Surface Normal Estimation procedure

[Coderbitxh]

Hi,
I am performing zero-shot testing for surface normal estimation on KITTI dataset using your iDisc module. In order to understand the results better, I would like to understand how iDisc computes surface normals and what ground truth data does it use for surface normal estimation. Since I could not find much information through the paper, can you please tell me where to look for this information or perhaps give an answer here.

Thanks in advance