Voxel distance from surface

The utility function get_vox_dist returns the distance from each voxel in some space to the nearest vertex on the given surface. This function is used for generating ROI masks, cortical masks, etc.

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import cortex
import matplotlib.pyplot as plt

# get distance to nearest point on the mid-cortical (fiducial) surface from each
# voxel in the functional space for subject 'S1' and the transform 'fullhead'
dist, argdist = cortex.get_vox_dist(subject='S1',
                                    xfmname='fullhead',
                                    surface='fiducial')

# dist contains the distance from each voxel to the nearest vertex
# dist.shape = (31, 100, 100) <-- the same size as the functional volume

# argdist contains the index of the nearest vertex to each voxel
# argdist.shape = (31, 100, 100) <-- the same size as the functional volume

# let's visualize the distance field using the mosaic function
cortex.mosaic(dist, cmap=plt.cm.plasma)
plt.colorbar(label='mm from surface')