wcps 0.1.0

Python client library for WCPS (OGC Web Coverage Processing Service) backends.

Overview

The OGC Web Coverage Processing Service (WCPS) standard defines a protocol-independent declarative query language for the extraction, processing, and analysis of multi-dimensional coverages (datacubes) representing sensor, image, or statistics data.

This Python library allows to dynamically build WCPS queries and execute on a WCPS server.

Installation

pip install wcps

Examples

Derive an NDVI map from red and near-infrared bands of a Sentinel-2 datacube, threshold the very green areas (values greater than 0.5) as true values (white in a PNG), and save the result as a PNG image.

from wcps.service import Service
from wcps.model import Datacube

# Let S2_L2A be a 3D coverage with nir and red bands;
# slice it at "2025-01-15" on the time axis, getting a 2D map
cov = Datacube("S2_L2A")["time", "2025-01-15"]
# NDVI formula
ndvi = (cov.nir - cov.red) / (cov.nir + cov.red)
# threshold NDVI values to highlight areas with high vegetation
vegetation = ndvi > 0.5
# encode final result to PNG
query = vegetation.encode("PNG")

service = Service("https://ows.rasdaman.org/rasdaman/ows")

# execute the query on the server and get back the response
response = service.execute(query)

# alternatively, save the content of the response into a file
response = service.execute(query,
                           output_file='vegetation.png')

We can calculate the average NDVI as follows:

cov = ...
# NDVI formula
ndvi = (cov.nir - cov.red) / (cov.nir + cov.red)
# get average NDVI value
query = ndvi.avg()

service = ...
response = service.execute(query)

print(f'The average NDVI is {response.content}')

Contributing

The directory structure is as follows:

• wcps - the main library code
• tests - testing code
• docs - documentation in reStructuredText format

Tests

To run the tests execute:

pytest

Documentation

To build the documentation:

# install needed dependencies
pip install wcps[docs]

cd docs
make html

The built documentation can be found in the docs/_build/html/ subdir.