In this blog post we will walk you through the new feature we added in QGIS to access, browse and filter SpatioTemporal Asset Catalog (STAC) data.
STAC stands for SpatioTemporal Asset Catalog. It's essentially a common language to describe geospatial information, making it easier to work with, index, and discover. You can think of it like a standardised way to organise and access any kind of geospatial data, whether it's satellite imagery, drone footage, or sensor readings.
STAC provides a set of specifications for describing geospatial assets (like satellite images) in a consistent way. This includes information about the asset's location, time of capture, and other relevant metadata. It also makes it easier to find and use geospatial data from different sources. By standardising the metadata, STAC allows users to search for data using common criteria, regardless of where the data comes from.
The key components of STAC:
There have been several plugins in QGIS to use with STAC. But often those plugins are built around a certain data provider and do not make use of the full STAC capabilities. Therefore, we decided to implement STAC as a core QGIS data provider. In QGIS 3.40, we initially added support for static STAC servers. In simple terms, static STAC does not include an API, so it is not possible to search based on spatial or temporal extent. Furthermore, in QGIS 3.42 you can browse and filter STAC catalogs.
To use the features described below, you will need QGIS 3.42 or later.
There are several open catalogs available online. For more catalogs, you can visit https://radiantearth.github.io/stac-browser
For the purpose of the examples below, we use Eco Data Cube (https://s3.eu-central-1.wasabisys.com/stac/odse/catalog.json) and SnapPlanet (https://tamn.snapplanet.io/) catalogs
You can add a new STAC connection either through the Browser Panel or Data Source Manager:
If you extend the connection, you should be able to see some collections:
You can expand a collection, you will be able to see items within that collection:
To see details of an item, right click and select Details. This will display the metadata, coverage, STAC extension, etc for the item.
If the item is a Cloud Optimized format (e.g. COG), you can simply drag and drop it in QGIS canvas to view it. If it is a flat file, you need to first download the item. Right-click on the asset and select Download….Select the path and the objects you want to download. It contains the main dataset and other auxiliary data (e.g. style, thumbnail, etc).
After download, you can add the TIFF file to QGIS:
The above method is more suitable for static collection. But if you want to search the data, you can use the Data Source Manager:
In the Data Source Manager, under STAC, create a new connection for SnapPlanet (https://tamn.snapplanet.io/).
When you connect you can see millions of assets! It is difficult to go through all the assets and find the right dataset. If you click on Filters … you will be presented with a new window to cut down the data spatially and temporally:
Once you filter data, you can also see the dataset footprints on the QGIS map:
When you select the items in the Data Source Manager, the footprint gets highlighted (in red). You can then download the asset(s) related to the item and visualise it in QGIS.
This work was carried out thanks to funding from KoBold Metals (https://www.koboldmetals.com/). There are other items on our wishlist,which we would like to add but they were not within the scope of the project or a core part of STAC:
If you are interested in sponsoring those features to appear in the future releases of QGIS, please contact us (info@lutraconsulting.co.uk).
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Lutra Consulting is a QGIS-focused expert provider of geospatial software development, consulting, training, and support services.
