[mapserver-users] elevation profile

[Stephen Woodbridge]

Oh, one more point I wanted to mention is that the new PostGIS raster 
code might let you load the NED2 data directly into the database and get 
the contour information via a SQL query.

But I have not try to do that yet.

-Steve W

On 4/26/2012 8:20 PM, Stephen Woodbridge wrote:
> On 4/26/2012 7:35 PM, Puneet Kishor wrote:
>> Any suggestions on how something like this could be implemented using
>> MapServer?
>>
>> http://viewer.nationalmap.gov/example/elevation_profile.html
>>
>>
>> My front-end is OpenLayers, and the backend data are from SRTM. I'd
>> like to click on the map and create a line, and get back the elevation
>> numbers for that line. I only want the elevation numbers as I can
>> optionally construct the profile via a variety of ways.
>>
>> I am assuming I could send a line WKT, but how would I query for the
>> values using MapServer?
>>
>> Fwiw,
>> http://dev.openlayers.org/sandbox/camptocamp/canvas/openlayers/examples/elevationCanvas.html
>> seems to use a canvas implementation that doesn't seem to be available
>> in my standard-issue OL 2.11. Calling
>> `this.layer.getPixelDataForViewPortPx` croaks with "not a function"
>> message. In any case, I don't really want the RGB values under the
>> mouse. I want the actual height values.
>>
>> Thanks in advance for any suggestions,
>
> Hi Puneet,
>
> I have done this in the past and there are a bunch of moving parts. Here
> is what I did.
>
> 1. got a copy of NED2 data for the US.
> 2. create a gdal .vrt file to pull all the files into a single virtual file
> 3. wrote a simple C fcgi program to take an x,y and get the elevation
> from the the NED2 data.
>
> http://imaptools.com:8080/cgi-bin/getElevation.fcgi?lat=32.662864999999996&lon=-86.880096999999992
>
>
> 4. I used pgRouting to compute a route and then took the route geometry
> and added sample point along the edges where needed, and hit the fcgi
> service to convert the points to elevations and then plotted the
> elevations against the their length along the line that the x,y
> represented.
>
> I also think I may have wrote an app where you could pass the route
> polyline to it an it would generate an image of the elevation plot.
>
> 5. Then wired it into the web page as an ajax call of as a image url
> that gets updated.
>
> -Steve W
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