Running the step

Goal¶

Run crop in the same Hatch environment used by the practice notebook. The notebook is stored at practice-labs/1-Application_Steps/crop.ipynb.

Requirements¶

Install Python 3.12 or newer, Hatch, and Task. The remote STAC item and its assets must be reachable. See developer tooling for the available tasks.

Register the notebook kernel¶

From the checkout root, run:

task kernel:install TOOL=crop

Select Bash (crop Hatch) in Jupyter or VS Code. This kernel uses the package's default Hatch environment. An ordinary Bash kernel can also activate that environment using the commands below. Run the workspace setup from inside the checkout so Git can locate its root.

Configure the workspace¶

export WORKSPACE="$(git rev-parse --show-toplevel)"
export RUNTIME=${WORKSPACE}/runs
mkdir -p "${RUNTIME}"
cd "${RUNTIME}"

Outputs are written to runs/ in the current checkout.

Activate the Hatch environment¶

cd "${WORKSPACE}/water-bodies/command-line-tools/crop"
hatch env create default
source "$(hatch env find default)/bin/activate"
cd "${RUNTIME}"

which python
which crop
crop --help

Hatch installs the Python project and its dependencies; a separate pip install cell is unnecessary. Activation keeps the console command available after changing to the output directory.

Run the step¶

crop \
    --input-item "https://earth-search.aws.element84.com/v0/collections/sentinel-s2-l2a-cogs/items/S2B_10TFK_20210713_0_L2A" \
    --aoi='{"type":"Polygon","coordinates":[[[-121.399,39.834],[-120.74,39.834],[-120.74,40.472],[-121.399,40.472],[-121.399,39.834]]]}' \
    --epsg "4326" \
    --band green

crop \
    --input-item "https://earth-search.aws.element84.com/v0/collections/sentinel-s2-l2a-cogs/items/S2B_10TFK_20210713_0_L2A" \
    --aoi='{"type":"Polygon","coordinates":[[[-121.399,39.834],[-120.74,39.834],[-120.74,40.472],[-121.399,40.472],[-121.399,39.834]]]}' \
    --epsg "4326" \
    --band nir

The notebook supplies Polygon JSON. Crop masks pixels outside the polygon, retains the source pixel datatype, and writes LZW-compressed COGs. The command also accepts a comma-separated bounding box. --epsg 4326 describes the AOI coordinate system.

Expected outcome¶

The step adds these files under runs/:

crop_green.tif
crop_nir.tif

Earlier steps' outputs remain available.

Finish the session¶

deactivate

Keep the Hatch environment for subsequent runs. The pip-based scripts under scripts/ remain an alternative for manual shell use.