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The FreeSurfer default ras2vox_tkr matrix.

Source: R/volume.R
ras2vox_tkr.Rd

Applying this matrix to a FreeSurfer surface RAS coordinate (from a surface file like lh.white) will give you the voxel index (CRS) in a conformed FreeSurfer volume. The returned matrix is the inverse of the vox2ras_tkr matrix.

Usage

ras2vox_tkr()

Value

numeric 4x4 matrix, the FreeSurfer ras2vox_tkr matrix.

See also

Other surface and volume coordinates: vox2ras_tkr()

Examples

   # Compute the FreeSurfer CRS voxel index of surface RAS coordinate (0.0, 0.0, 0.0):
   ras2vox_tkr() %*% c(0, 0, 0, 1);
#>      [,1]
#> [1,]  128
#> [2,]  128
#> [3,]  128
#> [4,]    1
   # Show that the voxel at surface RAS corrds (0.0, 0.0, 0.0) is the one with CRS (128, 128, 128):
   ras2vox_tkr() %*% c(0.0, 0.0, 0.0, 1);
#>      [,1]
#> [1,]  128
#> [2,]  128
#> [3,]  128
#> [4,]    1