---
license: mit
tags:
- geospatial
- satellite
- remote-sensing
- time-series
- neural-compression
---

  # GeoNDC Sample Data

  Sample `.gndc` files for use with [pygndc](https://github.com/jianboqi/pygndc) — a neural network-based compression format for geospatial time-series data.

  ## What is .gndc?

  A `.gndc` file stores 4D satellite imagery (Time × Height × Width × Bands) compressed by neural networks, achieving up to **300:1 compression ratios** while supporting:

  - Reconstruction at **any** time point (continuous temporal interpolation)
  - Fast random pixel access at any timestamp
  - Analytic spatial/temporal gradients

  ## Usage

  ```python
  pip install pygndc

  import pygndc

  with pygndc.open("S2_sample_2022_to_2025.gndc") as ds:
      print(ds)                                        # metadata
      frame = ds.read(t=0)                             # (H, W, C)
      frame = ds.read_at_time("2024-06-15")            # continuous interpolation
      series = ds.sample(lon=116.825, lat=40.486)      # (T, C) time series
      ndvi = ds.ndvi(t=0, red_band=2, nir_band=3)     # (H, W)
      ds.to_tif("output.tif", t=0)                     # export GeoTIFF

  Online Viewer

  Browse .gndc files directly in the browser (no installation needed):
  https://www.geondc.org/viewer/

  Links

  - pygndc: https://github.com/jianboqi/pygndc
  - Website: https://www.geondc.org