Resolve an anatomical underlay for a surface atlas

Uses an explicit metric, then the atlas anatomy metric, otherwise a metric computed from matching white geometry. Supplied metrics are used unchanged. The result can be shared by static and interactive renderers. No curvature is inferred from an inflated surface.

Usage

surface_anatomy(
  surfatlas,
  hemi = "lh",
  metric = NULL,
  source = NULL,
  type = c("curvature", "sulcal_depth")
)

Arguments

surfatlas

A surface atlas.

hemi

Hemisphere, lh or rh (left and right are also accepted).

metric

Optional finite per-vertex metric overriding the atlas.

source

Optional provenance label for the supplied metric.

type

Computed metric used when neither `metric` nor the atlas supplies one: `"curvature"` (default) or `"sulcal_depth"`.

Value

A list with metric and provenance. Unavailable computed anatomy is neutral, with source recorded as neutral_fallback.

Details

Two computed metrics are available. `"curvature"` is mean curvature of the white surface with five adjacency averaging steps; it resolves individual folds but looks mottled on inflated displays. `"sulcal_depth"` is a FreeSurfer-style sulcal-depth proxy, the signed displacement between the white and the displayed (inflated) surface from [neurosurf::surface_sulcal_proxy()]; it gives the broad two-tone gyral/sulcal pattern used by Workbench and pycortex. When the proxy cannot be computed (for example on a white display surface) curvature is used instead and the provenance records that.

Examples

if (FALSE) { # \dontrun{
atlas <- get_schaefer_surfatlas(100)
anatomy <- surface_anatomy(atlas, hemi = "lh")
} # }