Geospatial data visualization

For a deeper level of visualization of assets, you can download and render them in third-party GIS software.

Step 1. Open assets in QGIS

Step 2. Add basemaps

Step 3. (optional) Pansharpen images

Step 4. (optional) Convert images

Download and install free open-source software QGIS. You can add assets by downloading or streaming them.

For more information on how to use QGIS, see the QGIS documentation.

Download assets or processing results.

The unpacked folders will contain different file formats depending on the source of the data. Find the file you’ll visualize by analyzing the folder structure:

• DIMAP folder structure

  This folder structure is used for Pléiades and SPOT collections. It consists of several folders with different prefixes:

  • _MS_ for analytic multispectral assets
  • _P_ for analytic panchromatic assets
  • _PMS_ for display assets

  For visualization, use corresponding XML files with DIM_ prefixes inside these folders instead of TIFF or JPEG files, because they may be not georeferenced.

• Simple folder structure with GeoTIFFs

  If the unpacked folder has a simple structure, use TIFF files. GeoTIFF is the most common geospatial data file format, a single file that contains one or multiple color bands.

Drag the required file (XML or TIFF depending on the source) into a QGIS project.

1. Copy the streaming link.
2. In QGIS, in the top navigation menu, click Layer → Data Source Manager.
3. Go to the Raster or Vector tabs, depending on the type of data you want to visualize.
4. Select Protocol: HTTP(S) and paste the streaming link into the URI field. Click Add.

The STAC asset will be added as a new layer.

Optionally, you can use different basemaps as location references for your image in QGIS.

1. In QGIS, in the top navigation menu, click Plugins → Manage and Install Plugins.
2. Search for QuickMapServices. Select it and click Install Plugin.
3. In the top navigation menu, click Web →  QuickMapServices → Settings.
4. Go to More services and click Get contributed packages.
5. Click  QuickMapServices and select a basemap of your choice.

You can use the GDAL pansharpening tool on QGIS to pansharpen optical imagery.

1. In QGIS, in the top navigation menu, click Processing → Toolbox to open the toolbox sidebar.
2. Import the panchromatic and multispectral bands.
3. In the toolbox search bar, search for GDAL → Pansharpening and select it.
4. Choose the multispectral band as the Spectral dataset and the panchromatic band as the Panchromatic dataset.
5. Click Run.

The pansharpened image will be displayed as a new layer in your QGIS project.

The GDAL pansharpening tool can only apply standardized grey weights, which aren’t optimized for the imagery. You can perform pansharpening with sensor-optimized grey weights on the UP42 platform.

Optionally, you can convert raster images to PNG, JPEG, or other standard image formats on QGIS.

1. In QGIS, in the top navigation menu, click Project → Import/Export →  Export Map to Image.
2. In Extent, click Calculate from Layer and select the layer you want to convert. By default, it only converts the current map view.
3. Adjust the scale and resolution. Click Save.
4. Specify the file name, directory, and format using which you want to save your image. Click Save.

My image appears colorless, bland, or half transparent

Sometimes QGIS interprets the near-infrared band as the alpha band. The optional alpha band in RGB images is used for giving transparency to specific parts of the image.

1. In QGIS, right-click the image layer and click Properties.
2. Go to Transparency.
3. Under Custom transparency options, select None instead of an image band. Click Apply.

My image has a lot of white spots where there should be pixels

Sometimes in products of the display radiometric processing level, the noData value is set to 0. At the same time, some very dark pixels are also set to 0. This causes this white spot effect.

1. In QGIS, right-click the image layer and click Properties.
2. Go to Transparency.
3. Under No Data Value, clear the No data value checkbox. Click Apply.

My image is too dark or too bright

There isn’t a default setting for images. Manually change different option values to achieve a satisfactory look.

1. In QGIS, right-click the image layer and click Properties.
2. Go to Symbology.
3. Under Band rendering, go to Contrast enhancement and select Stretch to MinMax.
4. Expand the Min/Max Value Settings drop-down pane.
5. Try changing values for Cumulative count cut and Mean standard deviation. Click Apply after each iteration to see the result.

My Pléiades or SPOT images are rotated 90° counterclockwise

You rendered a JPEG file instead of an XML file with a DIM_ prefix. For more information about the DIMAP format, see Pléiades and SPOT 6/ 7 Format Delivery.