The purpose of this module is to reduce the amount of tractography data for more rapid visualization and/or analysis. Especially for high resolution diffusion MRI data, points may be spaced very closely along fiber tracts. While this is important for computation of the fiber tracts for best anatomical accuracy, it is not necessary for visualization or most quantitative analyses. For example, if points are spaced every .2 mm along a fiber tract, this will be much slower to visualize than a fiber tract with points spaced every 1mm. In general, point spacing for visualization can be similar to the voxel size of accompanying image data (for example 1mm or 2mm).
This module can remove excess points or fibers (polylines) from a tractography (vtkPolyData) object. It aims for an output point spacing requested by the user. For example if input point spacing is 0.4mm, and the user requests 1mm, the module will find the largest possible point spacing under 1mm, which will be .8mm. Therefore about half of the points will be removed (0.4mm spacing to 0.8mm spacing). The rest of the points will be preserved. Also, both endpoints of each fiber will be preserved.