<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><div dir="ltr">Answer from Martin Davis<div><a href="https://www.linkedin.com/in/mrmartindavis/?originalSubdomain=ca">https://www.linkedin.com/in/mrmartindavis/?originalSubdomain=ca</a><br></div><div><a href="https://github.com/dr-jts">https://github.com/dr-jts</a><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">---------- Forwarded message ---------<br>From: <strong class="gmail_sendername" dir="auto">PostGIS</strong> <span dir="auto"><<a href="mailto:trac@osgeo.org">trac@osgeo.org</a>></span><br>Date: Thu, Sep 16, 2021 at 10:48 PM<br>Subject: Re: [PostGIS] #4992: Problem with ST_FrechetDistance in PostGIS/GEOS ?<br>To: <br>Cc: <<a href="mailto:postgis-tickets@lists.osgeo.org">postgis-tickets@lists.osgeo.org</a>><br></div><br><br>#4992: Problem with ST_FrechetDistance in PostGIS/GEOS ?<br>
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Reporter: ezimanyi | Owner: pramsey<br>
Type: defect | Status: new<br>
Priority: medium | Milestone: PostGIS 3.1.5<br>
Component: postgis | Version: 2.5.x<br>
Resolution: | Keywords:<br>
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<br>
Comment (by mdavis):<br>
<br>
Perhaps you have a more "batteries include" implementation of Frechet<br>
Distance.<br>
<br>
The PostGIS algorithm (coming from GEOS) is a Discrete Frechet Distance<br>
implementation. It works better if the geometry is densified via the<br>
optional third argument:<br>
<br>
{{{<br>
SELECT ST_FrechetDistance(<br>
'Linestring(1 1,2 2,3 1)',<br>
'Linestring(1 4,2 3,3 4,4 3)', .01);<br>
st_frechetdistance<br>
--------------------<br>
2.9800000000000004<br>
}}}<br>
<br>
-- <br>
Ticket URL: <<a href="https://trac.osgeo.org/postgis/ticket/4992#comment:1" rel="noreferrer" target="_blank">https://trac.osgeo.org/postgis/ticket/4992#comment:1</a>><br>
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