sondage

Time and depth over cloud arrays. Datasets in Icechunk, Zarr and Cloud Optimized GeoTIFF are read by byte ranges in the browser or in Node, set on one clock, and drawn as surfaces, ocean shells, box walls and sections, or cut as a section and block diagram, in any CRS proj4js knows: on a globe, or unfolded onto an azimuthal equidistant or Spilhaus map.

Part of allboa: the org's design record and agent brief are in allboa/design (start with its AGENTS.md), and the scene spec is allboa/scenespec. Extracted from hypertidy/playproj with its history (the 4D and cutaway pages, their readers and the core they stand on); playproj keeps the explainer pages and imports this package.

Layout

Path	What
src/core/	Pure modules (no DOM, canvas or three.js; checked by test/check-pure.mjs): axes, clock, windows, unpacking, cache and isolines (fourd.js); sections and blocks (cutaway.js, mosaic.js); CRS and grid inference (storecrs.js, structure.js, grids.js, chunkgrid.js); palettes, geoid, projection helpers
src/scene/	three.js: the frame every layer is placed in (globe, azimuthal equidistant or Spilhaus map, unfold between them, range, cuts, picking back to the Earth; frame.js), the layers (a surface over a whole grid; an ocean box as shell, walls, sections and rim; contour lines through the same cells; layers.js), the cutaway's section bands and block diagram (block.js), textures painted through palettes (paint.js), stage, URL hash state, share and embed links
src/read/	Sources: one interface over Icechunk, Zarr, COG series and synthetic data (source.js); one COG per time step read at an overview level, or one COG with no time axis such as a topography or an RGB chart (cog.js); stores described by their own metadata (store.js); the per-host read ledger (hosts.js)
fourd.html, cutaway.html	The two viewers
data/fourd/stores.json	Example registry
examples/block.html	A block diagram from made-up layers, with no data: drawBlock() on its own

A Source

Every dataset, however it is found, opens as the same thing: a description (dims with roles t, z, y, x; coordinates; time as dates; depth with its direction; units, scale, offset, fill) and a read by index windows that returns physical values, rows by columns.

import { openRegistry, openUrl } from "sondage/read";

// a registry entry: axes from its flat/arrays.json, chunks from Icechunk
const reg = await openRegistry("data/fourd/stores.json");
const sst = await reg.open("oisst-sst");

// or any public Zarr or Icechunk store, described from its own metadata
const t2m = await openUrl("https://example.org/era5.zarr", "2m_temperature");

const w = sst.window({ lon: [100, 180], lat: [-70, -30] });
const v = await sst.get({ t: sst.timeAt("2024-03-01").index, ...w });

A registry entry may name a url (and var) instead of a path, and is then described from the store's own metadata; a projected CRS found there is used as the entry's crs.

Within allboa

• The shared axis description. A Source's description (above) is where allboa's design record for a shared description of a grid's axes starts: the record lines up ndr, mdim-refs (the flat/arrays.json this package reads) and wxy-domain against it, field by field. Changes to the description's shape go through that record in allboa/design.
• Time. scenespec takes a time axis with the browser-resolved layer (decision 0011, from 0010 item 3). The Source's clock (dates on t, timeAt()) is the working model for it.
• Reprojection. Every vertex here goes through proj4js, densified on the way (grids are meshed, lines are stepped), and drawn in the view's frame. allboa's gate probe found densified proj4js within 1 px of PROJ, which is the footing for drawing this way; the renderer contract is decision 0012.
• Views. scenespec's views (projected, cartesian, globe) and this package's frame (globe, azimuthal equidistant, Spilhaus, with unfold and depth) are to meet in the spec; mesh layers (scenespec 0.7) are the nearest shared ground.

Run

npm install
npm test
npm run serve   # then open http://localhost:8000/fourd.html

Next

Publish to npm and switch playproj to import the package. The 4D page's store explorer link points at store.html, which stays in playproj.