scale issue and normalized coords issue

[jeannotes]

hi, thanks for the great work.
and I have several questions:
1.
suppose my input img is (384,384), batch-size 20, window-size 5
when do fine matching with fine features(192, 192), you use torch's unfold with stride and padding to get feat_f0_unfold(20,3200,2304)
the in FineMatching you get heatmap and calculate nornalized_coords, I can understand this,
but when calculate "expec_f_gt", you use "w_pt0_i" "pt1_i", and it is calculated like this:
"expec_f_gt = (w_pt0_i[b_ids, i_ids] - pt1_i[b_ids, j_ids]) / scale / radius"
why devided by scale and radius? I debug inside scale is 2, radius is 2 also
the "expec_f_gt " seems not normalized, hope that you can explain.
2.
unlike dense matching ideas, this paper fisrt do coarse match and around those coarse do fine search, seems to be "2-step "algorithm, am I right?
3.
In coarsematching, you samples gt correspondence, does this affect accuracy? any experiments?