Abstract
noindent This document describes two new classes that facilitate the use of the doxygen{BSplineDeformableTransform} in multiresolution registration algorithms. The first class, doxygen{GridScheduleComputer}, defines the B-spline grid, based on a user-specified grid spacing and an input image (the fixed image in registration). A different grid is determined for each resolution level of the registration, given a multiresolution schedule similar to that of the image pyramids. The second class, doxygen{UpsampleBSplineParametersFilter}, resamples (usually upsamples) the B-spline coefficients to a new control point grid having a different spacing/origin/size. This can be used to transfer the result from one resolution level to that of the next level. Summarising, suitable grid definitions follow from the first class, and are used as input for the second class, which performs the actual resampling. The classes are implemented using the Insight Toolkit url{www.itk.org}. This paper is accompanied with the source code, including a test program.