<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"><span>Hi all,</span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; color: rgb(0, 0, 0); background-color: transparent; font-style: normal;"><span><br></span></div><div style="background-color: transparent;"><span>Thanks for your suggestions,</span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; color: rgb(0, 0, 0); background-color: transparent; font-style: normal;"><span><br></span></div><div style="background-color: transparent;"><span>What I really need is a polygon that have </span>exactly the same geometric center (centroid) of the original polygon. I donīt know If generalization algorithms (like st_simplify) have this
property. Same for st_segmentize. I need to make some tests first.</div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"><br></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; color: rgb(0, 0, 0); background-color: transparent; font-style: normal;">strk,</div><div style="background-color: transparent;">The use case is precisely calculating the polygonīs centroid by averaging the coordinates of all the points of the polygon. In order to perform this I think I need to have equally spaced points. Note that Iīm working on the ellipsoid so st_centroid no good to me...and I donīt want to project coordinates. </div><div style="background-color: transparent;"><br></div><div style="background-color: transparent; color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new york', times, serif; font-style: normal;">Thanks</div><div
style="background-color: transparent; color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new york', times, serif; font-style: normal;"><br></div><div style="background-color: transparent; color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new york', times, serif; font-style: normal;"><br></div><div style="background-color: transparent; color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new york', times, serif; font-style: normal;">Luis Tavares</div> <div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"> <div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"> <div dir="ltr"> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Sandro Santilli <strk@keybit.net><br> <b><span style="font-weight: bold;">To:</span></b> Luis Tavares <lmikegeo@yahoo.com>; PostGIS Users Discussion
<postgis-users@lists.osgeo.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, March 12, 2013 8:50 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [postgis-users] polygon with equally spaced points from an existing polygon<br> </font> </div> <br>
On Mon, Mar 11, 2013 at 09:22:09PM -0700, Luis Tavares wrote:<br><br>> How do I create a polygon with equally spaced points from an existing polygon?<br><br>Looks like a two steps process:<br><br> 1) drop vertices that are too close (st_simplify may help)<br> 2) add vertices where missing (st_simplify)<br><br>> I know that more the curvature or concavity changes sign more points are needed. So one solution would be to calculate the minimum of all distances between two consecutive points in the original polygon and use that distance to build my polygon with equally spaced points. Is this correct? If so, How do I proceed from here? Any ready made solution?<br><br>Calculating the minimum of all distances between two consecutive<br>points could be a useful standalone function. Don't you also need<br>minimum distance between any two points ? I'm curious about the<br>use case for the "consecutive only" approach.<br><br>--strk;<br><br><br>
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