Question about bbox transition

[imabackstabber]

In demo_fit.py, code below puzzles me:

bbox_info[:, :2] = bbox_info[:, :2] / focal_length.unsqueeze(-1) * 2.8  # [-1, 1]
bbox_info[:, 2] = (bbox_info[:, 2] - 0.24 * focal_length) / (0.06 * focal_length)  # [-1, 1]

what's the use of those magical number like 2.8, 0.24,0.06? I'll be more that appreciated if you can help me.