. Equidistant Reduction Method

The TAU deformation module also contains this method to reduce the number of base points. It tries to select the base points Xs spatial-evenly distributed from the point set Xinp. This is managed by iteratively finding the right minimal distance dmin to possible neighboring base points, to get as close as possible to the maximal number of desired base points ns, max. Neighbors with a distances less than dmin are rejected during this process. Due to performance issues, it is using an octree data structure to find the neighbors closer than dmin to a specified base point. Figure 4 sketches one iteration step of the algorithm.

The result is having evenly distributed base points. But choosing the base points like this does not take into account the deformation vectors Axinpii or interpolation errors.