California sky

GOES-18 ABI

LAT—

LON—

100 km

How this view is made

The full-disk GOES-18 image is a 21,696 × 21,696 grid of scan angles, not a map. Every pixel is traced from the satellite through the WGS-84 ellipsoid, then resampled onto a Web Mercator grid over California.

Source: —
Native resolution: 500 m at nadir, ~560 m over California
Rendered grid: —
Projection: EPSG:3857 — resampled per-pixel from ABI scan angles
Pipeline: scripts/render_california.py

True color +detail

Band 2 sees cloud texture that the colour composite smooths out. This layer adds a small, masked amount of that fine structure to the GeoColor luminance, keeping the colours unchanged. It is not extra resolution — both layers come from the same 500 m pixels — so it reads only when you zoom past the native scale. The transfer is suppressed along the state borders and degree graticule, which are drawn into the band-2 product itself.

The loop

A poller checks NOAA every two minutes and keeps the last 24 hours — 144 frames, one every ten minutes. Each frame is warped once and stored as two WebP levels, so scrubbing never waits on a download.

Why not reproject in the browser?

A full-disk frame is 470 megapixels. Doing that warp per frame in WebGL would download 58 MB before the first cloud appears. Pre-warping once, then shipping a 2 MB WebP pyramid, opens on a phone in under a second.

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