Online Help > AlpineQuest 2.x > Maps & Layers

Digital Elevation Model (DEM)


The application is able to download and store elevation values of remote locations and let you use them in various ways, even while being offline.

Those elevations come from various sources including the SRTMGL1(v3) database and are currently available between latitude 56°S and 60°N with a precision of 1 arc second.


How to activate the use of elevation values?


To activate the download and use of elevation values:

  • Click on the Maps menu and on Options ;
  • Check Download and use elevation data .

The application will download the elevation values around the displayed area and show the elevation of the screen center location together with its coordinates .

Be sure to have the screen center coordinates displayed.

elevations-activate.jpg


How to check the coverage of stored data?


You can visualize the coverage of stored elevation values by displaying the coverage layer:

  • Click on the Maps menu and on Available maps ;
  • Click on the top left menu icon to display the left drawer menu;
  • Select Elevation data in the left drawer menu;

elevations-coverage-1.jpg


  • Select the DEM storage visualization layer .

Stored areas will be displayed over the current map .

elevations-coverage-2.jpg


How to get elevation profiles of paths?


When manually drawing a path or automatically drawing a path along roads over an area with elevation values stored, you can get the elevation profile and gain of that path:

  • Click anywhere on the path and select its name ;
  • Select Details and check the Statistics part.

auto-routing-4.jpg


How to use its own DEM data files?


If you don't want to use DEM values automatically downloaded by the application, you can use your own files. As long as the application finds the elevation data it needs, nothing will be downloaded.

You must use DEM files in the .HGT format (either 1201 or 3601 values per lines), following the usual rules:

  • File names must follow the .HGT naming convention;
  • Files containing 1201×1201 values (3″) must have a size of 2,884,802 bytes;
  • Files containing 3601×3601 values (1″) must have a size of 25,934,402 bytes;

The files must be copied inside the sub-folder /cache/dem/ of the application folder (the same folder used by the application to store the downloaded elevation data).

If your own data doesn't cover a requested area, the application will automatically download the missing data in its own format which may interfere with your own data. You can completely turn off the automatic download of data using the user setting maps.features.elevations.auto_download=false.

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