GDALGrid: nearest neighbor interpolation method does not work with empty search radius

[dron]

Nearest neighbor interpolation method does not handle search radius equal to zero properly. The documentation states that radius==0.0 uses the whole point array to search nearest value, but it doesn't.

This problem was fixed in 1.5 branch with r13815 and in trunk with r13816.

[dron]

This problem has been fixed.

[dron]

The fix for this problem introduced one regression. dfNearestR distance should be a square of largest semi-axis length. Fixed in trunk with the r15579 and in 1.5 with the r15580.

[dron]

I just found a grave bug introduced by the previous fix. Under some circumstances (when the point array exactly corresponds to raster grid nodes and we are going through the array starting from that exactly corresponding point) the algorithm goes one step more than needed and returns the value in array which follows the correct one.

That should be fixed in trunk with r21129 and in 1.7 with r21131.

A number of appropriate tests were added with r21130.