How to calculate the rotation angle given the rotation matrix?

Question

Mathematics

Hello,
by the method of not cunning manipulations, I found a rotation matrix. In my case, the change between two point clouds, as described here. rwthmeditec.github.io/TRTK/html/class_t_r_t_k_1_1_...
As now from view matrix

[ 0.99, -0.0001, 0.01, -0.0366556;
0.0001, 1, -0.0004, 0.0035;
-0.011, 0.0004, 0.999, 0.02851;
0, 0, 0, 1]

calculate the angle of change.
Thank you very much!

Answer 1

https://stackoverflow.com/questions/40271959/how-t...
Only you don't have a rotation matrix: the last column (like the last row) should be (0; 0; 0; 1).
Don't forget to check if your strings are normalized.