allow gradient of unstructured data to optionally skip outputting the gradient but allow other gradient quantities to be output
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
Change the vtkGradientFilter to change the way gradients are computed for structured grids such that no gradient array is created (i.e. the array with 3 times the components if the input array and same number of points). often times other gradient quantities like vorticity or Q criterion are desired instead and the full gradient array can take up a lot of memory. for unstructured grids and polydata it probably won't make much of a difference memory-wise since cell links are used and the full gradient array is calculated at the beginning in order make a one-pass algorithm for computing gradients. this shouldn't be needed for image data, rectilinear grids and structured grids. this option should also be exposed in PV.