the boundary with the vertices dropped that carry no shape, Douglas-Peucker chain by chain; MATLAB’s grainBoundary.simplify

Syntax

gB = gB.simplify()

The pixel staircase straightened.

gB = gB.simplify(0.5)

A tolerance of 0.5 map units.

gB = gB.simplify(protect=vertexIds)

These vertices kept as well.

gB = gB.simplify(keepGrains=grains.id)

No grain of the list collapsed.

Description

A vertex is dropped when leaving it out moves the boundary by less than epsilon, so many vertices go along a straight run and none at a corner; on a pixel grid this turns a staircase into the straight line it approximates. The junctions, the ends of the chains, always stay, so which grains touch, and where, is unchanged; a closed chain keeps at least three vertices. The dropped vertices’ segments are merged as by reduce.

The default tolerance is the median segment length over sqrt(2): a staircase of spacing d never strays further than d / sqrt(2) from the line it approximates, the worst case being a boundary at 45 degree, so it removes the grid and nothing else.

Input

`gB`	grainBoundary

Keywords

keyword	default	description
`epsilon`	`None`	the tolerance in the units of the map, how far the boundary may move; 0 leaves the boundary as it is, by default the median segment length over sqrt(2)
`protect`	`None`	the ids of the vertices that must stay, on top of the junctions
`keepGrains`	`None`	the ids of the grains that must keep a polygon: a grain smaller than epsilon would lose all its vertices and is not coarsened at all; MATLAB does this for every grain, grain2d.simplifyBoundary passes all of them

Output

`gB`	grainBoundary, the simplified boundary

Citing this page. This page is part of the documentation of MTEX, a free and open source MATLAB toolbox for analyzing and modeling crystallographic textures. It was written by The MTEX Developers and is published at https://mtex-toolbox.github.io/grainBoundary.simplify_py.html. If you use MTEX, or reuse text or figures from this page, in your research, please cite

F. Bachmann, R. Hielscher, H. Schaeben: Texture Analysis with MTEX - Free and Open Source Software Toolbox, Solid State Phenomena 160 (2010), 63-68. 10.4028/www.scientific.net/SSP.160.63

BibTeX

@article{bachmann2010mtex,
  author  = {F. Bachmann and R. Hielscher and H. Schaeben},
  title   = {Texture Analysis with MTEX - Free and Open Source Software Toolbox},
  journal = {Solid State Phenomena},
  volume  = {160},
  pages   = {63-68},
  year    = {2010},
  doi     = {10.4028/www.scientific.net/SSP.160.63},
  url     = {https://doi.org/10.4028/www.scientific.net/SSP.160.63}
}

Other papers describing specific MTEX methods are listed under Publications — please cite the one that best fits your application. The MTEX source code is licensed under the GNU General Public License v2.0; the text and figures of this documentation are licensed under CC BY 4.0, which permits reuse — including by automated systems — provided The MTEX Developers and this page are credited.

grainBoundary.simplify

Syntax

Description

Input

Keywords

Output

See also