Grow or shrink an atlas's regions

Buffers region geometry outward, so structures too thin to read at plotting size survive. This is the post-creation counterpart of the snapshot-stage dilation the atlas pipelines used to apply: it works on the finished atlas, so a build does not have to be repeated to retune it.

Usage

atlas_dilate(atlas, amount, labels = NULL, exclude = NULL)

Arguments

atlas

A ggseg_atlas object with 2D geometry.

amount

Buffer distance in geometry units. Positive grows a region, negative shrinks it, 0 returns the atlas unchanged.

labels, exclude

Regex selecting which labels to dilate, or which to leave alone. Give at most one.

Value

The ggseg_atlas, in the representation it arrived in.

Details

amount is a distance in the atlas's own geometry units, not voxels or pixels. Start small and look: a value that reads well on one atlas will not transfer to another built on a different grid.

Dilate the structures, not the anatomical context. Grown by even a little, a grey brain silhouette closes its sulci and flattens into a blob, so pass exclude (or labels) to keep it out.

See also

atlas_smooth() and atlas_simplify(), the other post-creation geometry steps.

Other atlas geometry: atlas_simplify(), atlas_smooth()

Examples

if (FALSE) { # \dontrun{
# Grow the structures and leave the grey brain alone
atlas <- atlas_dilate(atlas, 0.5, exclude = "^cortex")
} # }