Confused about the Equation 6. in paper

[Jordan-5i]

hey, i am confused about the x_m-x_n and y_m-y_n when they are equal to zero under special condition using faster rcnn object detector, because center coordinates may be same and results to log(0). How do solve this problem?

[simaoh]

@Jordan-5i You are absolutely right, about the corner case of two bounding boxes with the same center coordinates.

To cover that explicitly in equation 6, one should replace |x_m-x_n| by min(|x_m-x_n|, eps) for some small constant eps>0.
In our code we do that with eps=0.001*w, and analogous computation for the y coordinates.

Here is the part of the code where we address this with torch.clamp (and also provide for the degenerate case of w=0, or h=0).

object_relation_transformer/misc/utils.py

Lines 245 to 255 in f21674d

	w = (x_max - x_min) + 1.
	h = (y_max - y_min) + 1.
	#cx.view(1,-1) transposes the vector cx, and so dim(delta_x) = (dim(cx), dim(cx))
	delta_x = cx - cx.view(batch_size, 1, -1)
	delta_x = torch.clamp(torch.abs(delta_x / w), min=1e-3)
	delta_x = torch.log(delta_x)
	delta_y = cy - cy.view(batch_size, 1, -1)
	delta_y = torch.clamp(torch.abs(delta_y / h), min=1e-3)
	delta_y = torch.log(delta_y)