How to Establish Correspondences

Compute corners (typically 200-300 per image):

Correspondences are computed automatically and robustly in three stages:

1. Unguided matching: obtain a small number of seed matches using a local search and normalised cross-correlation with a conservative threshold.
   

2. Compute epipolar geometry: use seed matches to robustly compute (using RANSAC).
   Matches consistent with

3. Guided matching: Search for matches is then restricted to a band about epipolar lines using the computed .
   

Typically: number of corners in a image is about 300
number of seed matches is about 50-100
final number of matches is about 200-250
distance of a point from its epipolar line is 0.2pixels (using corners computed to sub-pixel accuracy).