Contributing

Contributing to the catalogue is straightforward. You can propose an index through a GitHub issue or add it directly in a code contribution.

Before proposing a new index, read the AI and Scientific Validation Policy.

The easiest way

Open a new spectral index issue with the following information:

• short_name: Short name of the index, such as "NDWI".
• long_name: Long name of the index, such as "Normalized Difference Water Index".
• formula: Expression for the index, such as "(N - G)/(N + G)".
• reference: Link to the index reference, paper, or DOI.
• application_domain: One of vegetation, burn, water, snow, urban, soil, clouds, kernel, or radar.
• date_of_addition: Date of addition in YYYY-MM-DD format.
• contributor: GitHub profile URL or email address.

The formula must use the standard variables supported by the catalogue. Common variables include:

Description	Standard
Aerosols	A
Blue	B
Green 1	G1
Green	G
Yellow	Y
Red	R
Red Edge 1	RE1
Red Edge 2	RE2
Red Edge 3	RE3
NIR	N
NIR 2	N2
Water vapour	WV
SWIR 1	S1
SWIR 2	S2
Thermal	T
Thermal 1	T1
Thermal 2	T2
Gain factor	g
Canopy background adjustment	L
Coefficient 1 for the aerosol resistance term	C1
Coefficient 2 for the aerosol resistance term	C2
Exponent used for OCVI	cexp
Exponent used for GDVI	nexp
Weighting coefficient used for WDRVI	alpha
Weighting coefficient used for ARVI	gamma
Weighting coefficient used for MBWI	omega
Soil line slope	sla
Soil line intercept	slb
Photosynthetically Active Radiation	PAR
Slope parameter by soil used for NIRvH2	k
NIR central wavelength	lambdaN
Red central wavelength	lambdaR
Green central wavelength	lambdaG
Kernel of variables A and B	kAB

The complete, authoritative list is defined by the Bands enum in src/utils.py.

Contributing through code

1. Fork and clone the repository.

2. Create and activate an isolated Python environment. For example, with Conda:

   conda create --name asi-dev python=3.10
   conda activate asi-dev
   python -m pip install -r requirements-test.txt

   Alternatively, using Python's built-in venv:

   python -m venv .venv
   source .venv/bin/activate
   python -m pip install --upgrade pip
   python -m pip install -r requirements-test.txt

   On Windows, activate the virtual environment with .venv\Scripts\activate.

3. Create a development branch:

   git switch -c name-of-development-branch

4. Add the index to the SpectralIndices catalogue in src/indices.py:

   SeLI = SpectralIndex(
       short_name="SeLI",
       long_name="Sentinel-2 LAI Green Index",
       formula="(N2 - RE1) / (N2 + RE1)",
       reference="https://doi.org/10.3390/s19040904",
       application_domain="vegetation",
       date_of_addition="2021-04-08",
       contributor="https://github.com/davemlz",
   )

   SpectralIndex is a Pydantic model that validates the submitted metadata and formula. The formula must use supported bands and parameters.

5. Run the tests:

   pytest test

6. Commit and push the changes:

   git add src/indices.py
   git commit -m "Add short-name-of-the-index"
   git push origin name-of-development-branch

7. Submit a pull request with the test results and scientific reference.