docs(changelog): add the #1705 fragment

Co-Authored-By: Claude Fable 5.2 <[email protected]>

changelog.d/1705-traffic-road-load.md

@@ -0,0 +1,4 @@
+- Cut the stutter while zooming and panning with Street Traffic on in dense
+  cities. Coarse roads are no longer clipped against every detail tile in one
+  task, roads already parsed in a load are not parsed again, and ground floors
+  are read once per cell (mazy1998, #1705).

changelog.d/1713-clouds-infrared-lut.md

@@ -1,3 +0,0 @@
-- Halve the time the satellite cloud image takes to prepare on the 3D Tiles
-  map by applying its transparency curve from a lookup table, in place
-  (mazy1998, #1713).

changelog.d/1721-clouds-infrared-shader.md

@@ -1,3 +0,0 @@
-- Satellite clouds on the 3D Tiles map apply their transparency in the shader
-  instead of rewriting each 4096 x 2048 image on the page, and changing the
-  cloud strength no longer builds a new image (mazy1998, #1721).

docs/CURRENT-STATE.md

@@ -891,11 +891,9 @@ image proxy accepts `bbox=west,south,east,north` for every product: inside the
 product bounds, 2:1 within 1 %, rounded to 0.25°, up to 4096×2048 (the
 default), cached by product, time, size and bbox. Diagnostics report
 `shell.detail` (`bbox`, `size`, `ready`, `enabled`).
-Clouds only applies a soft brightness ramp, using
+Clouds only applies a soft brightness ramp to decoded pixels once, using
 Cesium's sRGB-to-linear conversion (`channel ** 2.2`) and smoothstep from 0.40
-to 0.70. Globe hosts apply it to decoded pixels once; a shell applies the same
-ramp in its fragment shader from a strength uniform, so its images are drawn
-as decoded and a strength change neither fetches nor rewrites an image. The old 0.55 threshold is the ramp midpoint. RGB and source alpha are
+to 0.70. The old 0.55 threshold is the ramp midpoint. RGB and source alpha are
 preserved in Full image mode; both modes use the chosen layer opacity. This
 is a display filter, not a cloud mask. The cloud-filter slider is a continuous
 0–100% strength: 0% is Full, 100% is the existing Clouds only key, and
@@ -911,13 +909,13 @@ and processes it before staging. Globe hosts crop that canvas into 256 px tiles
 to maximum level 3 on a geographic 2×1 root grid bounded to the manifest extent,
 avoiding request-dependent contrast seams.
 On globe hosts, regional infrared retains network tiles and processes each
-decoded tile once; shells never read a frame's pixels back.
+decoded tile once; shells process each whole frame once.
 Exact-time tile and image responses are immutable for 24 hours; manifests and
 errors remain uncached. Each globe renderer retains up to 6 processed global
 mosaics in a least-recently-used cache keyed by observation time and infrared
 mode (up to 48 MiB of canvas pixels). Each shell keeps decoded full-extent and
 detail images in one least-recently-used cache bounded at 128 MiB, keyed by
-time and window: the shown frame and the warmed next frame, each
+time, mode and window: the shown frame and the warmed next frame, each
 full-extent and detail; nothing older survives them. Disable clears the caches.
 Cache hits skip
 fetch/decode and report `mosaic.cached: true` with zero decode time.

src/layers/traffic/flow.js

@@ -1,6 +1,7 @@
 import { roadIdentity } from './retention.js';
 import * as Cesium from 'cesium';
 import {
+  floorCellReader,
   prepareRoadSurfaces,
   roadHeightStations,
   trafficSurfaceReady,
@@ -301,6 +302,7 @@ export function createFlow({ state: layerState, services, parts, source }) {
       }
     }
     if (depthHeight !== undefined) layerState._viewHeightEstimate = depthHeight;
+    const floorAt = floorCellReader(services.ground);
     for (const road of roads) {
       road.key ||= roadIdentity(road);
       const prepared = !refining && preparedRoads.get(road.key);
@@ -319,7 +321,7 @@ export function createFlow({ state: layerState, services, parts, source }) {
         );
         for (let i = 0; i < road.coords.length; i++) {
           const [lon, lat] = road.coords[i];
-          const floor = services.ground?.cachedGroundFloor?.(lat, lon);
+          const floor = floorAt(lat, lon);
           const height =
             Number.isFinite(floor) && Math.abs(floor) <= 9000
               ? Math.max(floor, layerState._viewHeightEstimate)

src/layers/traffic/index.js

@@ -39,10 +39,10 @@ export function createTrafficLayer({ services, source }) {
   parts.controls = createControls(context);
   parts.lifecycle = createLifecycle(context);
   state._parseRoads = TRAFFIC_TIMING_ENABLED
-    ? (data, trace) =>
+    ? (data, trace, parsedBySource) =>
         trace
-          ? parts.timing.parseRoadsTimed(data, trace)
-          : parts.model.parseRoads(data)
+          ? parts.timing.parseRoadsTimed(data, trace, parsedBySource)
+          : parts.model.parseRoads(data, trace, parsedBySource)
     : parts.model.parseRoads;
 
   state._loadRoadsForBounds = TRAFFIC_TIMING_ENABLED

src/layers/traffic/ingestion.js

@@ -348,11 +348,16 @@ export function createIngestion({
     layerState._retainedPreview = false;
     layerState._detailRoadsReady = false;
     let paintRevision = 0;
+    // The snapshot that ends a pass replaces the streamed roads with the
+    // composed set, which is mostly the tile records already parsed and
+    // drawn. Remembering those per pass means only the records new to that
+    // snapshot (the clipped coarse roads) are parsed, not the whole set again.
+    let parsedBySource = new WeakMap();
     const onTile = (data, passSignal, preview) => {
       if (generation !== layerState._loadGeneration || passSignal.aborted)
         return;
       const start = performance.now();
-      const parsed = layerState._parseRoads(data, trace);
+      const parsed = layerState._parseRoads(data, trace, parsedBySource);
       phaseTiming('parse', start, { roads: parsed.length, incremental: true });
       if (data.replace) streamed = parsed;
       else streamed.push(...parsed);
@@ -531,6 +536,7 @@ export function createIngestion({
       if (altitude > FAST_FETCH_ALTITUDE) return;
 
       streamed = [];
+      parsedBySource = new WeakMap();
       majorPass = false;
       // Detailed pass: fetch the full road graph (tertiary, residential, etc.)
       console.log(`[Data:Traffic] Full fetch local roads [${cacheKey}]`);

src/layers/traffic/model.js

@@ -1,5 +1,5 @@
 import * as Cesium from 'cesium';
-import { roadSurfaceChunks } from './surface.js';
+import { floorCellReader, roadSurfaceChunks } from './surface.js';
 import { t, translateKnown } from '../../i18n/index.js';
 import {
   flowDensityMult,
@@ -13,22 +13,35 @@ import {
 } from './policy.js';
 
 export function createModel({ state: layerState, services, parts, source }) {
-  /** Build scene waypoints from source records; thinning and terrain remain rendering policy. */
-  function parseRoads(roadData) {
+  /**
+   * Build scene waypoints from source records; thinning and terrain remain rendering policy.
+   *
+   * `parsedBySource` (source record → its parsed roads) is filled as records
+   * are parsed, and a record already in it is answered from it.
+   */
+  function parseRoads(roadData, _trace, parsedBySource) {
     if (!roadData || !roadData.roads) {
       return [];
     }
 
     const roads = [];
+    const floorAt = floorCellReader(services.ground);
     for (const road of roadData.roads) {
       if (!road.coordinates || road.coordinates.length < 2) continue;
+      // A replacing snapshot repeats records this load already parsed.
+      const known = parsedBySource?.get(road);
+      if (known) {
+        for (const parsed of known) roads.push(parsed);
+        continue;
+      }
+      const first = roads.length;
 
       for (const coords of roadSurfaceChunks(road.coordinates)) {
         const type = road.type;
         const oneway = road.oneway;
         // Pre-compute Cartesian3 waypoints (lon, lat, height) for fast lerp animation
         const waypoints = coords.map(([lng, lat]) => {
-          const floor = services.ground?.cachedGroundFloor?.(lat, lng);
+          const floor = floorAt(lat, lng);
           const h =
             (Number.isFinite(floor) && Math.abs(floor) <= 9000
               ? floor
@@ -60,6 +73,7 @@ export function createModel({ state: layerState, services, parts, source }) {
             flow: road.flow || null,
           });
       }
+      parsedBySource?.set(road, roads.slice(first));
     }
 
     return roads;

src/layers/traffic/roadLoadCost.test.mjs

@@ -0,0 +1,444 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import * as Cesium from 'cesium';
+import { createTrafficSource, outsideDetailTiles } from './source.js';
+import { createIngestion } from './ingestion.js';
+import { createModel } from './model.js';
+import { floorCellReader, roadSurfaceChunks } from './surface.js';
+import { DOT_HEIGHT_OFFSET } from './policy.js';
+import { clipTileLine } from '../../sources/openFreeMap.js';
+import { tileToBBox } from '../../data/tomtomTiles.js';
+
+// The clip as it was before the extent shortcut: every road against the four
+// regions around every tile. The shortcut must return exactly this.
+function clipEveryRoadAgainstEveryTile(roads, tiles) {
+  return roads.flatMap((road) => {
+    let lines = [road.coordinates];
+    for (const tile of tiles) {
+      const box = tileToBBox(tile.z, tile.x, tile.y);
+      const regions = [
+        { west: -180, east: box.west, south: -85, north: 85 },
+        { west: box.east, east: 180, south: -85, north: 85 },
+        { west: box.west, east: box.east, south: -85, north: box.south },
+        { west: box.west, east: box.east, south: box.north, north: 85 },
+      ];
+      lines = lines.flatMap((line) =>
+        regions.flatMap((region) => clipTileLine(line, region)),
+      );
+    }
+    return lines.map((coordinates) => ({ ...road, coordinates }));
+  });
+}
+
+function seeded(seed) {
+  let state = seed >>> 0;
+  return () => {
+    state = (Math.imul(state, 1664525) + 1013904223) >>> 0;
+    return state / 2 ** 32;
+  };
+}
+
+function tileBlock(x, y, size = 4) {
+  const tiles = [];
+  for (let dx = 0; dx < size; dx++)
+    for (let dy = 0; dy < size; dy++)
+      tiles.push({ z: 14, x: x + dx, y: y + dy });
+  return tiles;
+}
+
+/** Roads in and around a tile block: wandering, straight, tiny, and on tile edges. */
+function roadsAround(tiles, random, count = 400) {
+  const boxes = tiles.map((tile) => tileToBBox(tile.z, tile.x, tile.y));
+  const west = Math.min(...boxes.map((box) => box.west)),
+    east = Math.max(...boxes.map((box) => box.east)),
+    south = Math.min(...boxes.map((box) => box.south)),
+    north = Math.max(...boxes.map((box) => box.north));
+  const width = east - west,
+    height = north - south;
+  const roads = [];
+  for (let i = 0; i < count; i++) {
+    const step = i % 7 === 0 ? 0.00002 : i % 3 === 0 ? 0.01 : 0.002;
+    let lon = west - width / 2 + random() * width * 2,
+      lat = south - height / 2 + random() * height * 2;
+    const coordinates = [[lon, lat]];
+    const points = 1 + Math.floor(random() * 12);
+    for (let j = 0; j < points; j++) {
+      lon += (random() - 0.5) * step;
+      lat += (random() - 0.5) * step;
+      coordinates.push([lon, lat]);
+    }
+    roads.push({ type: 'primary', oneway: i % 2, id: i, coordinates });
+  }
+  const box = boxes[5];
+  const midLat = (box.south + box.north) / 2,
+    midLon = (box.west + box.east) / 2;
+  roads.push(
+    // Along a tile edge, ending on a corner, and touching an edge from outside.
+    {
+      id: 'edge',
+      coordinates: [
+        [box.west, box.south - 0.01],
+        [box.west, box.north + 0.01],
+      ],
+    },
+    {
+      id: 'corner',
+      coordinates: [
+        [box.west - 0.01, box.south - 0.01],
+        [box.west, box.south],
+        [box.east, box.north],
+      ],
+    },
+    {
+      id: 'touch',
+      coordinates: [
+        [box.west - 0.01, midLat],
+        [box.west, midLat],
+      ],
+    },
+    // Across the whole block, and a repeated vertex.
+    {
+      id: 'across',
+      coordinates: [
+        [west - 0.01, midLat],
+        [east + 0.01, midLat + 0.0003],
+      ],
+    },
+    {
+      id: 'repeat',
+      coordinates: [
+        [midLon, midLat],
+        [midLon, midLat],
+        [midLon + 0.001, midLat],
+      ],
+    },
+    // Records the clip drops or leaves alone.
+    { id: 'single', coordinates: [[west - 0.02, midLat]] },
+    { id: 'empty', coordinates: [] },
+    {
+      id: 'negative-zero',
+      coordinates: [
+        [-0, south - 0.02],
+        [0.001, south - 0.02],
+      ],
+    },
+    {
+      id: 'polar',
+      coordinates: [
+        [west - 0.02, 86],
+        [west - 0.02, 86.01],
+      ],
+    },
+  );
+  return roads;
+}
+
+for (const [place, x, y] of [
+  ['Manhattan', 4823, 6158],
+  ['London, across longitude 0', 8190, 5446],
+  ['longitude 0 and latitude 0', 8190, 8190],
+  ['the southern and eastern hemispheres', 15070, 9826],
+])
+  test(`coarse roads clipped around detail tiles match the every-tile clip: ${place}`, () => {
+    const tiles = tileBlock(x, y);
+    const roads = roadsAround(tiles, seeded(x * 31 + y));
+    for (const loaded of [tiles, tiles.slice(0, 5), tiles.slice(3, 4), []]) {
+      const expected = clipEveryRoadAgainstEveryTile(roads, loaded);
+      assert.ok(loaded.length === 0 || expected.length !== roads.length);
+      // deepStrictEqual separates -0 from 0 and compares every vertex exactly.
+      assert.deepStrictEqual(outsideDetailTiles(roads, loaded), expected);
+    }
+  });
+
+test('only a road that reaches a detail tile is clipped against it', () => {
+  const tiles = tileBlock(4823, 6158);
+  const block = tiles.map((tile) => tileToBBox(tile.z, tile.x, tile.y));
+  const west = Math.min(...block.map((box) => box.west)),
+    north = Math.max(...block.map((box) => box.north));
+  // 300 roads beside the block and between its tile edges, none touching one.
+  const clear = [];
+  for (let i = 0; i < 300; i++) {
+    const box = block[i % block.length];
+    const lon = i % 2 ? west - 0.02 - i * 1e-5 : box.west + 0.004;
+    const lat = i % 2 ? box.south + 0.004 : north + 0.01 + i * 1e-5;
+    clear.push({
+      coordinates: [
+        [lon, lat],
+        [lon + 0.002, lat + 0.0005],
+        [lon + 0.003, lat + 0.001],
+      ],
+    });
+  }
+  const first = block[0];
+  const crossing = {
+    coordinates: [
+      [first.west + 0.004, north + 0.01],
+      [first.west + 0.004, (first.south + first.north) / 2],
+    ],
+  };
+  let clips = 0;
+  const counted = (line, region) => {
+    clips++;
+    return clipTileLine(line, region);
+  };
+  const roads = outsideDetailTiles([...clear, crossing], tiles, counted);
+  assert.deepStrictEqual(
+    roads,
+    clipEveryRoadAgainstEveryTile([...clear, crossing], tiles),
+  );
+  assert.equal(roads.length, 301);
+  // Four regions for each tile the crossing road reaches, never the 19,264
+  // clips of every road against every tile.
+  assert.ok(clips >= 4, `expected the crossing road to be clipped: ${clips}`);
+  assert.ok(clips <= 4 * tiles.length, `clipped ${clips} times`);
+});
+
+/** A DEM-regime ground service: one floor per toFixed(3) cell, counting reads. */
+function cellGround({ mesh = false, warm = () => true } = {}) {
+  const ground = {
+    reads: 0,
+    meshFloorPreferred: () => mesh,
+    cachedGroundFloor(lat, lon) {
+      ground.reads++;
+      if (!Number.isFinite(lat) || !Number.isFinite(lon)) return null;
+      // Number() as the shared cache does it: "-0.000" and "0.000" are one cell.
+      const cell = `${Number(lat.toFixed(3))},${Number(lon.toFixed(3))}`;
+      if (!warm(cell)) return null;
+      let hash = 0;
+      for (const character of cell)
+        hash = (Math.imul(hash, 31) + character.charCodeAt(0)) | 0;
+      // The mesh regime answers per point, not per cell.
+      return (hash % 4000) / 10 + (mesh ? lat - Math.floor(lat * 1000) / 1000 : 0);
+    },
+  };
+  return ground;
+}
+
+test('floor reads are shared per cell and equal the per-coordinate reads', () => {
+  const random = seeded(7);
+  const points = [];
+  for (let i = 0; i < 4000; i++)
+    points.push([40.75 + random() * 0.01, -73.99 + random() * 0.01]);
+  // Cell edges, where toFixed(3) and Math.round can disagree, in each sign.
+  for (const lat of [40.7505, -40.7505, 0.0005, -0.0005, 1.0005, 8.5745])
+    for (const lon of [-73.9905, 73.9905, 0.0005, -0.0005, 1.0005, 2.3515])
+      points.push([lat, lon], [lat + 1e-9, lon - 1e-9], [lat - 1e-9, lon]);
+  points.push([Number.NaN, 0], [0, Infinity], [0, 0], [-0, -0]);
+
+  const direct = cellGround();
+  const expected = points.map(([lat, lon]) =>
+    direct.cachedGroundFloor(lat, lon),
+  );
+  const ground = cellGround();
+  const floorAt = floorCellReader(ground);
+  assert.deepStrictEqual(
+    points.map(([lat, lon]) => floorAt(lat, lon)),
+    expected,
+  );
+  // 4000 points in a 0.01 degree square share about 121 cells.
+  assert.ok(ground.reads < 600, `read the shared cache ${ground.reads} times`);
+
+  // A cold cell is remembered as cold for the pass, not asked again.
+  const cold = cellGround({ warm: () => false });
+  const coldAt = floorCellReader(cold);
+  assert.equal(coldAt(40.7512, -73.9812), null);
+  assert.equal(coldAt(40.7513, -73.9813), null);
+  assert.equal(cold.reads, 1);
+});
+
+test('mesh floors and unknown ground services are read per coordinate', () => {
+  const mesh = cellGround({ mesh: true });
+  const meshAt = floorCellReader(mesh);
+  const a = meshAt(40.7512, -73.9812),
+    b = meshAt(40.75121, -73.9812);
+  assert.equal(mesh.reads, 2);
+  assert.notEqual(a, b);
+
+  // No regime to ask: nothing says a floor is the same across a cell.
+  let reads = 0;
+  const bareAt = floorCellReader({ cachedGroundFloor: () => ++reads });
+  bareAt(40.7512, -73.9812);
+  bareAt(40.7512, -73.9812);
+  assert.equal(reads, 2);
+  assert.equal(floorCellReader(undefined)(1, 2), undefined);
+  assert.equal(floorCellReader({})(1, 2), undefined);
+});
+
+function road(lon, lat, points = 40) {
+  const coordinates = [];
+  for (let i = 0; i < points; i++)
+    coordinates.push([lon + i * 0.00004, lat + i * 0.00003]);
+  return { type: 'residential', oneway: 1, coordinates };
+}
+
+test('parsing reads each floor cell once and builds the same waypoints', () => {
+  const ground = cellGround({ warm: (cell) => !cell.endsWith('3') });
+  const state = { _viewHeightEstimate: 12 };
+  const model = createModel({
+    state,
+    services: { ground },
+    parts: {},
+    source: {},
+  });
+  const records = [road(-73.99, 40.75), road(-73.9899, 40.7501)];
+  const parsed = model.parseRoads({ roads: records });
+  const coordinates = records.reduce(
+    (count, record) => count + record.coordinates.length,
+    0,
+  );
+  assert.ok(
+    ground.reads < coordinates / 3,
+    `${ground.reads} floor reads for ${coordinates} coordinates`,
+  );
+
+  const direct = cellGround({ warm: (cell) => !cell.endsWith('3') });
+  const expected = records.flatMap((record) =>
+    roadSurfaceChunks(record.coordinates).map((coords) =>
+      coords.map(([lon, lat]) => {
+        const floor = direct.cachedGroundFloor(lat, lon);
+        return Cesium.Cartesian3.fromDegrees(
+          lon,
+          lat,
+          (floor ?? state._viewHeightEstimate) + DOT_HEIGHT_OFFSET,
+        );
+      }),
+    ),
+  );
+  assert.ok(direct.reads >= coordinates);
+  assert.deepStrictEqual(
+    parsed.map((entry) => entry.waypoints),
+    expected,
+  );
+});
+
+test('a record parsed earlier in the pass is not parsed again', () => {
+  const ground = cellGround();
+  const model = createModel({
+    state: {},
+    services: { ground },
+    parts: {},
+    source: {},
+  });
+  const first = { ...road(-73.99, 40.75), oneway: 0 },
+    second = road(-73.98, 40.76),
+    short = { type: 'primary', coordinates: [[-73.97, 40.77]] };
+  const parsedBySource = new WeakMap();
+  const tile = model.parseRoads({ roads: [first] }, null, parsedBySource);
+  assert.equal(tile.length, 2, 'a two-way record parses to both directions');
+  const reads = ground.reads;
+  const replaced = model.parseRoads(
+    { roads: [second, short, first], replace: true },
+    null,
+    parsedBySource,
+  );
+  assert.equal(replaced.length, 3);
+  // The same parsed roads, in the snapshot's order: dots stay attached.
+  assert.equal(replaced[1], tile[0]);
+  assert.equal(replaced[2], tile[1]);
+  const fresh = cellGround();
+  createModel({
+    state: {},
+    services: { ground: fresh },
+    parts: {},
+    source: {},
+  }).parseRoads({ roads: [second] });
+  assert.equal(ground.reads - reads, fresh.reads, 'only the new record read');
+
+  // Without the map every call parses, as before.
+  const again = model.parseRoads({ roads: [first] });
+  assert.notEqual(again[0], tile[0]);
+  assert.deepStrictEqual(again, tile);
+});
+
+test('the snapshot that ends a pass parses only the records it adds', async () => {
+  const detail = { z: 14, x: 3743, y: 6745 };
+  const core = tileToBBox(detail.z, detail.x, detail.y);
+  const local = {
+    type: 'residential',
+    oneway: 1,
+    coordinates: [
+      [core.west + 0.002, core.south + 0.002],
+      [core.west + 0.004, core.south + 0.004],
+    ],
+  };
+  const distant = {
+    type: 'primary',
+    oneway: 1,
+    coordinates: [
+      [core.east + 0.01, core.south],
+      [core.east + 0.02, core.south],
+    ],
+  };
+  const bounds = {
+    ...core,
+    east: core.east + 0.03,
+    coverage: {
+      detail: [detail],
+      coarse: [{ z: 12, x: 935, y: 1686 }],
+      key: 'test',
+    },
+  };
+  const source = createTrafficSource({
+    mapTiles: {
+      async fetchBounds(box, { zoom, onTile }) {
+        const tile = { roads: zoom === 14 ? [local] : [distant] };
+        onTile?.(tile);
+        return {
+          tiles: [tile],
+          loadedTiles: zoom === 14 ? [detail] : bounds.coverage.coarse,
+          partial: false,
+        };
+      },
+    },
+  });
+  const parsedRecords = [];
+  const painted = [];
+  const state = {
+    _enabled: true,
+    _loadGeneration: 0,
+    _tileCache: new Map(),
+    _roadMode: null,
+    _liveMode: false,
+    // The model's contract: fill the map, answer known records from it.
+    _parseRoads: (data, trace, parsedBySource) =>
+      data.roads.flatMap((record) => {
+        const known = parsedBySource?.get(record);
+        if (known) return known;
+        parsedRecords.push(record);
+        const parsed = [{ record }];
+        parsedBySource?.set(record, parsed);
+        return parsed;
+      }),
+  };
+  const ingestion = createIngestion({
+    state,
+    source,
+    services: {},
+    parts: {
+      viewport: {
+        clampBounds: (b) => b,
+        getBoundsCenter: () => ({ lat: 30.26, lon: -97.74 }),
+      },
+      flow: {
+        warmFlow: () => Promise.resolve([]),
+        applyFlowThenRender: async (roads, box, generation, altitude, label) => {
+          if (label === 'Loaded full') painted.push(roads);
+          return true;
+        },
+      },
+    },
+  });
+  await ingestion.loadRoadsForBounds(bounds, 350);
+  assert.equal(
+    parsedRecords.filter((record) => record === local).length,
+    1,
+    'the detail tile record is parsed when its tile streams, not again',
+  );
+  // The full graph is still the detail record plus the coarse road outside it.
+  assert.equal(painted.at(-1).length, 2);
+  assert.equal(painted.at(-1)[0].record, local);
+  assert.deepStrictEqual(
+    painted.at(-1)[1].record.coordinates,
+    distant.coordinates,
+  );
+});

src/layers/traffic/source.js

@@ -33,23 +33,108 @@ export function trafficDetailBounds(box) {
   return detail;
 }
 
-/** Keep coarse roads only outside the detailed tile cores. */
-export function outsideDetailTiles(roads, tiles) {
+/** Longitude/latitude extent of one line; NaN coordinates leave it unusable. */
+function lineExtent(coordinates) {
+  let west = Infinity,
+    east = -Infinity,
+    south = Infinity,
+    north = -Infinity;
+  for (const [lon, lat] of coordinates) {
+    if (!(lon >= west)) west = lon;
+    if (!(lon <= east)) east = lon;
+    if (!(lat >= south)) south = lat;
+    if (!(lat <= north)) north = lat;
+  }
+  return { coordinates, west, east, south, north, settled: false };
+}
+
+/**
+ * What `clipTileLine` returns for a line lying wholly inside the clip region:
+ * the same line with each vertex recomputed from the one before it. Returns
+ * null for a line under the 12 m floor `clipTileLine` drops.
+ */
+function unclippedLine(coordinates) {
+  if (coordinates.length < 2) return null;
+  const out = [];
+  let metres = 0;
+  for (let i = 1; i < coordinates.length; i++) {
+    const a = coordinates[i - 1],
+      b = coordinates[i];
+    const dx = b[0] - a[0],
+      dy = b[1] - a[1];
+    if (i === 1) out.push([a[0] + 0 * dx, a[1] + 0 * dy]);
+    out.push([a[0] + dx, a[1] + dy]);
+    metres +=
+      Math.hypot(
+        (out[i][0] - out[i - 1][0]) * Math.cos((out[i][1] * Math.PI) / 180),
+        out[i][1] - out[i - 1][1],
+      ) * 111320;
+  }
+  return metres >= 12 ? out : null;
+}
+
+const sameLine = (a, b) =>
+  a.every(
+    (point, i) => Object.is(point[0], b[i][0]) && Object.is(point[1], b[i][1]),
+  );
+
+/**
+ * Keep coarse roads only outside the detailed tile cores.
+ *
+ * Each tile splits a line into the four regions around its core. Nearly every
+ * coarse road lies wholly inside one of those regions for nearly every tile,
+ * where the clip hands the line back unchanged, so that case is answered from
+ * the line's extent and only a line that reaches a tile's core or edge is
+ * clipped. Clipping every road against every tile froze the page for hundreds
+ * of milliseconds per road load at street level.
+ *
+ * `clip` is injectable for tests.
+ */
+export function outsideDetailTiles(roads, tiles, clip = clipTileLine) {
+  const boxes = tiles.map((tile) => tileToBBox(tile.z, tile.x, tile.y));
   return roads.flatMap((road) => {
-    let lines = [road.coordinates];
-    for (const tile of tiles) {
-      const box = tileToBBox(tile.z, tile.x, tile.y);
-      const regions = [
-        { west: -180, east: box.west, south: -85, north: 85 },
-        { west: box.east, east: 180, south: -85, north: 85 },
-        { west: box.west, east: box.east, south: -85, north: box.south },
-        { west: box.west, east: box.east, south: box.north, north: 85 },
-      ];
-      lines = lines.flatMap((line) =>
-        regions.flatMap((region) => clipTileLine(line, region)),
-      );
+    let lines = [lineExtent(road.coordinates)];
+    for (const box of boxes) {
+      const next = [];
+      for (const line of lines) {
+        // Strictly inside one region, and inside the bounds every region
+        // shares: the other three regions return nothing.
+        const clear =
+          line.west > -180 &&
+          line.east < 180 &&
+          line.south > -85 &&
+          line.north < 85 &&
+          (line.east < box.west ||
+            line.west > box.east ||
+            (line.west > box.west &&
+              line.east < box.east &&
+              (line.north < box.south || line.south > box.north)));
+        if (!clear) {
+          const regions = [
+            { west: -180, east: box.west, south: -85, north: 85 },
+            { west: box.east, east: 180, south: -85, north: 85 },
+            { west: box.west, east: box.east, south: -85, north: box.south },
+            { west: box.west, east: box.east, south: box.north, north: 85 },
+          ];
+          for (const region of regions)
+            for (const coordinates of clip(line.coordinates, region))
+              next.push(lineExtent(coordinates));
+        } else if (line.settled) {
+          next.push(line);
+        } else {
+          // The first unclipped pass can still move a vertex by a rounding
+          // step (a road crossing longitude or latitude 0); once a pass
+          // changes nothing, no later one will.
+          const coordinates = unclippedLine(line.coordinates);
+          if (!coordinates) continue;
+          const kept = lineExtent(coordinates);
+          kept.settled = sameLine(coordinates, line.coordinates);
+          next.push(kept);
+        }
+      }
+      lines = next;
     }
-    return lines.map((coordinates) => ({ ...road, coordinates }));
+    return lines.map(({ coordinates }) => ({ ...road, coordinates }));
   });
 }
 

src/layers/traffic/surface.js

@@ -69,6 +69,45 @@ export function trafficSurfaceReady(scene) {
   return currentRenderedFrame(scene)?.ready === true;
 }
 
+/**
+ * Ground-floor reads for one synchronous pass over road coordinates, asking
+ * the shared cache once per floor cell instead of once per coordinate.
+ *
+ * A road tile puts thousands of coordinates into a few hundred ~111 m cells,
+ * and each shared read formats and looks up two string keys, which added up
+ * to seconds per street-level load. Mesh floors answer per point (the nearest
+ * reading in the cell), so they are read through unchanged; only the DEM
+ * regime is one value per cell. Build a reader per pass: cells warm up
+ * between passes.
+ */
+export function floorCellReader(ground) {
+  const read = ground?.cachedGroundFloor;
+  if (!read) return () => undefined;
+  if (ground.meshFloorPreferred?.() !== false)
+    return (lat, lon) => read(lat, lon);
+  const cells = new Map();
+  return (lat, lon) => {
+    const y = lat * 1000,
+      x = lon * 1000;
+    const row = Math.round(y),
+      column = Math.round(x);
+    // The shared cache rounds with toFixed(3). At a cell edge that and
+    // Math.round can pick different cells, so an edge point asks directly.
+    if (!(
+      Math.abs(Math.abs(y - row) - 0.5) > 1e-6 &&
+      Math.abs(Math.abs(x - column) - 0.5) > 1e-6
+    ))
+      return read(lat, lon);
+    const key = row * 1e6 + column;
+    let floor = cells.get(key);
+    if (floor === undefined) {
+      floor = read(lat, lon) ?? null;
+      cells.set(key, floor);
+    }
+    return floor;
+  };
+}
+
 /** Preserve bends and insert height samples at most 150 m apart, splitting long roads. */
 export function roadSurfaceChunks(coordinates) {
   const chunks = [];

src/layers/traffic/timing.js

@@ -1,5 +1,5 @@
 import * as Cesium from 'cesium';
-import { roadSurfaceChunks } from './surface.js';
+import { floorCellReader, roadSurfaceChunks } from './surface.js';
 import { TRAFFIC_TIMING_ENABLED, DOT_HEIGHT_OFFSET } from './policy.js';
 
 export function createTiming({ state: layerState, services, parts, source }) {
@@ -190,7 +190,7 @@ export function createTiming({ state: layerState, services, parts, source }) {
    * waypoint-materialization time independently.
    */
 
-  function parseRoadsTimed(roadData, trace) {
+  function parseRoadsTimed(roadData, trace, parsedBySource) {
     /* TRACE_ONLY_BEGIN */
     const _trafficTimingState = trafficTimingPass(
       trace,
@@ -231,11 +231,19 @@ export function createTiming({ state: layerState, services, parts, source }) {
     }
 
     const roads = [];
+    const floorAt = floorCellReader(services.ground);
     /* TRACE_ONLY_BEGIN */
     let _trafficTimingWaypointMaterializationMs = 0;
     /* TRACE_ONLY_END */
     for (const road of roadData.roads) {
       if (!road.coordinates || road.coordinates.length < 2) continue;
+      // A replacing snapshot repeats records this load already parsed.
+      const known = parsedBySource?.get(road);
+      if (known) {
+        for (const parsed of known) roads.push(parsed);
+        continue;
+      }
+      const first = roads.length;
 
       for (const coords of roadSurfaceChunks(road.coordinates)) {
         const type = road.type;
@@ -245,7 +253,7 @@ export function createTiming({ state: layerState, services, parts, source }) {
         const _trafficTimingMaterializeStart = performance.now();
         /* TRACE_ONLY_END */
         const waypoints = coords.map(([lng, lat]) => {
-          const floor = services.ground?.cachedGroundFloor?.(lat, lng);
+          const floor = floorAt(lat, lng);
           const h =
             (Number.isFinite(floor) && Math.abs(floor) <= 9000
               ? floor
@@ -279,6 +287,7 @@ export function createTiming({ state: layerState, services, parts, source }) {
             flow: road.flow || null,
           });
       }
+      parsedBySource?.set(road, roads.slice(first));
     }
     /* TRACE_ONLY_BEGIN */
     const _trafficTimingMetrics = {

src/layers/weather/infraredAlpha.js

@@ -1,31 +1,22 @@
 export const INFRARED_ALPHA_T0 = 0.4;
 export const INFRARED_ALPHA_T1 = 0.7;
 
-/** How much of the cloud key applies, 0–1, for a display mode or a 0–100
- * strength. The weather shell passes it to its fragment shader. */
-export function infraredAmount(strength) {
-  return strength === 'full'
-    ? 0
-    : strength === 'filtered' || !Number.isFinite(strength)
-      ? 1
-      : Math.max(0, Math.min(100, strength)) / 100;
-}
-
-/** Scale each pixel's alpha in place; RGB is left as it is. The scale depends
- * only on the brightest channel, so it is worked out once for each of the 256
- * byte values instead of once per pixel: a 4096×2048 image has 8.4 million
- * pixels and the power curve per pixel held the page for over 100 ms. The
- * table holds the same numbers the per-pixel formula produced, so the output
- * bytes are unchanged.
+/** Return display pixels without changing RGB or the source RGBA bytes.
  * `strength` is 0–100: zero is the full image and 100 is the cloud key.
  */
-export function applyInfraredAlpha(pixels, strength = 'filtered') {
-  const amount = infraredAmount(strength);
+export function infraredAlpha(rgba, strength = 'filtered') {
+  const pixels = new Uint8ClampedArray(rgba);
+  const amount =
+    strength === 'full'
+      ? 0
+      : strength === 'filtered' || !Number.isFinite(strength)
+        ? 1
+        : Math.max(0, Math.min(100, strength)) / 100;
   if (amount === 0) return pixels;
-  const scale = new Float64Array(256);
-  for (let value = 0; value < 256; value++) {
+  for (let i = 0; i < pixels.length; i += 4) {
     // Match Cesium's czm_srgbToLinear conversion in draped imagery.
-    const linearMax = (value / 255) ** 2.2;
+    const linearMax =
+      (Math.max(rgba[i], rgba[i + 1], rgba[i + 2]) / 255) ** 2.2;
     const t = Math.max(
       0,
       Math.min(
@@ -35,21 +26,7 @@ export function applyInfraredAlpha(pixels, strength = 'filtered') {
       ),
     );
     const filtered = t * t * (3 - 2 * t);
-    scale[value] = 1 - amount + filtered * amount;
-  }
-  for (let i = 0; i < pixels.length; i += 4) {
-    const r = pixels[i];
-    const g = pixels[i + 1];
-    const b = pixels[i + 2];
-    const max = r > g ? (r > b ? r : b) : g > b ? g : b;
-    pixels[i + 3] = pixels[i + 3] * scale[max];
+    pixels[i + 3] = rgba[i + 3] * (1 - amount + filtered * amount);
   }
   return pixels;
 }
-
-/** Return display pixels without changing RGB or the source RGBA bytes.
- * `strength` is 0–100: zero is the full image and 100 is the cloud key.
- */
-export function infraredAlpha(rgba, strength = 'filtered') {
-  return applyInfraredAlpha(new Uint8ClampedArray(rgba), strength);
-}

src/layers/weather/infraredAlpha.test.mjs

@@ -1,7 +1,6 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import {
-  applyInfraredAlpha,
   infraredAlpha,
   INFRARED_ALPHA_T0,
   INFRARED_ALPHA_T1,
@@ -62,43 +61,3 @@ test('full infrared preserves every channel including partial and zero alpha', (
   ]);
   assert.deepEqual(infraredAlpha(pixels, 'full'), pixels);
 });
-
-test('the lookup table gives the per-pixel curve byte for byte, in place', () => {
-  // The transfer as it was written per pixel, before the table.
-  const perPixel = (rgba, amount) => {
-    const out = new Uint8ClampedArray(rgba);
-    for (let i = 0; i < out.length; i += 4) {
-      const linearMax =
-        (Math.max(rgba[i], rgba[i + 1], rgba[i + 2]) / 255) ** 2.2;
-      const t = Math.max(
-        0,
-        Math.min(
-          1,
-          (linearMax - INFRARED_ALPHA_T0) /
-            (INFRARED_ALPHA_T1 - INFRARED_ALPHA_T0),
-        ),
-      );
-      out[i + 3] = rgba[i + 3] * (1 - amount + t * t * (3 - 2 * t) * amount);
-    }
-    return out;
-  };
-  // Every brightest-channel value in each channel, against a spread of alphas.
-  const bytes = [];
-  for (let value = 0; value < 256; value++)
-    for (const alpha of [0, 1, 37, 128, 200, 254, 255]) {
-      bytes.push(value, 0, 0, alpha);
-      bytes.push(value >> 1, value, 0, alpha);
-      bytes.push(0, value >> 2, value, alpha);
-    }
-  const source = new Uint8ClampedArray(bytes);
-  for (const strength of [1, 33, 50, 99, 100, 'filtered', Number.NaN]) {
-    const amount = Number.isFinite(strength) ? strength / 100 : 1;
-    const pixels = source.slice();
-    assert.equal(applyInfraredAlpha(pixels, strength), pixels);
-    assert.deepEqual(pixels, perPixel(source, amount), `strength ${strength}`);
-  }
-  for (const strength of [0, 'full']) {
-    const pixels = source.slice();
-    assert.deepEqual(applyInfraredAlpha(pixels, strength), source);
-  }
-});

src/layers/weather/infraredImage.js

@@ -6,7 +6,7 @@ import {
   drawWeatherPixels,
   closeWeatherPixels,
 } from './source.js';
-import { applyInfraredAlpha } from './infraredAlpha.js';
+import { infraredAlpha } from './infraredAlpha.js';
 
 export const MAX_MOSAIC_BYTES = 4 * 1024 * 1024;
 
@@ -31,22 +31,13 @@ export function processInfraredImage(
 
 function applyInfraredTransfer(context, canvas, mode) {
   const pixels = context.getImageData(0, 0, canvas.width, canvas.height);
-  // In place: a copy of a 4096×2048 image is 33 MB, made and written back.
-  applyInfraredAlpha(pixels.data, mode);
+  pixels.data.set(infraredAlpha(pixels.data, mode));
   context.putImageData(pixels, 0, 0);
 }
 
 /** Draw pixels a frame source supplied into a new canvas, with the display
  * transfer for infrared products, and release them. They must be `size`. */
-function drawSuppliedImage(
-  pixels,
-  product,
-  mode,
-  size,
-  signal,
-  createCanvas,
-  transfer,
-) {
+function drawSuppliedImage(pixels, product, mode, size, signal, createCanvas) {
   try {
     signal.throwIfAborted();
     const { width, height } = weatherPixelSize(pixels);
@@ -57,7 +48,7 @@ function drawSuppliedImage(
     texture.height = height;
     const context = texture.getContext('2d');
     drawWeatherPixels(context, pixels);
-    if (transfer && (product === 'clouds' || product === 'clouds-regional'))
+    if (product === 'clouds' || product === 'clouds-regional')
       applyInfraredTransfer(context, texture, mode);
     return texture;
   } finally {
@@ -97,8 +88,7 @@ export function decodeInfraredImage(blob, signal) {
 }
 
 /** Fetch one capped whole-extent frame, or a `bbox` detail window of it, and draw
- * it into a canvas. Infrared frames get the display transfer unless `transfer`
- * is false, for a caller that applies it when drawing; a canvas also keeps
+ * it into a canvas. Infrared frames get the display transfer; a canvas also keeps
  * Cesium's texture row order, which an ImageBitmap upload would not. The decoded
  * image is always released. With a `frameSource` that has `getImage`, the host
  * supplies the decoded pixels instead and nothing is fetched or decoded here. */
@@ -117,7 +107,6 @@ export async function acquireWeatherImage(
     now = () => performance.now(),
     onFetched = () => {},
     frameSource = null,
-    transfer = true,
   },
 ) {
   if (frameSource?.getImage) {
@@ -138,7 +127,6 @@ export async function acquireWeatherImage(
       size,
       signal,
       createCanvas,
-      transfer,
     );
     return { texture, decodeMs: now() - started };
   }
@@ -159,7 +147,7 @@ export async function acquireWeatherImage(
     if (image.width !== size.width || image.height !== size.height)
       throw new Error('Invalid weather image dimensions');
     let texture;
-    if (transfer && (product === 'clouds' || product === 'clouds-regional'))
+    if (product === 'clouds' || product === 'clouds-regional')
       texture = processInfraredImage(image, mode, createCanvas);
     else {
       texture = createCanvas();

src/layers/weather/infraredImage.test.mjs

@@ -26,75 +26,6 @@ function canvas() {
   return output;
 }
 
-test('the transfer is applied to the canvas pixels in place, with no copy written back', () => {
-  let read = null;
-  const output = {};
-  output.getContext = () => ({
-    drawImage() {},
-    getImageData: () => {
-      read = { data: new Uint8ClampedArray([194, 0, 0, 200]) };
-      // A second full-size buffer copied over the first is what this guards.
-      read.data.set = () => {
-        throw new Error('the canvas pixels were overwritten from a copy');
-      };
-      return read;
-    },
-    putImageData: (pixels) => {
-      output.pixels = pixels;
-    },
-  });
-  processInfraredImage({ width: 1, height: 1 }, 'filtered', () => output);
-  assert.equal(output.pixels, read);
-  assert.deepEqual([...read.data], [194, 0, 0, 98]);
-});
-
-test('with transfer off an infrared frame is drawn and never read back', async () => {
-  const drawn = [];
-  const createCanvas = () => {
-    const output = {};
-    output.getContext = () => ({
-      drawImage: (image) => drawn.push(image),
-      getImageData: () => {
-        throw new Error('the frame was read back on the page');
-      },
-      putImageData: () => {
-        throw new Error('the frame was rewritten on the page');
-      },
-    });
-    return output;
-  };
-  const size = { width: 4096, height: 2048 };
-  const image = { ...size, close() {} };
-  const options = {
-    signal: new AbortController().signal,
-    mode: 'filtered',
-    size,
-    maxBytes: 1024,
-    createCanvas,
-    transfer: false,
-  };
-  const fetched = await acquireWeatherImage(
-    'clouds-regional',
-    '2026-09-15T20:00:00.000Z',
-    {
-      ...options,
-      fetchImpl: async () => ({
-        ok: true,
-        headers: new Headers(),
-        arrayBuffer: async () => new ArrayBuffer(1),
-      }),
-      decodeImage: async () => image,
-    },
-  );
-  assert.equal(fetched.texture.width, 4096);
-  const supplied = { ...size };
-  await acquireWeatherImage('clouds-regional', '2026-09-15T20:00:00.000Z', {
-    ...options,
-    frameSource: { getImage: async () => supplied },
-  });
-  assert.deepEqual(drawn, [image, supplied]);
-});
-
 test('decoded pixels are processed once on a same-sized canvas', () => {
   const image = { width: 1, height: 1 };
   const output = processInfraredImage(image, 'filtered', canvas);

src/layers/weather/shellRendering.js

@@ -1,9 +1,4 @@
 import { acquireWeatherImage } from './infraredImage.js';
-import {
-  INFRARED_ALPHA_T0,
-  INFRARED_ALPHA_T1,
-  infraredAmount,
-} from './infraredAlpha.js';
 import { imageryHostStatus } from './imageryHost.js';
 import { WEATHER_DETAIL_SIZE, WEATHER_IMAGE_SIZES } from './source.js';
 import { msg } from '../../i18n/index.js';
@@ -41,10 +36,6 @@ const LIFT_STEP = 500;
 // draw nothing until the full-extent image has arrived, and sample the detail
 // image only once it has arrived. The window is west, south, east, north in the
 // full-extent image's texture coordinates.
-// `infrared` is how much of the cloud key applies, 0–1 (infraredAlpha.js has
-// the same curve for the globe's draped imagery). It is applied here, to the
-// image as it was decoded, so a 4096×2048 frame is never read back and
-// rewritten on the page, and a strength change is one uniform, not a new image.
 const MATERIAL_SOURCE = `czm_material czm_getMaterial(czm_materialInput materialInput)
 {
   czm_material material = czm_getDefaultMaterial(materialInput);
@@ -55,8 +46,7 @@ const MATERIAL_SOURCE = `czm_material czm_getMaterial(czm_materialInput material
   float useDetail = inside * step(1.5, float(detailDimensions.x));
   vec4 c = mix(coarse, texture(detail, clamp(dst, 0.0, 1.0)), useDetail);
   material.diffuse = czm_gammaCorrect(c.rgb);
-  float key = smoothstep(${INFRARED_ALPHA_T0.toFixed(4)}, ${INFRARED_ALPHA_T1.toFixed(4)}, pow(max(c.r, max(c.g, c.b)), 2.2));
-  material.alpha = c.a * mix(1.0, key, infrared) * alpha * step(1.5, float(imageDimensions.x));
+  material.alpha = c.a * alpha * step(1.5, float(imageDimensions.x));
   return material;
 }
 `;
@@ -73,7 +63,6 @@ function registerMaterial(cesium) {
         image: cesium.Material.DefaultImageId,
         detail: cesium.Material.DefaultImageId,
         alpha: 1,
-        infrared: 0,
         window: { type: 'vec4', x: 0, y: 0, z: -1, w: -1 },
       },
       // Diffuse and alpha share these samples, so one source, not components.
@@ -256,12 +245,6 @@ export function createShellSurface({
       material.uniforms.alpha = value;
       scene.requestRender();
     },
-    /** How much of the infrared cloud key applies, 0–1. */
-    setInfrared(value) {
-      if (destroyed || material.uniforms.infrared === value) return;
-      material.uniforms.infrared = value;
-      scene.requestRender();
-    },
     /** Draw `next` inside `rect` (west, south, east, north in the full-extent
      * image's texture coordinates, 0–1); null clears it. In the same window only
      * the image changes, and Cesium keeps drawing the previous texture until
@@ -455,11 +438,10 @@ export function createWeatherShell({
   const visible = () => !hidden && !suspended();
   const boundsKey = ({ west, south, east, north }) =>
     `${west},${south},${east},${north}`;
-  // One image per time and window: the infrared mode is a uniform, not pixels.
-  const cacheKey = (time, box = null) =>
-    box ? `${time}|${boundsKey(box)}` : time;
+  const cacheKey = (time, mode, box = null) =>
+    `${time}|${infrared ? mode : 'none'}${box ? `|${boundsKey(box)}` : ''}`;
   const wantedDetail = () =>
-    current && view ? cacheKey(current.time, view) : null;
+    current && view ? cacheKey(current.time, current.infrared, view) : null;
 
   function evict(keep = []) {
     const kept = new Set([...keep, current?.key, detail?.key]);
@@ -472,11 +454,12 @@ export function createWeatherShell({
   }
   async function acquire(
     time,
+    mode,
     signal,
     { box = null, keep = [], onFetched } = {},
   ) {
     signal.throwIfAborted();
-    const key = cacheKey(time, box);
+    const key = cacheKey(time, mode, box);
     const entry = images.get(key);
     if (entry) {
       images.delete(key);
@@ -485,8 +468,7 @@ export function createWeatherShell({
     }
     const result = await acquireWeatherImage(product, time, {
       signal,
-      // The surface's shader applies the infrared transfer.
-      transfer: false,
+      mode,
       size: box ? detailSize : size,
       bbox: box,
       maxBytes: MAX_IMAGE_BYTES,
@@ -582,7 +564,9 @@ export function createWeatherShell({
     const job = { key, box: view, controller: new AbortController() };
     detailJob = job;
     job.timeout = setTimeout(() => job.controller.abort(), timeoutMs);
-    void acquire(current.time, job.controller.signal, { box: view })
+    void acquire(current.time, current.infrared, job.controller.signal, {
+      box: view,
+    })
       .then(({ texture }) => installDetail(job, texture))
       .catch(() => failDetail(job));
   }
@@ -677,7 +661,6 @@ export function createWeatherShell({
       loadMs: now() - frame.startedAt,
     };
     surface.setAlpha(alpha);
-    surface.setInfrared(infrared ? infraredAmount(frame.infrared) : 0);
     applyVisibility();
     lastError = null;
     evict();
@@ -732,7 +715,7 @@ export function createWeatherShell({
       return changed;
     },
     cancelPrefetch,
-    async prefetch(snapshot, time) {
+    async prefetch(snapshot, time, { infrared: mode = 'filtered' } = {}) {
       let job;
       try {
         if (
@@ -746,8 +729,8 @@ export function createWeatherShell({
         // Warm the next frame's detail window too while the window stays put.
         const box =
           view && viewBounds === boundsKey(snapshot.bounds) ? view : null;
-        const coarse = cacheKey(time);
-        const key = box ? cacheKey(time, box) : coarse;
+        const coarse = cacheKey(time, mode);
+        const key = box ? cacheKey(time, mode, box) : coarse;
         if (prefetchJob?.key === key || prefetchedKey === key) return false;
         cancelPrefetch();
         job = { key, controller: new AbortController() };
@@ -756,8 +739,8 @@ export function createWeatherShell({
         job.timeout = setTimeout(() => job.controller.abort(), timeoutMs);
         // Both images at once: one after the other would outlast playback's step.
         await Promise.all([
-          acquire(time, signal, { keep: box ? [key] : [] }),
-          box ? acquire(time, signal, { box, keep: [coarse] }) : null,
+          acquire(time, mode, signal, { keep: box ? [key] : [] }),
+          box ? acquire(time, mode, signal, { box, keep: [coarse] }) : null,
         ]);
         signal.throwIfAborted();
         if (prefetchJob === job) prefetchedKey = key;
@@ -799,7 +782,7 @@ export function createWeatherShell({
         infrared: mode,
         bounds,
         product: snapshot.product,
-        key: cacheKey(time),
+        key: cacheKey(time, mode),
         mosaic: { fetched: false, decodeMs: null, cached: false },
         controller: new AbortController(),
         startedAt: now(),
@@ -814,7 +797,7 @@ export function createWeatherShell({
       });
       watch(frame, signal);
       frame.timeout = setTimeout(() => fail(frame), timeoutMs);
-      void acquire(time, frame.controller.signal, {
+      void acquire(time, mode, frame.controller.signal, {
         onFetched: () => {
           frame.mosaic.fetched = true;
         },

src/layers/weather/shellRendering.test.mjs

@@ -11,7 +11,6 @@ import {
   WEATHER_SHELL_HEIGHTS,
 } from './shellRendering.js';
 import { NO_IMAGERY_HOST } from './imageryHost.js';
-import { INFRARED_ALPHA_T0, INFRARED_ALPHA_T1 } from './infraredAlpha.js';
 import {
   createShellCesium,
   createShellScene,
@@ -148,13 +147,12 @@ test('surface builds a flat raised rectangle drawn in primitive order without de
     image: Cesium.Material.DefaultImageId,
     detail: Cesium.Material.DefaultImageId,
     alpha: 1,
-    infrared: 0,
     window: { type: 'vec4', x: 0, y: 0, z: -1, w: -1 },
   });
   const { source } = template.fabric;
   assert.match(
     source,
-    /material\.alpha = c\.a \* mix\(1\.0, key, infrared\) \* alpha \* step\(1\.5, float\(imageDimensions\.x\)\);/,
+    /material\.alpha = c\.a \* alpha \* step\(1\.5, float\(imageDimensions\.x\)\);/,
     'nothing draws before the full-extent image',
   );
   assert.match(
@@ -375,7 +373,6 @@ test('real Cesium builds the two-texture material, the opaque-pass appearance an
     /uniform sampler2D image_\d+;/,
     /uniform sampler2D detail_\d+;/,
     /uniform float alpha_\d+;/,
-    /uniform float infrared_\d+;/,
     /uniform vec4 window_\d+;/,
     /uniform ivec3 imageDimensions_\d+;/,
     /uniform ivec3 detailDimensions_\d+;/,
@@ -387,16 +384,9 @@ test('real Cesium builds the two-texture material, the opaque-pass appearance an
   assert.match(shader, /step\(1\.5, float\(detailDimensions_\d+\.x\)\)/);
   assert.match(
     shader,
-    /material\.alpha = c\.a \* mix\(1\.0, key, infrared_\d+\) \* alpha_\d+ \* step\(1\.5, float\(imageDimensions_\d+\.x\)\);/,
+    /material\.alpha = c\.a \* alpha_\d+ \* step\(1\.5, float\(imageDimensions_\d+\.x\)\);/,
     'the uniform is renamed, the material field is not',
   );
-  // The cloud key the globe's draped imagery gets from infraredAlpha.js:
-  // brightest channel, 2.2 power, the shared thresholds.
-  assert.ok(
-    shader.includes(
-      `float key = smoothstep(${INFRARED_ALPHA_T0.toFixed(4)}, ${INFRARED_ALPHA_T1.toFixed(4)}, pow(max(c.r, max(c.g, c.b)), 2.2));`,
-    ),
-  );
   assert.match(shader, /float useDetail = inside \* step/, 'locals keep names');
   const detail = { width: 4096, height: 2048 };
   surface.setDetail(detail, { west: 0.1, south: 0.2, east: 0.3, north: 0.4 });
@@ -753,12 +743,12 @@ test('prefetch warms a decoded frame without staging and cancels cleanly', async
   h.shell.clear();
 });
 
-test('infrared frames reach the shader as decoded, with the cloud key as a uniform; radar and lightning get none', async () => {
-  for (const [product, amount] of [
-    ['clouds-regional', 1],
-    ['clouds', 1],
-    ['radar', 0],
-    ['lightning', 0],
+test('infrared frames get the display transfer; radar and lightning keep their pixels', async () => {
+  for (const [product, transfer] of [
+    ['clouds-regional', true],
+    ['clouds', true],
+    ['radar', false],
+    ['lightning', false],
   ]) {
     const h = harness({ product });
     const pending = h.shell.setFrame(snapshot(product), times[0]);
@@ -766,10 +756,11 @@ test('infrared frames reach the shader as decoded, with the cloud key as a unifo
     const image = h.material().uniforms.image;
     assert.equal(image.source, h.decoded[0], 'drawn into a canvas');
     assert.equal(h.decoded[0].closed, true);
-    assert.equal(image.pixels, undefined, `${product}: pixels never rewritten`);
+    assert.equal(image.pixels !== undefined, transfer, product);
+    if (transfer)
+      assert.deepEqual([...image.pixels], [194, 0, 0, 98], 'clouds only');
     h.render();
     assert.equal(await pending, true);
-    assert.equal(h.material().uniforms.infrared, amount, product);
     assert.equal(
       h.shell.getDiagnostics().height,
       WEATHER_SHELL_HEIGHTS[product],
@@ -778,28 +769,20 @@ test('infrared frames reach the shader as decoded, with the cloud key as a unifo
   }
 });
 
-test('an infrared mode change is a uniform on the same image: no fetch, no new canvas', async () => {
+test('an infrared mode change restages the same time with its own cached canvas', async () => {
   const h = harness({ product: 'clouds' });
   assert.equal(await show(h, times[0]), true);
-  const image = h.material().uniforms.image;
-  assert.equal(h.material().uniforms.infrared, 1);
+  const filtered = h.material().uniforms.image;
   assert.equal(await show(h, times[0]), true, 'same frame is a no-op');
   assert.equal(h.fetches.length, 1);
-  const renders = h.scene.renders;
   assert.equal(await show(h, times[0], { infrared: 'full' }), true);
-  assert.equal(h.material().uniforms.image, image);
-  assert.equal(h.material().uniforms.infrared, 0);
+  const full = h.material().uniforms.image;
+  assert.notEqual(full, filtered);
+  assert.deepEqual([...full.pixels], [194, 0, 0, 200]);
   assert.equal(h.shell.getDiagnostics().infrared, 'full');
-  assert.ok(h.scene.renders > renders, 'the new strength is drawn');
-  assert.equal(await show(h, times[0], { infrared: 40 }), true);
-  assert.equal(h.material().uniforms.infrared, 0.4);
-  assert.equal(h.shell.getDiagnostics().infrared, 40);
   assert.equal(await show(h, times[0], { infrared: 'filtered' }), true);
-  assert.equal(h.material().uniforms.image, image);
-  assert.equal(h.material().uniforms.infrared, 1);
-  assert.equal(h.fetches.length, 1);
-  assert.equal(h.decoded.length, 1);
-  assert.equal(h.shell.getDiagnostics().cache.mosaics, 1);
+  assert.equal(h.material().uniforms.image, filtered, 'cache hit');
+  assert.equal(h.fetches.length, 2);
   h.shell.clear();
 });