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<style> BODY { font-family:Arial, Helvetica, sans-serif;font-size:12px; }</style>Hi Daniel,<br>
<br>
<span class="swb"></span>So if I undestand correctly you want to display you points and the colour the areas around them according to the nearest point (1), or if possible make a continous interpolated map that shows the gradients (2)?<br>
<br>
OK, this is not in the MapServer-topic, because MapServer has no way to do this. So I suggest we move this conversation private, but I'll try to give you an answer for future reference. If you have any questions, mail me directly.<br>
<br>
If this is indeed as you say non-dynamic, things are easy; with any respectable GIS package, you can create option (1) by making a Voronoi diagram. This makes polygons around yout points in which every location in its interior of the polygon is closer to its center point than it is to other points. The result is a vector image (shapefile).<br>
<br>
To create option (2) you have to interpolate these points into a (continuous) raster through any interpolation method. Simplest is nearest neighbour which in essence creates a Voronoi Diagram in raster format. If you want to go more pro, there is Inverse Distance Weighted (which I do not encourage people using because the options have huge influence on the outcome and are note really exact). Then there is Kriging, but you need to be into statistics quite a bit to be able to get a good outcome -- if not, leave it alone. Then there is also Natural Neighbour interpolation, which uses a Voronoi Diagram as its basis, and is thus quite well suited for using points that are anisotropically distributed, and when kriging is not an option.<br>
<br>
If you do want these things programatically, there are a couple of python scripts I have that you could use for create Nearest Neighbour and Natural Neighbour interpolations. You will need to adjust those quite a bit.<br>
<br>
Tom<br>
<br>
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Date: Wed, 23 Feb 2011 04:56:43 -0800 (PST)<br>
From: Josh Jordan <<a href="mailto:outerspaceman81@yahoo.com">outerspaceman81@yahoo.com</a>><br>
Subject: Re: [mapserver-users] Heatmap / choropleth from points<br>
attributes<br>
To: Daniel Cole <<a href="mailto:daniel@southernsolutionsms.com">daniel@southernsolutionsms.com</a>><br>
Cc: <a href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
Message-ID: <<a href="mailto:428818.75172.qm@web111314.mail.gq1.yahoo.com">428818.75172.qm@web111314.mail.gq1.yahoo.com</a>><br>
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<br>
First, you have to turn your points into shapes, theres some algorithm that will turn points into polygons with borders midway between each point. <br>
CLASS<br>
If your CSV data isnt joined to the mapserver data, you have to calculate what shapes are in each bucket like this-<br>
CLASS<br>
--- On Tue, 2/22/11, Daniel Cole <<a href="mailto:daniel@southernsolutionsms.com">daniel@southernsolutionsms.com</a>> wrote:<br>
<br>
From: Daniel Cole <<a href="mailto:daniel@southernsolutionsms.com">daniel@southernsolutionsms.com</a>><br>
Subject: [mapserver-users] Heatmap / choropleth from points attributes<br>
To: <a href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
Date: Tuesday, February 22, 2011, 10:06 PM<br>
<br>
I am a new mapserver user and have spent countless hours over the last month reading, trying code, etc. before posting here for help. <br>
<br>
I found some python code that I thought might do the trick , but it seems lots of heat maps are based off of how many points exist in a certain area, and thats now what I am doing. <br>
<br>
My points contain numbers in the attributes, 5, 25, 92, 71, etc. <br>
<br>
Thanks,<br>
<br>
Daniel<br>
<br>
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