Estimating correspondence between arbitrarily selected points in two widely-separated views

When monitoring events on a building site using a system of multiple cameras, it is necessary to establish correspondences between the acquired imaging material. The basic problem when attempting this task is the establishment of any the correspondence between points located on uniform areas of the images (e.g. regions with uniform colour or texture). This paper presents a new robust approach for establishing any correspondence between arbitrarily selected points in two widely-baselined views, based on the ASIFT (affine scale-invariant feature transform) method, image segmentation, and local homography. This method, denoted as ASIFT-SH, consists of the following steps: (i) determination of initial corresponding points, (ii) grouping of initial corresponding points into subsets, (iii) calculation of local homographies for a particular subset of points, and (iv) determination of any correspondence between arbitrary points from a particular camera’s view by using a suitable local homography. The ASIFT-SH method, when compared to searching the area surrounding an epipolar line (EPI method), provides more accurate results, especially on surfaces with similar pixel intensities. The average error in our method it is in the order of a few pixels, whilst for the EPI method in the order of a few hundred pixels.