Project plane to a surface

Project a two-dimensional plane (such as 'ECoG' grid) to a three-dimensional surface while preserving the order

Usage

project_plane(
  target,
  width,
  height,
  shape,
  initial_positions,
  translate_first = TRUE,
  diagnostic = FALSE
)

Arguments

target

target surface to be projected to, must be object that can be converted to 'mesh3d' ('rgl' surface), for example, 'fs.surface' (from 'freesurferformat' package) or 'ieegio_surface' from 'ieegio' package.

width, height

width and height of the plane in world space (for 'ECoG' grid, the unit is millimeter)

shape

vector of two integers: the first element is the number of vertices (or electrode contacts) along 'width' direction; the second element is the number of vertices along 'height' direction. The total number of vertices of the plane will be prod(shape). Notice

initial_positions

a shape[[1]] x shape[[2]] x 3 array or a n x 3 matrix, where n is prod(shape), the number of vertices indicating the initial vertex positions of the plane

translate_first

whether to translate the plane first if the plane center is far from the surface; default is FALSE; set to TRUE for a warm start

diagnostic

whether to plot diagnostic figures showing the morphing progress.

Value

The projected vertex locations, same order as initial_positions.

Examples

# Construct target surface

sphere <- vcg_sphere()
target <- structure(
  class = "mesh3d",
  list(
    vb = cbind(
      sphere$vb[1:3, ] - c(0.8, 0, 0),
      sphere$vb[1:3, ] + c(0.8, 0, 0)
    ),
    it = cbind(
      sphere$it[1:3, ],
      sphere$it[1:3, ] + ncol(sphere$vb)
    )
  )
)
n_surfverts <- ncol(target$vb)

plane <- plane_geometry(width = 3, height = 3, shape = c(30, 30))
plane$vb <- plane$vb[1:3, , drop = FALSE] + c(0, 0, 2)
n_contacts <- ncol(plane$vb)

# First plot
x <- t(cbind(target$vb, plane$vb))
colnames(x) <- c('x', 'y', 'z')
graphics::pairs(
  x = x, asp = 1,
  col = c(
    rep("black", n_surfverts),
    rep("green", n_contacts)
  ),
  pch = c(
    rep(46, n_surfverts),
    rep(20, n_contacts)
  )
)


projected <- project_plane(
  target = target, width = 3, height = 3, shape = c(30, 30),
  initial_positions = t(plane$vb),
  translate_first = TRUE, diagnostic = FALSE
)

y <- rbind(x, projected)
graphics::pairs(
  x = y, asp = 1,
  col = c(
    rep("black", ncol(target$vb)),
    rep("green", n_contacts),
    rep("red", n_contacts)
  ),
  pch = c(
    rep(46, n_surfverts),
    rep(1, n_contacts),
    rep(20, n_contacts)
  )
)