search-box:

The search box must contain the expected optimum pattern position on the second image. It is defined by its centre, equal to zero in the absence of a priori knowledge, and its size in each direction and . An excessive value of this range does not change the result, but it increases the computation cost, and may lead to the appearance of false vectors(3.3) due to spurious covariance(3.2.3) maxima. If the search range is too small, the true maximum covariance(3.2.3) is missed and false vectors(3.3) are obtained . If the maximum is right on the edge of the search zone, the CIVx programme yields a flag vec_F=-2 (and puts the maximum covariance to 0).

After completion of CIV, you must check on the histogram of displacements along each coordinate that you did not cut large displacement values (the histogram must drop to 0 for the maximum accessible displacements or . This histogram is shown by uvmat .