ground truth are given using the TUM format (translation, rotation in quaternion) .
I have implemented a Camera type using nalgebra . I’m using it in the example file . I was thinking that both back projections should give the same 3D point, but that’s not what I get.
Am I doing / assuming something fundamentally wrong, or did I make an implementation mistake? I am hoping some of you with more experience with nalgebra and projective geometry might know the answer.
 ICL-NUIM dataset: https://www.doc.ic.ac.uk/~ahanda/VaFRIC/iclnuim.html
 TUM dataset format: https://vision.in.tum.de/data/datasets/rgbd-dataset/file_formats
 My camera module: github mpizenberg/computer-vision-rs/blob/master/src/camera/mod.rs
 Short example: github mpizenberg/computer-vision-rs/blob/master/examples/camera.rs
Sorry for the github links, I have a new user restriction of two links.