[mapserver-users] Multi-Resolution Terrain Map File

[Brent Fraser]

Here's a more current link:
http://www.gdal.org/gdaldem.html

And you could look into the VRT format to see if can help with the nodata
problem.

>   You could use the OFFSITE value in the higher resolution layer.
> Basically in this scheme, mapserver would render each layer, and any
> place with an OFFSITE value would show the value from the layer under
> it.
>
>   A more basic problem is how do you want the elevation value to be
> rendered  to a visible image?  You could use GDAL to pre-process the
> SRTM DEMs (http://www.perrygeo.net/wordpress/?p=7), or use mapserver to
> classify the DEM values to colors on the fly.
>
> Best Regards,
> Brent Fraser
>
>> How do I construct a map file that can handle different resolutions of
>> terrain, with fallback to lower resolution when a no-value is found?  In
>> Google Earth Fusion, I can specify multiple terrain sources and tell it
>> which value(s) represent missing data, and it will then process the
>> terrain, checking for availability of each type of terrain, falling back
>> if there isn't any in a geographic area and falling back if there is
>> missing data.
>>
>> For simple fallback based on area coverage, I can use a map file like
>> the
>> one below (using 30 Arcsecond SRTM and 1 Arcsecond DTED).  Now, what
>> would
>> I need to do to have it use/interpolate data from the 30 Arcsecond
>> values
>> when there is a missing data/NODATA/hole in the DTED?  In the file
>> below,
>> gdaltindex has been used to generate the coverage shapefiles.
>>
>> The example below is a simple one, and it would be really helpful to be
>> able to have multiple terrain sources and a way to automatically fill
>> voids the same way that transparency works with raster image layers.
>> Specifying that terrain values are posts and not pixels would be good
>> too,
>> but lower priority.
>>
>> Xander
>>
>> MAP
>>   NAME "srtm"
>>   EXTENT -180 -90 180 90
>>   SIZE 512 512
>>   UNITS DD
>>   IMAGETYPE bil
>>
>>   PROJECTION
>>     "init=epsg:4326"
>>   END
>>
>>   OUTPUTFORMAT
>>     NAME "bil"
>>     DRIVER "GDAL/EHdr"
>>     MIMETYPE "image/bil"
>>     EXTENSION "bil"
>>     IMAGEMODE INT16
>>   END
>>
>>   OUTPUTFORMAT
>>     NAME "bil16"
>>     DRIVER "GDAL/EHdr"
>>     MIMETYPE "application/bil16"
>>     EXTENSION "bil"
>>     IMAGEMODE INT16
>>   END
>>
>>   OUTPUTFORMAT
>>     NAME "gtiff_16"
>>     DRIVER "GDAL/GTiff"
>>     MIMETYPE "image/tiff"
>>     EXTENSION "tif"
>>     IMAGEMODE INT16
>>   END
>>
>>   WEB
>>     IMAGEPATH "/tmp/"
>>     IMAGEURL "/tmp/"
>>     LOG "/tmp/srtm.err"
>>     METADATA
>>       wms_title "SRTM Terrain"
>>     END
>>   END
>>
>>   #
>>   # Coarse (30 ArcSecond) terrain.  There is worldwide coverage, so this
>>   # is good for areas uncovered by SRTM data, as well as for high
>>   # scale values.
>>   #
>>   LAYER
>>     NAME "srtm"
>>     TILEINDEX "SRTM30/bathmetry.shp"
>>     TYPE RASTER
>>     PROCESSING "RESAMPLE=BICUBIC"
>>     STATUS ON
>>
>>     METADATA
>>       "wms_title" "SRTM 30 ArcSecond Bathmetry"
>>       "wms_group_title" "srtm30"
>>       "wms_srs" "epsg:4326"
>>       "wms_style" "Default"
>>       "wms_extent" "-180 -90 180 90"
>>     END
>>
>>     MAXSCALEDENOM 1000000000
>>     MINSCALEDENOM         10
>>   END
>>
>>   #
>>   # Moderate resolution (1 ArcSecond) terrain.  Coverage is available
>> worldwide
>>   # for most land areas between latitudes -60 and +60.
>>   #
>>   LAYER
>>     NAME "srtm"
>>     TILEINDEX "srt2f_1/srt2f_1.shp"
>>     TYPE RASTER
>>     PROCESSING "RESAMPLE=BICUBIC"
>>     STATUS ON
>>
>>     METADATA
>>       "wms_title" "SRTM 1 ArcSecond Bathmetry"
>>       "wms_group_title" "srtm30"
>>       "wms_srs" "epsg:4326"
>>       "wms_style" "Default"
>>       "wms_extent" "-180 -60 180 60"
>>     END
>>
>>     MAXSCALEDENOM 1000000
>>   END
>>
>> END
>>
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>
>
>
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