Map tile sources

You can easily add or remove tile sources from the layer tab. It can be public tile sources or you can even generate your own tiles !

Edit tile sources

You need to copy tile_sources.xml in your user directory, and edit this file.

To do so, you can start PprzGCS, then go to File->Open user directory and File->Open app directory. Then just copy tile_sources.xml from the app directory to the user directory.

Note

The files in the user directory take precedence over those in the app directory.

A tile source is identified by an xml node of this form:

<source
    name="OpenStreetMap" dir="OSM_CLASSIC"
    addr="http://tile.openstreetmap.org/{z}/{x}/{y}.png"
    zoomMin="0" zoomMax="19"
    tileSize="256"
    format=".png"
/>

  • name is the name of the layer in PprzGCS.

  • dir is the name of the directory in which the tiles will be saved. In this example, the tiles are saved in map/OSM_CLASSIC.

  • addr is the address from which the tiles will be fetched.

    • Use {x}, {y} and {z} as placeholders for tiles coordinates.

    • Don’t forget to escape characters according to XML format (e.g. & become &amp;).

    • Set addr="" if don’t want to fetch tiles from internet but only from local directory.

  • zoomMin and zoomMax define the min and max available zoom levels.

  • tileSize is the size in pixel of the tiles. A current size is 256.

  • format is the file extension of the tiles. A current format is .png.

When you add a tile source, you also have to add a thumbnail for this source in pictures/map_thumbnails/<name>.png. The thumbnail should be a 200x100 pixels png.

Note

These directories will probably not exist the first time you add a layer, just create them !

Make your own tiles

You can make your own tiles with QGIS using the processing tool Raster tools -> Generate XYZ tiles (Directory).

Lets do a rather complicated example: I want to make a map for local ENU/NED coordinates from an image.

First, let create a georeferenced image:

  • In QGIS, go to Project->Properties->SRC and select the CRS in which your coordinates are.

Note

In my case, I want them to be in my local coordinate system, so I first have to define my own CRS:

  • Exit the properties and go to Settings->Custom projections.

  • Add a projection with the Proj String format, and the following parameters: +proj=ortho +lat_0=43.564092 +lon_0=1.48292, replacing the origin coordinates.

  • Select the newly created CRS in you project properties.

  • Go to Plugins->Manage and Install Plugins and activate Georeferencer GDAL.

  • Open the Raster->Georeferencer tool, and open you image with Open raster.

  • Open the Transformation settings and set the Target CRS, and the Output raster.

  • Click on a point you know the coordinates, and enter the coordinates.

  • Repeat the previous step for multiple points.

  • Run Start Georeferencing. You’re done!

Now, lets create the tiles:

  • Import the georeferenced image you created back in QGIS.

  • Run the processing tool Raster tools -> Generate XYZ tiles (Directory)

  • Select the extent and the minimun and maximum zoom

  • Select the output directory

  • Run the tool

Now, lets import theses tiles in PprzGCS:

  • Open the PprzGCS user directory, and copy the tiles directory in map/<YOUR_MAP_NAME>

  • Add the source to the tile_sources.xml file, as described above.

  • You’re done ! Open PprzGCS and enjoy !