Filter descriptors for valid 3d points

[DanielPollithy]

Hi!

Thank you for making hfnet publicly available.

The following problem occurred when I tried to use r2d2 together with hfnet:
The number of descriptors loaded from file for a single image (5000) did not match the number of 3d points retrieved (e.g. 1113).
Therefore match_against_place failed in line 103.

Could it be, that the loaded descriptors ought to be filtered by the "valid" mask?

Kind regards
Daniel