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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