BD TOPO® Extractor - Documentation

What’s the point

This tool allows you to extract specific data from IGN’s BD TOPO®. The extraction is based on either an extent drawned by the user on the map canvas or a layer’s extent. The data is based on the WFS service published by IGN with the Géoplateforme.

How to use it

Only 4 steps are required to use the BD TOPO® Extractor :

  1. Select the extent you want to use to extract data.

  2. Select the data you want to extract.

  3. Select if you want to clip the data based on the extent or keep all the features intersecting the extent intact.

  4. Select if you want to save the result or not, and if so the output folder and output format.

User Interface

user_interface

1. Select an extent

You can either draw a rectangle on the map (default) or select a layer in your project and use it’s extent.

Choose your weapon

2 checkboxes allow you to select how you want to get the extent used for the data extraction :

  • Draw an extent to extract data : if you want to use a drawned extent. Then you have to click the Draw an extent button and create a rectangle on the map.

  • Use a layer to extract data : if you want to use a layer’s extent or a layer’ boundary. Check it and then use the combobox to select the layer you want to use.

Error messages

The selected layer or the drawned rectangle is outside of the total extent of the WFS data.

outside_wfs_error

You can use the checkbox Draw the max extent of the WFS on the map to add a layer in your project to show the extent of the WFS.

The drawned rectangle or the selected layer is too big, the process can take a long time.

extent_too_big_error

2. Select data to export

All data in the WFS are listed in the middle part of the UI. You can either select all of the data with the checkbox Extract all data from BD TOPO® or select only the wanted data by checking their respectives checkboxes.

3. Select output geometry

You can extract all features intersecting the extent (default) by checking Intersecting the extent or choose to clip all features with the extent by checking within the extent. Finally if you choose to use a layer to extract data, you can clip all features within the layer by cheching within the layer.

4. Select output format

Save result as temporary layer

If you don’t want to save the extracted data as layers (default) you only have to select the output crs with the combobox. If the output format is a WFS, the CRS is automatically 4326 - WGS 84, it’s the crs of the source WFS.

Save result as layer

If you want to save the extracted data as layers you have to :

  • select the output crs with the combobox.

  • check the Save the results checkbox.

  • select if you want to add the exported data to the project (default) or not.

  • select the output format, GeoPackage, Shapefile or GeoJSon.

  • select the output folder to save the new layers inside a folder called BDTopoExport_yyyymmdd_HHMM.

If GeoPackage format is selected, only one file is created inside the folder with all layers inside.

If you don’t want to save the result, the output format is by default :

  • WFS if the user selected to only keep the data intersecting the extent.

  • GeoPackage (as memory layer) if the user selected to keep the data within the extent.

  • GeoPackage (as memory layer) if the user selected to keep the data within the layer.

Launch the extraction

The extraction begin when you press the OK button.

Additional tools

By clicking the IGN button, you’ll be redirected to IGN’s website. By clicking the Documentation button, you’ll be redirected to this page. By clicking the Metadata button, you’ll be redirected to the description of the BD TOPO® by IGN. A Plan IGN V2 basemap is automatically added to the project if there is no layer in it. So the user can draw a rectangle.