Getting topographies
====================

One of the needs that may arise is the use of topography for analysis.

If conducting a topographic survey is not an option, we would like to obtain this data somehow.

Below we will show how to obtain satellite-derived topographic data.

Using QGIS with OpenTopography DEM Downloader plugin

1. Installing components
    1. The first component you will need is the QGIS software installed on our machine. You can access the following link to download QGIS: <https://qgis.org/download/>.
    2. After download QGIS, follow the instructions in installer to install it in your machine. After do that, go to next step.
    3. Now, we will need the OpenTopography DEM Downloader plugin. You can access the following link <https://plugins.qgis.org/plugins/OpenTopography-DEM-Downloader/> to download the plugin ZIP file.
    4. At certain point in the next steps, will be requested to use an API key. So, find the `Request an API key` button in the following link <https://opentopography.org>, and follow instruction to get the key. Save it.
    5. Open your QGIS. In the most upper menu, click the `Plugins` button, and then click the `Manage and Install Plugins...` button. In the windows appeared, click the `Install from ZIP` button in the left sidebar and a new context will appear in this window. Locate the button `...`  in this context and click it. Then, locate the ZIP file you downloaded earlier and select it.
    6. Click the `Install Plugin` button.
    7. Restart QGIS.
2. Setting the coordinates
    1. In QGIS, click the `project` button in the most upper menu, click the `new` button in opened dropdown.
    2. In the most upper menu, click `HCMGIS` button, go to `Basemaps` option and then select `Google Satelite`.
    3. In bottom right, click the `current CRS` button to open a new window. Now, select the Coordinates Reference System that best suits your region of interest.
3. Selecting the area
    1. Go to the location of interest.
    2. Position the camera so that the entire area of ​​interest is contained within the viewport.
4. Extracting the altimetry
    1. You can access the plugin by two ways:
        - In the most upper menu, click the `Raster` button, and then click the `OpenTopography DEM` option, and finally click the `OpenTopography DEM Downloader` button.
        - In one of the upper menus, locate the plugin button and click it.
    2. In the window, select the `Copernicus Global DSM 30m` option in `Select DEM to download` dropdown.
    3. In the next field, click in the arrow to open more options. Select `Use Current Map Canvas Extent` options.
    4. In the next field, put the API key obtained previously.
    5. Click `Run` button.
5. Exporting a DEM
    1. In the layers menu, right click in generated layer, select `Export` option, and then click `Save As...` button.
    2. In format options, select `GeoTIFF` option.
    3. In file name option, select where save the file.
    4. Press `ok` button.

.. note::
    Tutorial wrote in version 3.36.3 of QGIS.