Reduce an atlas's vertex count

Drops vertices from region geometry while keeping its topology, so an atlas costs less to store and to draw.

Usage

atlas_simplify(atlas, keep = 0.05, labels = NULL, exclude = NULL)

Arguments

atlas

A ggseg_atlas object with 2D geometry.

keep

Proportion of vertices to retain, between 0 and 1. Lower is smaller and blockier; near 1 is an effective no-op.

labels, exclude

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

Value

The ggseg_atlas, in the representation it arrived in.

Details

This is about size, not shape. The silhouette an atlas draws behind its structures usually carries the bulk of the vertices, so it is the part worth simplifying; tiny deep structures have few to spare. Use labels or exclude to say which.

See also

atlas_smooth() to round shapes off, and atlas_dilate() to grow or shrink them. Simplify first and smooth afterwards, so the smoothing has the last word on the outline.

Other atlas geometry: atlas_dilate(), atlas_smooth()

Examples

if (FALSE) { # \dontrun{
# Halve the atlas, sparing the structures.
atlas <- atlas_simplify(my_atlas, keep = 0.5, labels = "^cortex")
} # }