fm_simplify {fmesher}

Recursive curve simplification.

Description

Simplifies polygonal curve segments by joining nearly co-linear segments.

Uses a variation of the binary splitting Ramer-Douglas-Peucker algorithm, with an ellipse of half-width eps ellipse instead of a rectangle, motivated by prediction ellipse for Brownian bridge.

Usage

fm_simplify(x, eps = NULL, eps_rel = NULL, ...)

Arguments

x

An fm_segm() object.

eps

Absolute straightness tolerance. Default NULL, no constraint.

eps_rel

Relative straightness tolerance. Default NULL, no constraint.

...

Currently unused.

Details

Variation of Ramer-Douglas-Peucker. Uses width epsilon ellipse instead of rectangle, motivated by prediction ellipse for Brownian bridge.

Value

The simplified fm_segm() object.

Author(s)

Finn Lindgren [e-mail]

References

Ramer, Urs (1972). "An iterative procedure for the polygonal approximation of plane curves". Computer Graphics and Image Processing. 1 (3): 244–256. doi:10.1016/S0146-664X(72)80017-0

Douglas, David; Peucker, Thomas (1973). "Algorithms for the reduction of the number of points required to represent a digitized line or its caricature". The Canadian Cartographer. 10 (2): 112–122. doi:10.3138/FM57-6770-U75U-7727

See Also

Other object creation and conversion: fm_as_fm(), fm_as_lattice_2d(), fm_as_mesh_1d(), fm_as_mesh_2d(), fm_as_segm(), fm_as_sfc(), fm_as_tensor(), fm_lattice_2d(), fm_mesh_1d(), fm_mesh_2d(), fm_segm(), fm_tensor()

Examples

theta <- seq(0, 2 * pi, length.out = 1000)
(segm <- fm_segm(cbind(cos(theta), sin(theta)),
  idx = seq_along(theta)
))
(segm1 <- fm_simplify(segm, eps_rel = 0.1))
(segm2 <- fm_simplify(segm, eps_rel = 0.2))
plot(segm)
lines(segm1, col = 2)
lines(segm2, col = 3)

(segm <- fm_segm(cbind(theta, sin(theta * 4)),
  idx = seq_along(theta)
))
(segm1 <- fm_simplify(segm, eps_rel = 0.1))
(segm2 <- fm_simplify(segm, eps_rel = 0.2))
plot(segm)
lines(segm1, col = 2)
lines(segm2, col = 3)