Fig. 2
From: Quality visual landmark selection based on distinctiveness and repeatability
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40648-015-0036-9/MediaObjects/40648_2015_36_Fig2_HTML.gif)
Positional relationship between feature point and reference point. Using direction and scale information of SIFT features extracted in a training image, the position of a reference point is estimated in an input image