Isocontour

Find ISO-contour geometry in a 2D image using marching-squares, and sort the contour objects
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Updated 22 Apr 2024

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This function ISOCONTOUR computes the isocontour geometry for a certain 2D image and isovalue. To Extract the isocontour geometry it uses Marching Squares and linear interpolation. Followed by sorting the contour geometry into separate contour-objects.
This function is the 2D equivalent of Isosurface extraction using Marching Cubes in 3D.
[Lines,Vertices,Objects]=isocontour(I,isovalue);
inputs,
I : An 2D image (grey-scale)
isovalue : The Iso-value of the contour
outputs,
Lines : An array describing all the Line-pieces of the isocontour
geomtery, with a N x 2 index list of vertices
Vertices : Vertices (Corners) of the lines M x 2 list of X,Y
coordinates
Objects : A 1 x K cell array with in every cell a list of indices
corresponding to one connect isocontour. If the isocontour
is closed then the last index value is equal to first index
value.

Cite As

Dirk-Jan Kroon (2024). Isocontour (https://www.mathworks.com/matlabcentral/fileexchange/30525-isocontour), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2010b
Compatible with any release
Platform Compatibility
Windows macOS Linux

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Version Published Release Notes
1.4.0.0

Speedup sorting in objects

1.3.0.0

Changed sorting into objects from an n^2 time complexity algorithm into an n time complexity algorithm

1.1.0.0

Line normals now always point to the inside of the object.

1.0.0.0