DataLoader

DataLoader is the imagery-acquisition front end for eMapR pipelines (LandTrendr, BULC-D, BugNet, foundation-model work, ...). A pipeline describes the imagery it needs in a small YAML config: provider, sensor, area, years/season, bands. DataLoader then finds it, downloads it, and writes plain GeoTIFFs plus a versioned, machine-readable manifest recording what was acquired, where it came from, and what was done to it. Downstream code reads the manifest and never needs provider-specific code or filename parsing.

config.yaml ──► DataLoader ──► provider (USGS ARD, Planetary Computer, Earth Search, ...)
                    │
                    └──► <output.dir>/  GeoTIFFs + manifest.json + items.jsonl + source metadata
                                              │
                                              └──► your pipeline

• One tool for small pulls and big archives. A one-month AOI and a 35-year, 23-tile Landsat archive use the same command and produce the same output layout. The difference is only in the config.
• Resumable and updatable. If a run is interrupted, run the same command again and it picks up where it stopped. Leave the end year open and re-running later adds the new imagery.
• Provider-independent. Change provider: to switch sources. Before downloading, DataLoader checks that the provider supplies the scientific product you asked for.
• Nothing hidden. Cloud masking is off unless you ask for it. QA bands can be kept, source metadata is saved verbatim, and failures are recorded rather than silently dropped.

Install

Python 3.9 or newer. Everything installs from pip; GDAL comes bundled with the rasterio wheel.

git clone https://github.com/eMapR/data-loader.git
cd data-loader
python3 -m venv .venv && source .venv/bin/activate
pip install -e .            # add '.[gee]' for Google Earth Engine, '.[dev]' for tests
data-loader --version

Five-minute example

examples/quickstart.yaml pulls every Landsat scene over a small Oregon AOI for July 2023 from Microsoft Planetary Computer. It needs no account.

version: 1
provider: planetary_computer
sensors: [landsat]
aoi:
  upper_left: [-122.4327, 44.2860]     # [lon, lat]
  lower_right: [-122.3426, 44.2315]
time:
  start_date: 2023-07-01
  end_date: 2023-07-31
temporal_mode: scene                   # or annual_composite
output:
  dir: output/quickstart
  bands: [red, nir]
  indices: [ndvi]
  qa_band: true

data-loader validate examples/quickstart.yaml   # checks the config, no network
data-loader run examples/quickstart.yaml        # ~1 minute; prints the manifest path
data-loader status output/quickstart

output/quickstart/
  manifest.json            what this dataset is: request, product, bands, grids, processing, counts
  items.jsonl              one line per acquisition: date, sensor, source ID, status, files, checksums, provenance
  request.yaml             the exact request that produced it
  metadata/<provider>/     each source item's original metadata record, verbatim
  landsat/aoi/2023/2023-07-04_LE07_L2SP_045029_20230704_02_T1_bands.tif
  landsat/aoi/2023/2023-07-04_LE07_L2SP_045029_20230704_02_T1_indices.tif
  ...

Reading it from Python:

from data_loader import open_dataset
import rasterio

ds = open_dataset("output/quickstart")
print(ds.manifest["bandSets"]["landsat"]["bands"])      # band order, dtype, scale/offset, nodata, QA meaning
for path, item, f in ds.files(start="2023-07-10"):
    with rasterio.open(path) as src:
        red = src.read(1)
    print(item["date"], item["itemId"], item["eo:cloud_cover"])

Adapt the example: edit the corners, dates, and bands, and point output.dir (or --output-dir) somewhere new.

Choosing a provider

Provider	Data	Account	Use it for
usgs_ard	Landsat 4–9 C2 U.S. ARD SR, straight from USGS	USGS EROS + M2M token	Preferred for Landsat time series and archives. USGS is the authoritative source, it covers Landsat 4–9, and every observation sits on a fixed 5000×5000 px Albers tile grid.
planetary_computer	Landsat 5–9 C2 L2 and Sentinel-2 L2A	none	Quick AOI pulls and Sentinel-2 with no setup.
aws_earth_search	Sentinel-2 L2A (free); Landsat (AWS Requester Pays)	none for Sentinel-2	Sentinel-2. Its Landsat bucket bills an AWS account.
gee	Landsat C2 L2, Sentinel-2 SR (harmonized)	Earth Engine project	Exploratory small AOIs. Requests are capped at ~48 MB each.
glad_ard	GLAD 16-day Landsat ARD, 2020+	none	GLAD's normalized 16-day composites specifically.
usgs_m2m	Landsat C2 L2 scene bundles	USGS EROS + M2M token	Experimental: the bundle download path has not been verified end to end.

The full comparison, with caveats such as DataLoader's Planetary Computer Landsat path covering Landsat 5–9 only and how Sentinel-2 processing versions are handled, is in docs/providers.md. The USGS account setup is in docs/getting-started.md.

Archives: whole tiles, full history

For a persistent archive, request whole USGS ARD tiles. DataLoader then stores each observation exactly as USGS distributes it: uint16 DN with QA_PIXEL, no cloud masking, and no resampling. Downstream pipelines make their own cloud, shadow and snow decisions.

aoi:
  tiles: [h003v004, h003v005]
time:
  start_year: 1990                     # no end_year: through today, updatable
temporal_mode: scene
output:
  encoding: native
  bands: [blue, green, red, nir, swir1, swir2]
  qa_band: true

See examples/usgs_ard_tile_archive.yaml and eMapR's Oregon archive examples/oregon_landsat_ard_archive.yaml, along with docs/large-jobs.md for runtime, storage, tmux, resume and updates. The Oregon archive is about 89,000 observations, takes about 3–4 weeks on one USGS account, and needs roughly 5–6 TB.

Documentation

Getting started	Install, credentials for each provider, first runs
Configuration	Every config key; years, seasons and dates; AOIs and tiles; migrating old configs
Providers	What each provider serves, accounts and costs, when to choose which
Outputs	Directory layout, manifest.json and items.jsonl field by field, reading data, masking with QA
Large jobs	Archives, runtime and storage, resume, updates, failures
Troubleshooting	Common errors and fixes
Development	Architecture, adding a provider, tests, benchmarks and development history

Example configs live in examples/. Run the tests with pytest (they need no network or credentials).

Status

Version 1.0. The config schema (version: 1) and the output manifest (dataloader-manifest 1.0) are the stable interfaces; see CHANGELOG.md. Planned next: vector (GeoJSON) AOIs, and Sentinel-2 directly from the Copernicus Data Space Ecosystem.