.. _lizmap-config-baselayers: Base layers =========== .. contents:: :depth: 3 Principle --------- It is often useful to separate base layers as a reference and thematic layers in a Web map. In Lizmap, you can use groups or layers as base layers. It is also possible to use external services in the Web map. The base layers are not part of the legend and are presented as a list. .. note:: If a single base layer is configured (project layer, external service or empty base layer), then Lizmap Web Client interface does not show the box *Base layers*, but the layer will be however visible below the other layers. Configuring the tool -------------------- The :guilabel:`Base layers` tab lets you add external services as base layer and an empty base layer. The empty base layer will display thematic layers over the project background color. .. image:: /images/interface-baselayers-tab.jpg :align: center :width: 80% The available base layers ------------------------- * *OpenStreetMap*, mapping project under free and open licenses: * OSM Mapnik: service available on openstreetmap.org * OSM stamen toner * OpenTopoMap * *ThunderForest*, **API key required**: * Open Cycle Map: OpenStreetMap cycling data including altitude information * *Google*, **API key required**: * Streets: the default Google Maps background layer * Satellite: the background map incorporating aerial and satellite images * Hybrid: the background map mixing streets and satellite * Terrain * *Bing Map*, **API key required**: * Streets: the default Bing Map background layer * Satellite: the background map incorporating aerial and satellite images * Hybrid: the background map mixing streets and satellite * *IGN Géoportail*, **API key required** for one layer: * Plan: The IGN rendering for the Web * Satellite: the background map incorporating IGN aerial and satellite images * Scan: the background map mixing the various IGN scan, API key needed * Cadastre The licenses are available at the following URLs: * *OpenStreetMap*: https://operations.osmfoundation.org/policies/tiles/ * *Google*: https://cloud.google.com/maps-platform/terms/ * *Bing*: https://www.microsoft.com/en-us/maps/product * *IGN*: https://geoservices.ign.fr/catalogue Scale with external base layer ------------------------------ All these external base layer are provided only in **EPSG:3857 / Pseudo Mercator** from the provider. The scale of such layer are **fixed** by the projection EPSG:3857. .. warning:: As a result, if you choose an external base layer, the project **will be displayed** in Google Mercator EPSG:3857. Therefore, if you have specified multiple scales in the Lizmap configuration, these intermediate scales **won't** be used. **Only** the **minimum** and **maximum** scale are used in this case. Read below about approximate scales. .. image:: /images/interface-scale-3857.jpg :align: center :width: 80% QGIS Server will perform **on the fly reprojection** for your data. It is therefore necessary to prepare the QGIS project accordingly. The *Google Mercator* coordinate reference system must be added in the Web Services CRSs list with the :menuselection:`Project properties --> QGIS Server --> WMS`. This is a list of a **very approximate** integer scale for a given zoom level for the **EPSG:3857**:: 0 500 000 000 1 250 000 000 2 150 000 000 3 70 000 000 4 35 000 000 5 15 000 000 6 10 000 000 7 4 000 000 8 2 000 000 9 1 000 000 10 500 000 11 250 000 12 150 000 13 70 000 14 35 000 15 15 000 16 8 000 17 4 000 18 2 000 19 1 000 20 500 .. warning:: These scales are just a hint of the scale. It is not possible to have rounded scale like this with EPSG:3857. Visit the OpenStreetMap website at the country level and check how the scale is changing while panning/zooming. https://www.openstreetmap.org/#map=6/48.995/4.856 External Lizmap layers ---------------------- This feature has been removed. It's replaced by the possibility of using the menu :menuselection:`Layer --> Embed Layers and Groups`, and in the plugin *Layers* tab declare the parent project and the Lizmap repository for the embed layers and groups. See :ref:`lizmap-cache-centralized`