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I have a point pattern (see below) in which I assume to find "significant" lines of points. However, I did not find any method that is integrated in a GIS or in R that searches for such line pattern in a spatial point pattern. There is one method that is implemented in the free software called PAST (http://folk.uio.no/ohammer/past) called point alignment.

the method is described in :

Hammer, Ø. (2009). New statistical methods for detecting point alignments. Computers & Geosciences, 35(3), 659-666.

beyond this method I am not aware of any tool that finds lines in point patterns. Any hints on possible tools, r-packages, etc. are most welcome.

Spatial pattern of individual plants

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can you expand on what you consider to be significant? just colinear? –  iant Sep 3 '13 at 8:44
good question. I am not sure how to describe "significant" here. "colinear" is a good word though. I mean I "see" many lines but are these points really lined up or not? and if so, how many lines are there? as Oyvind stated below, it depends on the search radius. –  Jens Sep 3 '13 at 17:55

2 Answers 2

This paper: Christophe & Ruas 2002, Detecting Building Alignments for Generalisation Purposes, ISPRS, Ottawa. describes an operational method for the detection of small surfaces (buildings) alignements - it should work even better with points! (this method is rather robust since it is used for the production of 1:25000 maps in France).

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dear julien, great I will try to implement this approach in a r-function. look's interesting. –  Jens Sep 3 '13 at 17:37

I'm the author of Past and that paper you refer to. From your plot it seems like you have used a too large search radius. Try to decrease the Radius value. Also, if you would like to detect more lines, increase the alpha value (significance level).

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Oh, wow, that´s a surprise. :) In the plot I just draw a line by hand in order to make my message more clear. increasing alpha indeed gives more lines and I found many patterns. however, when do I know that I found the optimal solution? and should alpha be more like 0,05 or 0,1? one more problem is that lines appear/disappear when switching the radius from small to large. should I just notify all significant lines at all radii? one last question: what´s next after lines are identified? display them in a GIS? thanks for your comment and PAST ! –  Jens Sep 3 '13 at 17:39

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