About
GLACE Viewer is a web map for exploring annual Sentinel-1 coherence and
backscatter composites. It provides a visual overview of the data, with glacier
outlines and terrain for context.
You can choose among the available years, VV or VH polarization, false color,
and quality layers. The map also offers adjustable raster opacity, vector or
satellite basemaps, hillshade, 3D terrain, glacier inventories, and
the catalog's tile grid. Available raster choices come from the catalog.
Click the map to read the layer's value there. The address keeps your choices,
so a copied link opens the same view.
The archives carry quantized values, colored in the browser, so you can change
the color map and its range. They are lossy 8-bit WebP, so for numerical analysis use the COG assets linked from the
STAC items in the browser above.
Run locally
You need the Node version in .node-version and, for the glacier
inventory overlays, tippecanoe on your
PATH (brew install tippecanoe on macOS; elsewhere build it from source).
Run these commands from the repository root. First, install the page's
libraries and build the glacier inventory tiles from the committed GeoJSON:
npm ci
npm run build-tiles
Then, serve the website:
npm run serve
Open http://localhost:8000/. Use localhost: the configured basemap's
local-development access does not work with 127.0.0.1. The viewer reads GLACE
rasters from Source Cooperative by default; you do not need a local copy.
To view a local catalog, mount its root and select it in the URL:
npm run serve -- --tiles-dir /path/to/catalog-root
Then open http://localhost:8000/?tiles=tiles. The directory should contain
mosaics/collection.json; pointing at the archive directory alone is not enough.
Repository
The page uses HTML, CSS, and native JavaScript modules with MapLibre GL JS.
There is no frontend build step or application server. Raster and inventory
PMTiles are read through HTTP range requests; the supplied development server
supports those requests.
index.html, style.css, js/: the viewer.site-config.js: deployment settings, including the catalog URL.data/: glacier inventory GeoJSON and its metadata; PMTiles are generated.scripts/, tests/: local serving, tile generation, and checks.
Run the tests with npm test. GitHub Actions tests changes and
publishes the site to GitHub Pages on pushes to main. See AGENTS.md
for architecture, data contracts, and maintenance guidance.
Data and credits
The map uses Protomaps with
OpenStreetMap data or
Esri World Imagery
for its basemap, and Mapterhorn for terrain.
Glacier outlines come from the
Swiss Glacier Inventories 2016 and 2023,
Austrian Glacier Inventory 5,
Paul et al.'s Alpine Glacier Inventory,
and Randolph Glacier Inventory 7.0 (Alps).
Source credits appear on the map. Inventory citations and licenses are available
beside each toggle and in data/inventories.json.
The viewer code is MIT licensed. The glacier inventories, basemaps,
and elevation data come from third parties and have their own licenses.
Their attribution is displayed in GLACE Viewer.
Third-party color maps
The cmc.* color maps in js/colormaps.js are Fabio Crameri's Scientific
colour maps, MIT License: Crameri, F. (2018). Scientific colour maps. Zenodo.
https://doi.org/10.5281/zenodo.1243862. viridis, magma and cividis come from
matplotlib (CC0). Regenerate the file with uv run scripts/colormaps.py > js/colormaps.js.
