Application Package - Background

The Application Package defines a workflow for detecting water bodies based on Normalized Difference Water Index (NDWI) and Otsu threshold using Sentinel-2 data.

The key components of this CWL document are:

• Name: Water bodies detection based on NDWI and the Otsu threshold.
• Description: Workflow for detecting water bodies based on NDWI and Otsu threshold applied to a single Sentinel-2 Cloud-Optimized GeoTIFF (COG) SpatioTemporal Asset Catalog (STAC) item.

• Inputs:

  • aoi: Area of interest as a bounding box.
  • epsg: EPSG code (default: "EPSG:4326").
  • bands: Bands used for NDWI (default: ["green", "nir"]).
  • item: Reference to a STAC item.

• Outputs:

  • stac_catalog: Output directory containing the STAC catalog.

• Steps:

  • node_detect: Executes the detect-water-body tool with specified inputs and produces a STAC catalog in the output directory.

• Tool: detect-water-body:

  • A CommandLineTool written in Python that uses various libraries such as rasterio, skimage, pyproj, shapely and loguru.
  • It performs operations like cropping, thresholding, and creating a STAC catalog for the detected water bodies.
  • It takes inputs like STAC item URL, area of interest, EPSG code, and band names.

• Tool Requirements:

  • Uses Docker.
  • Specifies resource requirements (coresMax: 1, ramMax: 512).
  • Sets up initial working directory with an entry script (app.py).

• Execution:

  • The workflow runs the detect-water-body tool with specified inputs.
  • Generates a STAC catalog with the detected water bodies.
  • Cleans up temporary files after completion.