About focal_scale

[DongyangHuLi]

Hi, thank you for nice work!
I'm confused about the 'focal_scale'. Why do we need to do this:

SurroundDepth/runer.py

Lines 382 to 383 in 22dfecf

	if self.opt.focal:
	pred_depth = pred_depth * data[("K", 0, 0)][i, 0, 0].item() / self.opt.focal_scale

[weiyithu]

Depth estimation results are related to focal length. Here we encode focal length information to the network by simply multiply a focal scale. For a more elegant method and the theoretical relation between focal length and depth, you may refer to this paper: Metric3D: Towards Zero-shot Metric 3D Prediction from A Single Image.