R: Low level function for high-quality triangulations

inla.mesh.create {INLA}

R Documentation

Low level function for high-quality triangulations

Description

Create a constrained refined Delaunay triangulation (CRDT) for a set of spatial locations.

Usage

inla.mesh.create(
  loc = NULL,
  tv = NULL,
  boundary = NULL,
  interior = NULL,
  extend = (missing(tv) || is.null(tv)),
  refine = FALSE,
  lattice = NULL,
  globe = NULL,
  cutoff = 1e-12,
  plot.delay = NULL,
  data.dir,
  keep = (!missing(data.dir) && !is.null(data.dir)),
  timings = FALSE,
  quality.spec = NULL,
  crs = NULL
)

inla.delaunay(loc, ...)

Arguments

`loc`	Matrix of point locations. Can alternatively be a `SpatialPoints` or `SpatialPointsDataFrame` object.
`tv`	A triangle-vertex index matrix, specifying an existing triangulation.
`boundary`	A list of `inla.mesh.segment` objects, generated by `inla.mesh.segment()`, specifying boundary constraint segments.
`interior`	A list of `inla.mesh.segment` objects, generated by `inla.mesh.segment()`, specifying interior constraint segments.
`extend`	`logical` or `list` specifying whether to extend the data region, with parameters list("n") the number of edges in the extended boundary (default=8) list("offset") the extension distance. If negative, interpreted as a factor relative to the approximate data diameter (default=-0.10) Setting to `FALSE` is only useful in combination `lattice` or `boundary`.
`refine`	`logical` or `list` specifying whether to refine the triangulation, with parameters list("min.angle") the minimum allowed interior angle in any triangle. The algorithm is guaranteed to converge for `min.angle` at most 21 (default=`21`) list("max.edge") the maximum allowed edge length in any triangle. If negative, interpreted as a relative factor in an ad hoc formula depending on the data density (default=`Inf`) list("max.n.strict") the maximum number of vertices allowed, overriding `min.angle` and `max.edge` (default=-1, meaning no limit) list("max.n") the maximum number of vertices allowed, overriding `max.edge` only (default=-1, meaning no limit)
`lattice`	An `inla.mesh.lattice` object, generated by `inla.mesh.lattice()`, specifying points on a regular lattice.
`globe`	Subdivision resolution for a semi-regular spherical triangulation with equidistant points along equidistant latitude bands.
`cutoff`	The minimum allowed distance between points. Point at most as far apart as this are replaced by a single vertex prior to the mesh refinement step.
`plot.delay`	On Linux (and Mac if appropriate X11 libraries are installed), specifying a numeric value activates a rudimentary plotting system in the underlying `fmesher` program, showing the triangulation algorithm at work.
`data.dir`	Where to store the `fmesher` data files. Defaults to `tempdir()` if `keep` is `FALSE`, otherwise `"inla.mesh.data"`.
`keep`	`TRUE` if the data files should be kept in `data.dir` or deleted afterwards. Defaults to true if `data.dir` is specified, otherwise false. Warning: If `keep` is false, `data.dir` and its contents will be deleted (unless set to `tempdir()`).
`timings`	If `TRUE`, obtain timings for the mesh construction.
`quality.spec`	List of vectors of per vertex `max.edge` target specification for each location in `loc`, `boundary/interior` (`segm`), and `lattice`. Only used if refining the mesh.
`crs`	An optional `CRS` or `inla.CRS` object
`...`	Optional parameters passed on to `inla.mesh.create`.

Details

inla.mesh.create generates triangular meshes on subsets of R^2 and S^2. Use the higher level wrapper function inla.mesh.2d() for greater control over mesh resolution and coarser domain extensions.

inla.delaunay is a wrapper function for obtaining the convex hull of a point set and calling inla.mesh.create to generate the classical Delaunay tringulation.

Value

An inla.mesh object.

Author(s)

Finn Lindgren finn.lindgren@gmail.com

Examples


loc = matrix(runif(10*2),10,2)

mesh = inla.delaunay(loc)
plot(mesh)

mesh = inla.mesh.create(loc,
                        interior=inla.mesh.segment(idx=1:2),
                        extend=TRUE,
                        refine=list(max.edge=0.1))
plot(mesh)

loc2 = matrix(c(0,1,1,0, 0,0,1,1), 4, 2);
mesh2 = inla.mesh.create(loc=loc,
                         boundary=inla.mesh.segment(loc2),
                         interior=inla.mesh.segment(idx=1:2),
                         quality.spec=list(segm=0.2, loc=0.05),
                         refine=list(min.angle=26))
plot(mesh2)

[Package INLA version 20.11.29 Index]