c# - What is cross check in computer vision? -

i looking @ api emgu , brutheforcematcher. if create bruteforcematcher(t)(distancetype) constructor, not cross check. however, not know cross check is, , doesn't seem mentioned in api. in terms of emgu , computer vision, cross check?

from c++ api documentation:

crosscheck – if false, default bfmatcher behavior when finds k nearest neighbors each query descriptor. if crosscheck==true, knnmatch() method k=1 return pairs (i,j) such i-th query descriptor j-th descriptor in matcher’s collection nearest , vice versa, i.e. bfmatcher return consistent pairs. such technique produces best results minimal number of outliers when there enough matches. alternative ratio test, used d. lowe in sift paper.

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edit:

from understood i'm quite sure can sum above saying that, if found closest match b feature a, tuple (a,b) considered consistent pair , therefore returned if a closest match feature b.

a 1d example:

-----a------b---c

in case though b best match a not vice versa. instead, (b,c) consistent pair

-----a--b-------c

here, on other hand, (a,b) better match , returned.

(the other approach loewe mentioned in documentation has been discussed on over here)