GRASS / FastGIS toolbox

The acoustic and terrain analysis in GroundTruther is powered by a remote GRASS GIS service exposed through the FastGIS GRASS API (https://api.fastgis.eu). The toolbox lets you connect to it, manage GRASS environments, set the analysis region, push data in and out, and run any GRASS module — without installing GRASS locally.

The GRASS API dialog: the endpoint, the environment picker, and the active environment with its env_id — the handle every subsequent call is scoped to.

Connect

In Settings → Processing, set:

• grass_api_endpoint — the API base URL (default https://api.fastgis.eu).
• grass_api_key — your API key (fgk_…), sent on every request.

Environments

Every operation runs against an environment — a server-side workspace that binds a GRASS location (a coordinate system) and mapset to your account. In the GRASS settings dialog you can:

• List and select your environments (the active one is what tools act on).
• Create a new environment from an EPSG code or by uploading a georeferenced dataset (whose CRS seeds the new location — the file is also imported as a layer).
• Create mapsets within an environment.

Computational region

GRASS modules honour the current computational region. You can:

• Set the region from a box drawn on the map (coordinates are reprojected to the environment's CRS automatically), or align it to a layer.
• Show/hide the current region on the map with the Region toggle — it outlines the active environment's region without changing it.

The current computational region rendered on the canvas.

Move data in and out

• Import a file into the active environment (raster or vector) from disk.
• Send a loaded QGIS layer to the environment: right-click it in the Layers panel → Send to active GRASS environment (it's reprojected to the environment's CRS on the way).
• Add GRASS rasters to QGIS from the layer table (button or right-click) — fetched as GeoTIFF and added to your project.

Run GRASS modules

GroundTruther builds a module dialog on the fly from the module's own interface description — so virtually any non-blacklisted GRASS module is usable, not just a hard-coded few.

A dialog generated from a GRASS module's interface (here r.geomorphon).

• Pick a module: type into the module search box and choose from the autocomplete over the full GRASS catalogue; the form is built from its schema.
• Quick presets: buttons for common seafloor modules (r.geomorphon, r.param.scale, …).
• Run asynchronously: modules run on the server with live progress and a Cancel option, so the UI stays responsive on large DEMs.
• Outputs return to QGIS: rasters created by a run are pulled back and added to your project automatically; stdout/stderr appear in the output panel.

How it works under the hood

The plugin talks to an environment-scoped, authenticated REST API; module UIs are generated from each module's interface description, runs are queued as background tasks, and results are retrieved as GeoTIFFs. See the Architecture page for the data-flow diagram.

Settings summary

Setting (Processing)	What it is
grass_api_endpoint	FastGIS API base URL.
grass_api_key	API key sent as X-API-Key.
gpu_avaibility	Whether a CUDA GPU is available for spatial selection acceleration. (Spelled exactly like that in the file.)

Full descriptions, defaults and failure modes: settings reference → Processing.

The roughness service reuses these credentials

Seafloor Roughness sends its requests to the same FastGIS endpoint with the same API key, so configuring the toolbox configures roughness too.