The QGreenland configuration represents the processing that needs to be done to convert source datasets in to final outputs ready for use by QGreenland. The configuration can be found at:


Within this directory, there is a subdirectory for datasets, layers, and helpers. Additionally, the file is required in the config directory. You can optionally add any number of other files, e.g., to the configuration directory.

Configuration models can be found at:


Project config defines the project crs (EPSG) and any boundaries that will be used to clip data for this project.

Datasets config

Dataset configurations define a unique id, metadata, and a list of assets.



An asset represents a file or files in a dataset that will be used to create a single layer. A layer currently cannot use more than one asset as its input.

There are various types of assets. Some useful ones are:

  • HttpAsset: Downloads from a list of HTTP urls.

  • CmrAsset: Queries NASA CMR for a single granule_ur in a given collection_concept_id and downloads it.

  • CommandAsset: Runs an arbitrary command args to download or create data files.

  • ManualAsset: Accesses data that has been manually downloaded by a human in to the private archive. This is required for datasets which can not be fetched programmatically, for example: because they’re behind a GUI authentication screen; because an asynchronous ordering system must be used to access the data; or because the data was provided directly by a scientist over e-mail and is not hosted anywhere. We prefer to avoid or eventually fully eliminate the use of data in this category.


Link to API docs?

You can find the full set of available asset types here.

Layers and layer groups config

Layers in qgreenland/config/layers are organized into a directory structure which mirrors the QGIS Layers Panel tree structure. Each directory may optionally contain a settings file which is documented below in the Layer group settings section.

Layers can be represented in python files with any name. ConfigLayer objects will be found in those python files when written either as plain named variables, e.g. foo = ConfigLayer(...) or when present in a tuple or list, e.g. layers = [ConfigLayer(...) for thing in things].

The layer’s title will determine how the layer is displayed in the QGIS Layers Panel and the description determines the hovertext for that same layer in the QGIS Layers Panel.

Layer steps

Layers are created in a series of steps. The final result of the steps must be a GeoTIFF (.tif file) for raster layers, and a GeoPackage (.gpkg) for vector layers.

Each step is a command (e.g. gdalwarp or ogr2ogr) run against the output of the previous step. The first step acts on the chosen input.asset.

Within a step configuration, “runtime variables” are used to populate values that are not known at configuration-time, for example the WIP directories that will be used to store the inputs and outputs of the step. Runtime variables are designated by braces { } surrounding the variable name. Only the following runtime variables are legal:

  • {input_dir}: The output directory of the previous step or, for the first step, the layer’s fetched input.asset location.

  • {output_dir}: The output directory of this step.

  • {assets_dir}: In this repository, qgreenland/assets.

Layer group settings

Each layer group can optionally have a file inside its directory which determines settings for only that group. If the file is omitted, defaults are used (see here for default values).

This file is most commonly used for specifying the order in which the layer group’s contents will be displayed in QGIS. If order is not specified, contents are displayed alphabetically with groups first.

An example settings file shows that layers are represented with a leading : to differentiate layers from groups in the same list.

Configuration helpers

Helpers are arbitrary python code to allow code-sharing between configuration modules. The following categories of helpers exist in subdirectories:

  • layers: Helpers and variables for generating layer configuration objects.

  • steps: Helpers which return a step or steps configuration objects.

  • ancillary: JSON data to support helpers.

Configuration lockfile

Use inv config.export > qgreenland/config/cfg-lock.json to refresh the configuration lockfile. This allows us to compare the results of configuration changes against the previous state.