bufferm2

Creates a buffer zone around or inside a polygon or polygons
3K Downloads
Updated 23 Sep 2021

bufferm2.m Documentation

Author: Kelly Kearney View bufferm2 on File Exchange

This function is mostly a legacy one. In early versions of the Mapping Toolbox (circa 2005 or so), the bufferm.m function included some buggy behavior, causing it to be very slow and occasionally fail completely. I wrote this function as a replacement.

The bugs were corrected in R2006b, but I kept this version around because it handled polygon holes more robustly than the original: bufferm simply filled them in, while bufferm2 trims or pads holes according to the buffer width.

Somewhere between R2006b and R2013a, the behavior of bufferm.m was updated to handle holes in the same way as my version. So now, really the only difference between the two is that mine can be applied in cartesian coordinates.

Syntax

[latb,lonb] = bufferm2(lat,lon,dist,direction)
[latb,lonb] = bufferm2(lat,lon,dist,direction,npts)
[latb,lonb] = bufferm2(lat,lon,dist,direction,npts,outputformat)
[xb,  yb]   = bufferm2('xy',x,y,dist,direction,npts,outputformat)

See function help for description of input and output variables.

Example

We'll use the Great Lakes polygons as our starting point.

load conus;

usamap({'MN','NY'});
geoshow(uslat, uslon, 'color', 'k');
geoshow(statelat, statelon, 'color', 'k');
geoshow(gtlakelat, gtlakelon,...
    'DisplayType', 'polygon', 'FaceColor', 'blue')

bufferm2_1

Calculate a 1-deg outward buffer. We use a reduced-point version of the polygon as our input, since most of the little features will be smoothed out by the buffering process anyway. The result of this calculation is the same as from the bufferm function.

tol = 0.1; 
[reducedlat, reducedlon] = reducem(gtlakelat, gtlakelon, tol);

dist = 1;
[latb, lonb] = bufferm2(reducedlat, reducedlon, dist, 'out');

geoshow(latb, lonb, 'DisplayType', 'polygon', 'FaceColor', 'yellow');
geoshow(gtlakelat, gtlakelon, 'color', 'b', 'linestyle', ':');

bufferm2_2

Cite As

Kelly Kearney (2024). bufferm2 (https://github.com/kakearney/bufferm2-pkg), GitHub. Retrieved .

MATLAB Release Compatibility
Created with R2007a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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bufferm2

Versions that use the GitHub default branch cannot be downloaded

Version Published Release Notes
1.4.0.1

linked GitHub readme

1.4.0.0

Linked to GitHub repository

1.3.0.0

Fixed a bug in input checks so input can be either row or column vectors. Also updates internal plot checks to plot in cartesian coordinates so can be used to check both geographic and x-y input.

1.1.0.0

Added ability to work in cartesian coordinates rather than geographic space; updated description and example on webpage.

1.0.0.0

Added link and comments to this web page regarding the updated version of bufferm.

To view or report issues in this GitHub add-on, visit the GitHub Repository.
To view or report issues in this GitHub add-on, visit the GitHub Repository.