Digital Elevation Tools

c2cgeoportal applications include web services for getting DEM information. The raster web service allows getting information for points. The profile web service allows getting information for lines.

To configure these web services, you need to set the raster variable in the application config (vars.yaml). For example:

        file: /var/sig/altimetrie/mns.vrt
        type: gdal
        round: 1
        file: /var/sig/altimetrie/mnt.vrt
        type: gdal
        round: 1

raster is a list of “DEM layers”. There are only two entries in this example, but there could be more.

file provides the path to the shape index that references the raster files. The raster files should be in the Binary Terrain (BT/VTP .bt 1.3) format. One may use GDAL/OGR to convert data to such a format.

type shp_index (default) for Mapserver shape index, or gdal for all supported GDAL sources. We recommend to use a vrt file built with gdalbuildvrt.

nodata specifies the nodata value. By default the nodata value is directly read from the source.

round specifies how the result values should be rounded. For instance ‘1’: round to the unit, ‘0.01’: round to the hundredth, etc.


gdalbuildvrt usage example:

Set the environment variables (example for Exoscale):

export AWS_DEFAULT_REGION=ch-dk-2
export AWS_ACCESS_KEY_ID=<key>
export AWS_SECRET_ACCESS_KEY=<secret>

Get the list of uploaded files:

aws --endpoint-url --region ch-dk-2 s3 ls s3://<bucket>/<folder>

Create a file named e.g.: list.txt with the files we want to generate.


And finally generate the VRT file with:

gdalbuildvrt -input_file_list list.txt /vsis3/<bucket>/<folder>/<file>.vrt