# BD TOPO® Extractor - Documentation

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## 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](https://www.ign.fr/geoplateforme).

## 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.](https://julesgrillot.github.io/plugin_bd_topo_extractor/index.html#select-an-extent)

1. [Select the data you want to extract.](https://julesgrillot.github.io/plugin_bd_topo_extractor/index.html#select-data-to-export)

1. [Select if you want to clip the data based on the extent or keep all the features intersecting the extent intact.](https://julesgrillot.github.io/plugin_bd_topo_extractor/index.html#select-output-geometry)

1. [Select if you want to save the result or not, and if so the output folder and output format.](https://julesgrillot.github.io/plugin_bd_topo_extractor/index.html#select-output-format)

### User Interface

<p align="center">
  <img src="https://raw.githubusercontent.com/JulesGrillot/plugin_bd_topo_extractor/main/bd_topo_extractor/resources/images/plugin_ui.png?raw=true" alt="user_interface"/>
</p>

### 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 layer extent to extract data :` if you want to use a layer's extent. 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.

<p align="center">
  <img src="https://raw.githubusercontent.com/JulesGrillot/plugin_bd_topo_extractor/main/bd_topo_extractor/resources/images/outside_wfs_error.png?raw=true" alt="outside_wfs_error"/>
</p>

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

<p align="center">
  <img src="https://raw.githubusercontent.com/JulesGrillot/plugin_bd_topo_extractor/main/bd_topo_extractor/resources/images/extent_too_big_error.png?raw=true" alt="extent_too_big_error"/>
</p>

The max extent of the WFS data can be added to the map with the checkbox `Draw the extent on the map`.

### 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 `Keep data intersecting the extent` or choose to clip all features with the extent by checking `Clip data intersecting the extent.`

### 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.

#### 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` (default), `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.

### 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. An OpenStreeMap basemap is automatically added to the project if there is no layer in it. So the user can draw a rectangle.


```{toctree}
---
caption: Contribution guide
maxdepth: 1
---
development/extraction_tool
development/roadmap
development/contribute
development/environment
development/documentation
development/translation
development/packaging
development/testing
development/history
```