[mapserver-users] Point query from Mapserver raster

[Scott]

If you're using postgres/postgis it's easy using the raster version of 
st_intersection. It returns lat/lon/value or more precisely 
geometry/value. See more here:

https://postgis.net/docs/RT_ST_Intersection.html

Then it's just WFS.


On 10/29/21 4:09 PM, Carl Godkin wrote:
> Hi,
> Now that I have my WMS and WCS servers working well (thanks, list!!), I 
> have one more thing I would like to figure out how to do.
> 
> I want to do point queries on [Lat,Lon] points for their elevation from 
> the terrain layer I have.
> 
> I have done some searching and come across various ideas such as Raster 
> Query (https://mapserver.org/input/raster.html#raster-query 
> <https://mapserver.org/input/raster.html#raster-query>) and a query 
> template  
> (https://gis.stackexchange.com/questions/167239/mapserver-raster-picking-elevation-data 
> <https://gis.stackexchange.com/questions/167239/mapserver-raster-picking-elevation-data>) 
> but haven't found enough information for either to implement it.
> 
> I came up with a solution that works fine, but might be considered as 
> going "All Around the Barn"   What works is to add an ASCII output 
> format to my map file that serves terrain like this:
> 
> OUTPUTFORMAT
> NAME XYZ
> DRIVER "GDAL/XYZ"
> MIMETYPE "text/plain"
> IMAGEMODE FLOAT32
> EXTENSION "txt"
> END
> 
> and then use GetCoverage on a small rectangle whose lower-left corner
> is the point whose elevation I want:
> 
> http://localhost:8080/wcs?SERVICE=WCS&VERSION=2.0.1&REQUEST=GetCoverage&coverageid=SRTM_3_arc-second_grid&format=XYZ&subset=Lat(42.948,42.958)&subset=Lon(-122.086,-122.076) 
> <http://localhost:8080/wcs?SERVICE=WCS&VERSION=2.0.1&REQUEST=GetCoverage&coverageid=SRTM_3_arc-second_grid&format=XYZ&subset=Lat(42.948,42.958)&subset=Lon(-122.086,-122.076)>
> 
> and then take the first line of the returned output file.
> 
> What would Mapserver best practice be for a problem like this?
> 
> Thanks very much,
> 
> carl
> 
> 
> 
> 
> 
> 
> 
> 
> 
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