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Fast Line Segment Intersection

4.9 | 11 ratings Rate this file 49 Downloads (last 30 days) File Size: 3.5 KB File ID: #27205 Version: 1.1
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Fast Line Segment Intersection


U. Murat Erdem (view profile)


08 Apr 2010 (Updated )

Finds the pairwise intersection points between line segments in 2D Cartesian space.

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OUT = LINESEGMENTINTERSECT(XY1,XY2) generates intersection analysis between the line segment sets given in XY1 and XY2. Code can handle coincident and parallel lines.

The main emphasis is on speed. The code is fully vectorized and it runs pretty fast (orders of magnitude) compared to some of the previous postings.


Fast And Robust Curve Intersections inspired this file.

This file inspired Segments Intersection Test Functions.

MATLAB release MATLAB 7.9 (R2009b)
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Comments and Ratings (12)
06 Jul 2016 Liwei Dai

Just checked your code, it seems that the entries in out.intMatrixX, out.intMatrixY are not correct. Many of the entries are filled with zeros which should be NaN if there is no intersection between two line segments, right?
Another thing is the link to the algorithm behind this just doesn't work anymore, could you please give me another link? I felt it's pretty awesome to learn this. :)

23 Jul 2015 M. F.

M. F. (view profile)

18 Nov 2014 Sam Murthy

Please consider changing the parallelism check to abs(denominator) < some small number. This will catch lines that are parallel to within some threshold.

08 Aug 2013 Matthew Bays

12 Jun 2013 Ulrik

Ulrik (view profile)

18 Mar 2012 Francesco Montorsi

I've found your function very useful, thanks! However I recently wanted to squeeze out some additional performance and ended up rewriting the thing in MEX C code, which can be compiled and run from MATLAB... I posted my code at .

03 Aug 2011 Brandon

16 Jun 2011 piet fue

07 Apr 2011 Maher HAMDI

05 Nov 2010 Alex

Alex (view profile)

Quick and effective. However, I believe there is a typo in the documentation:

'intNormalizedDistance2To1' : N1xN2 matrix where the (i,j) entry is the normalized distance from the start point of line segment XY1(j,:) to the intersection point with XY2(i,:).

This description is the same as intNormalizedDistance1To2 except that i and j are swapped in the description, and that doesn't really make any sense. I believe XY1 and XY2 should also be swapped.

Comment only
05 Nov 2010 Alex

Alex (view profile)

30 Apr 2010 Fabio Pinna

It worked fine and fast for me! Good work!
Good vectorization.
The complex output prevent further vectorization but it is already fast enough

10 Apr 2010 1.1

Changed the input parameters and the output structure. Now the analysis can be done between two sets of line segments. Analysis also provides more information about the intersections.

Please see the CHANGELOG in the comments.

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