Compute volume for manifold meshes
Coercing Surface Inputs
The surface objects are converted to 'mesh3d' object before
applying further calculations.
When surface is a surface ieegio object, the returned
mesh3d$vb contains vertices that have been left-multiplied by
surface$geometry$transforms[[1]] (the first transform stored in the
geometry, typically the ScannerAnat or voxel-to-world transform).
Breaking change: Earlier versions (before 0.2.6) of ravetools
returned the raw surface$geometry$vertices without applying any
transform, so downstream code often multiplied by
surface$geometry$transforms[[1]] (or an equivalent) manually before
working in world space. Such code will now double
apply the transform and produce incorrect coordinates. If you previously
applied a transform from surface$geometry$transforms by hand after
calling a ravetools mesh function on an 'ieegio_surface',
remove that manual step.
Surfaces with an empty or missing geometry$transforms list (for
example, surfaces produced by ieegio's volume_to_surface,
which stores an identity transform) are unaffected.
If geometry$transforms contains multiple transforms targeting
different coordinate spaces, only the first one is used. Callers that need
a specific target space should select and apply that transform themselves
before calling ravetools mesh functions.
Examples
# Initial mesh
mesh <- vcg_sphere()
vcg_mesh_volume(mesh)
#> [1] 4.152741