[vtkusers] Using vtkProbeFilter to sample values of NIFTI volume onto surface

Sujin Philip sujin.philip at kitware.com
Mon Feb 25 09:24:19 EST 2019

Hi Michael,

In this case, for each vertex in the surface mesh, the filter finds the
voxel within which the vertex falls and interpolates the points values of
the 8 points of the voxel on to the vertex. The tolerance is used for
dealing with floating point errors. It specifies the tolerance to use when
a vertex is near the boundary of a cell to determine if it should be
considered to be inside the cell.


On Sat, Feb 23, 2019 at 6:59 PM Michael Jordan <mjordan080013 at gmail.com>

> Hi,
> i have a fMRI NIFTI volume whereby each voxel value corresponds to a
> statistical value indicating the activation. I am using the vtkProbeFilter
> to show the activation on the
> corresponding brain surface. The results looks pretty good but I would
> like to understand what is really going on when using the vtkProbeFilter.
> Assumed that I specify a tolerance value of 10.0 <+49100>, how the filter
> determines the corresponding scalar value for a certain surface vertex?
> Is the filter simply assigning the value of the closest voxel to the
> vertex? Or is the filter averaging all values within the specified
> tolerance?
> Thank you!
> Regards, Michael
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