Interpret camera registration export

Hello,

together with an obj I export a csv file for the camera registration. My goal is to visualize the cameras together with the mesh in open3d.

Loading the mesh is simple and works without any problems. The cameras positions given by x,y, and alt are also correct when I display them in open3d. However, I am having some problem with the direction of the camera, which is given by pitch, roll and heading in the csv file. How do I have to interpret these values and can transform them into a corresponding direction vector?

Thanks for any help!