How to obtain ground truth 2D point matches?

[ramdrop]

Hi, thanks for your excellent work. In the original paper you write:

3.4 Overall training objective (b) a smooth-L1 loss between the 2D points output after soft argmax and ground truth 2D point matches...

I am a bit confused by the term "ground truth 2D point matches". Are they obtained by transforming the 2D points in a reference image to a target image using the ground truth pose?