[mapserver-users] WMS - Change color map of a DEM dynamically

[Stephen Woodbridge]

Here is a good explanation:

https://lists.osgeo.org/pipermail/gdal-dev/2014-May/039091.html

On 5/30/2017 8:09 PM, Stephen Woodbridge wrote:
> I don't use QGIS so maybe someone else has some idea how to do what you 
> want with that. I think I might try something along these lines:
> 
> Create a GDAL VRT file for each theme and add appropriate color tables 
> for them. You might need to write a script to generate the color ramps 
> as color table entries, but once you have them you should be good.
> 
> The VRT files can all reference the same DEM.tif file so you are only 
> create VRT file for the color tables.
> 
> Then create appropriate layers in the mapfile each referencing one of 
> the VRT files. Then the user can select the appropriate WMS layer from 
> the mapfile dor the styling they want.
> 
> -Steve W
> 
> On 5/30/2017 7:56 PM, Eduardo Kanegae wrote:
>> Hi,
>>
>> I'm running MapServer 7.0.5 with GDAL 2.2.0 (CentOS x64) and have a 
>> 6Gb DEM tiff(float32) with overviews. Currently I set up a color ramp 
>> in QGIS based on values/colors of some GRASS color tables such as 
>> ETOPO2, SRTM and Terrain.
>> Then in mapfile I used a color ramp (colorrange, datarange, rangeitem) 
>> coying colors and limit values from QGIS themes.
>>
>> I'd like to let users to dynamically change the WMS raster output 
>> using QGIS. Then, it could avoid to duplicating LAYERS declarations 
>> such as "dem_srtmtheme", "dem_etopo2theme" and so on.
>> Or this (such as SLD) will be possible only for 8bit rasters and vectors?
>>
>> thanks in advance.
>>
>> Here's the dump(gdalinfo) of my raster file:
>>
>> Driver: GTiff/GeoTIFF
>> Files: /myfile.tif
>>         /myfile.tif.ovr
>> Size is 45369, 38050
>> Coordinate System is:
>> PROJCS["SIRGAS 2000 / UTM zone 23S",
>>      GEOGCS["SIRGAS 2000",
>>          
>> DATUM["Sistema_de_Referencia_Geocentrico_para_las_AmericaS_2000",
>>              SPHEROID["GRS 1980",6378137,298.257222101,
>>                  AUTHORITY["EPSG","7019"]],
>>              TOWGS84[0,0,0,0,0,0,0],
>>              AUTHORITY["EPSG","6674"]],
>>          PRIMEM["Greenwich",0,
>>              AUTHORITY["EPSG","8901"]],
>>          UNIT["degree",0.0174532925199433,
>>              AUTHORITY["EPSG","9122"]],
>>          AUTHORITY["EPSG","4674"]],
>>      PROJECTION["Transverse_Mercator"],
>>      PARAMETER["latitude_of_origin",0],
>>      PARAMETER["central_meridian",-45],
>>      PARAMETER["scale_factor",0.9996],
>>      PARAMETER["false_easting",500000],
>>      PARAMETER["false_northing",10000000],
>>      UNIT["metre",1,
>>          AUTHORITY["EPSG","9001"]],
>>      AXIS["Easting",EAST],
>>      AXIS["Northing",NORTH],
>>      AUTHORITY["EPSG","31983"]]
>> Origin = (268724.500000000000000,7485552.500000000000000)
>> Pixel Size = (1.000000000000000,-1.000000000000000)
>> Metadata:
>>    AREA_OR_POINT=Area
>> Image Structure Metadata:
>>    INTERLEAVE=BAND
>> Corner Coordinates:
>> Upper Left  (  268724.500, 7485552.500) ( 47d15' 6.30"W, 22d43'17.44"S)
>> Lower Left  (  268724.500, 7447502.500) ( 47d15'26.74"W, 23d 3'53.89"S)
>> Upper Right (  314093.500, 7485552.500) ( 46d48'36.78"W, 22d43'37.63"S)
>> Lower Right (  314093.500, 7447502.500) ( 46d48'53.22"W, 23d 4'14.43"S)
>> Center      (  291409.000, 7466527.500) ( 47d 2' 0.78"W, 22d53'46.41"S)
>> Band 1 Block=45369x1 Type=Float32, ColorInterp=Gray
>>    NoData Value=-32768
>>    Overviews: 22685x19025, 11343x9513, 5672x4757, 2836x2379
>>
>>
>> Eduardo Patto Kanegae
>> http://www.webmapit.com.br | @webmapit
>>
>>
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>> https://lists.osgeo.org/mailman/listinfo/mapserver-users
>>
> 
> 
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