# interppolygon

Version 1.0.0.0 (2.25 KB) by
INTERPPOLYGON Interpolates a polygon.
Updated 11 Feb 2009

Y = INTERPPOLYGON(X,N) interporpolates a polygon whose coordinates are given in X over N points, and returns it in Y.

The polygon X can be of any dimension (2D, 3D, ...), and coordinates are expected to be along columns. For instance, if X is 10x2 matrix (2D polygon of 10 points), then Y = INTERPPOLYGON(X,50) will return a 50x2 matrix.

INTERPPOLYGON uses interp1 for interpolation. The interpolation method can be specified as 3rd argument, as in Y=INTERPPOLYGON(X,N,'method'). Allowed methods are 'nearest', 'linear', 'spline' (the default), 'pchip', 'cubic' (see interp1).

ALGORITHM
The point to point distance array is used to build a metric, which will be interpolated by interp1 over the given number of points. Interpolated points are thus equally spaced only in the linear case, not in other cases where interpolated points do not lie on the initial polygon. If this is an issue, try caalling INTERPPOLYGON twice, as in:
>> Y = INTERPPOLYGON(X,50); % Make a spline interpolation%
>> Z = INTERPPOLYGON(Y,50); % Will correct for uneven space between points

OUTPUT
On top of the interpolated polygon, [Y M] = INTERPPOLYGON(X,N) will return in M the metric of the original polygon.

EXAMPLE
X = rand(5,2);
Y = interppolygon(X,50);
figure, hold on
plot(X(:,1),X(:,2),'ko-')
plot(Y(:,1),Y(:,2),'r.-')

### Cite As

Jean-Yves Tinevez (2024). interppolygon (https://www.mathworks.com/matlabcentral/fileexchange/22948-interppolygon), MATLAB Central File Exchange. Retrieved .

##### MATLAB Release Compatibility
Created with R2008a
Compatible with any release
##### Platform Compatibility
Windows macOS Linux
##### Categories
Find more on Interpolation in Help Center and MATLAB Answers
##### Acknowledgements

Inspired: pencilROI

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!
Version Published Release Notes
1.0.0.0