mirror of
https://github.com/bilawalsidhu/gods-eye-view.git
synced 2026-11-06 11:24:00 +00:00
feat(sky): replace the blocky default sky box with catalogue stars
Cesium's default Tycho-2 sky box is six 1024² JPEGs stretched 3–6× around the whole-globe view, so space read as an over-compressed JPEG (HAL-627). The scene now draws its own sky in the Scene#skyBox slot: the 9,096 stars of the Yale Bright Star Catalogue as point sprites sized in CSS pixels (magnitude → width and opacity, B−V → colour), over a soft, star-free Milky Way cube map built from ESO/S. Brunier's panorama (CC BY 4.0). Both layers share one ICRF→Earth-fixed rotation at the scene clock, with the TEME rotation filling in until Cesium's IAU 2006 tables load. Assets total 482 KB, built by scripts/build-bright-stars.mjs and scripts/build-milky-way.mjs. Frame time and the idle render governor are unchanged. Co-Authored-By: Claude Opus 5.5 <[email protected]>
This commit is contained in:
German KhokhlovandClaude Opus 5.5 committed
1 parent
93ea088f45
commit
6549344946
20 files changed
+10644
-2
No files matched your search
@@ -0,0 +1,372 @@
|
||||
#!/usr/bin/env node
|
||||
/**
|
||||
* Build the soft Milky Way cube map in src/data/local_data/sky/ from the ESO
|
||||
* all-sky Milky Way panorama.
|
||||
*
|
||||
* Source page: https://www.eso.org/public/images/eso0932a/
|
||||
* Fetched: https://cdn.eso.org/images/original/eso0932a.tif
|
||||
* (6000×3000 8-bit sRGB TIFF, 27.7 MB; sha256 in README.md)
|
||||
* Credit: ESO/S. Brunier
|
||||
* License: CC BY 4.0 (https://www.eso.org/public/outreach/copyright/).
|
||||
* Modified: stars removed, blurred, reprojected to ICRF cube
|
||||
* faces and tone-mapped, as below.
|
||||
* Frame: plate carrée in galactic coordinates, centred on the Galactic
|
||||
* Centre, galactic longitude increasing to the left.
|
||||
*
|
||||
* Transform (deterministic):
|
||||
* 1. Resample to WORK_WIDTH×WORK_WIDTH/2 and convert sRGB to linear light.
|
||||
* 2. Paint out the planets the 2008–2010 exposures caught (PLANETS): they
|
||||
* sit where today's sky has nothing and are far brighter than any star.
|
||||
* 3. Remove stars with a morphological opening (minimum, then maximum, over
|
||||
* a (2·OPEN_RADIUS+1)² window): anything smaller than the window — every
|
||||
* star — drops to the surrounding sky; the renderer draws catalogue stars
|
||||
* itself, sharp and in the right place.
|
||||
* 4. Blur with a three-pass box approximation of a Gaussian, σ = BLUR_DEG on
|
||||
* the sky: rows wrap in longitude and widen by 1/cos(latitude) so the
|
||||
* blur stays round towards the poles.
|
||||
* 5. Resample into six FACE_SIZE² cube faces in the standard WebGL face
|
||||
* orientation (the renderer uploads them without flipY), with the ICRF
|
||||
* axes as the cube axes — +X to the March equinox, +Z to the north
|
||||
* celestial pole — rotating each direction into galactic coordinates
|
||||
* with the IAU J2000 matrix.
|
||||
* 6. Map the darkest 25 % of the sky to black and the brightest 0.01 % to
|
||||
* white, encode with gamma 1/2.2 and ±0.5 LSB dither against banding;
|
||||
* WebP.
|
||||
*
|
||||
* Usage:
|
||||
* node scripts/build-milky-way.mjs <eso0932a.tif>
|
||||
* Needs the sharp dev dependency.
|
||||
*/
|
||||
|
||||
import path from 'node:path';
|
||||
import { fileURLToPath } from 'node:url';
|
||||
|
||||
export const FACE_SIZE = 1024;
|
||||
export const BLUR_DEG = 0.4;
|
||||
const WORK_WIDTH = 4096;
|
||||
const OPEN_RADIUS = 3;
|
||||
const WEBP_QUALITY = 96;
|
||||
// The darkest quarter of the sky is the black level: away from the galactic
|
||||
// plane the panorama carries a mottled glow of unresolved stars that would
|
||||
// read as grey fog around the globe.
|
||||
const BLACK_PERCENTILE = 0.25;
|
||||
const WHITE_PERCENTILE = 0.9999;
|
||||
const OUT_DIR = path.join(
|
||||
path.dirname(fileURLToPath(import.meta.url)),
|
||||
'..',
|
||||
'src',
|
||||
'data',
|
||||
'local_data',
|
||||
'sky',
|
||||
);
|
||||
|
||||
/**
|
||||
* Bright planets in the panorama, galactic longitude/latitude in degrees and
|
||||
* the radius painted over with the surrounding sky. By position both are
|
||||
* Jupiter, in Sagittarius (2008) and Aquarius (2010); no catalogue star lies
|
||||
* under either.
|
||||
*/
|
||||
export const PLANETS = Object.freeze([
|
||||
{ l: 13.4, b: -16.6, radiusDeg: 2.5 },
|
||||
{ l: 69.0, b: -58.4, radiusDeg: 2.5 },
|
||||
]);
|
||||
|
||||
/** Cube faces in WebGL upload order. */
|
||||
export const CUBE_FACES = Object.freeze([
|
||||
'positiveX',
|
||||
'negativeX',
|
||||
'positiveY',
|
||||
'negativeY',
|
||||
'positiveZ',
|
||||
'negativeZ',
|
||||
]);
|
||||
export const FACE_FILE_SUFFIX = Object.freeze({
|
||||
positiveX: 'px',
|
||||
negativeX: 'nx',
|
||||
positiveY: 'py',
|
||||
negativeY: 'ny',
|
||||
positiveZ: 'pz',
|
||||
negativeZ: 'nz',
|
||||
});
|
||||
|
||||
/**
|
||||
* ICRF (J2000 equatorial) → galactic rotation, rows = galactic axes
|
||||
* (Hipparcos catalogue, ESA SP-1200 vol. 1 §1.5.3).
|
||||
*/
|
||||
export const ICRF_TO_GALACTIC = Object.freeze([
|
||||
[-0.0548755604162154, -0.873437090234885, -0.4838350155487132],
|
||||
[0.4941094278755837, -0.4448296299600112, 0.7469822444972189],
|
||||
[-0.867666149019004, -0.1980763734312015, 0.4559837761750669],
|
||||
]);
|
||||
|
||||
/**
|
||||
* Direction (not normalized) that the WebGL cube-map lookup sends to texel
|
||||
* coordinate (s, t) ∈ [0, 1]² of `face`, t = 0 being the first image row.
|
||||
* Inverse of the OpenGL ES 3.0 §3.8.10 major-axis table.
|
||||
*/
|
||||
export function cubeFaceDirection(face, s, t) {
|
||||
const sc = 2 * s - 1;
|
||||
const tc = 2 * t - 1;
|
||||
switch (face) {
|
||||
case 'positiveX':
|
||||
return [1, -tc, -sc];
|
||||
case 'negativeX':
|
||||
return [-1, -tc, sc];
|
||||
case 'positiveY':
|
||||
return [sc, 1, tc];
|
||||
case 'negativeY':
|
||||
return [sc, -1, -tc];
|
||||
case 'positiveZ':
|
||||
return [sc, -tc, 1];
|
||||
case 'negativeZ':
|
||||
return [-sc, -tc, -1];
|
||||
default:
|
||||
throw new RangeError(`Unknown cube face ${face}`);
|
||||
}
|
||||
}
|
||||
|
||||
/** Rotate an ICRF direction into galactic coordinates. */
|
||||
export function icrfToGalactic([x, y, z]) {
|
||||
return ICRF_TO_GALACTIC.map((row) => row[0] * x + row[1] * y + row[2] * z);
|
||||
}
|
||||
|
||||
/**
|
||||
* Map a direction to (u, v) ∈ [0, 1)² of a plate carrée centred on
|
||||
* longitude 0 with longitude increasing to the left and v = 0 at +90°.
|
||||
*/
|
||||
export function directionToPlateCarree(x, y, z) {
|
||||
const longitude = Math.atan2(y, x);
|
||||
const latitude = Math.atan2(z, Math.hypot(x, y));
|
||||
let u = 0.5 - longitude / (2 * Math.PI);
|
||||
u -= Math.floor(u);
|
||||
return [u, 0.5 - latitude / Math.PI];
|
||||
}
|
||||
|
||||
/** Box widths whose three passes approximate a Gaussian of `sigma` (Kovesi). */
|
||||
function boxRadii(sigma) {
|
||||
const ideal = Math.sqrt((12 * sigma * sigma) / 3 + 1);
|
||||
let lower = Math.floor(ideal);
|
||||
if (lower % 2 === 0) lower -= 1;
|
||||
const upper = lower + 2;
|
||||
const m = Math.round(
|
||||
(12 * sigma * sigma - 3 * lower * lower - 12 * lower - 9) /
|
||||
(-4 * lower - 4),
|
||||
);
|
||||
return [0, 1, 2].map((i) => ((i < m ? lower : upper) - 1) / 2);
|
||||
}
|
||||
|
||||
/** Index along a line, wrapped or clamped at the ends. */
|
||||
function lineIndex(i, length, wrap) {
|
||||
if (wrap) return ((i % length) + length) % length;
|
||||
return i < 0 ? 0 : i >= length ? length - 1 : i;
|
||||
}
|
||||
|
||||
/** Running-sum box blur of one strided line. */
|
||||
function boxLine(src, dst, offset, stride, length, radius, wrap) {
|
||||
if (radius < 1) {
|
||||
for (let i = 0; i < length; i++)
|
||||
dst[offset + i * stride] = src[offset + i * stride];
|
||||
return;
|
||||
}
|
||||
const r = wrap ? Math.min(radius, Math.floor((length - 1) / 2)) : radius;
|
||||
const at = (i) => src[offset + lineIndex(i, length, wrap) * stride];
|
||||
let sum = 0;
|
||||
for (let i = -r; i <= r; i++) sum += at(i);
|
||||
const scale = 1 / (2 * r + 1);
|
||||
for (let i = 0; i < length; i++) {
|
||||
dst[offset + i * stride] = sum * scale;
|
||||
sum += at(i + r + 1) - at(i - r);
|
||||
}
|
||||
}
|
||||
|
||||
/** Minimum or maximum over a (2r+1) window of one strided line. */
|
||||
function extremumLine(src, dst, offset, stride, length, radius, wrap, pick) {
|
||||
for (let i = 0; i < length; i++) {
|
||||
let value = src[offset + lineIndex(i - radius, length, wrap) * stride];
|
||||
for (let k = -radius + 1; k <= radius; k++)
|
||||
value = pick(
|
||||
value,
|
||||
src[offset + lineIndex(i + k, length, wrap) * stride],
|
||||
);
|
||||
dst[offset + i * stride] = value;
|
||||
}
|
||||
}
|
||||
|
||||
/** Separable minimum or maximum filter over a plate-carrée plane, in place. */
|
||||
function extremumPlane(plane, width, height, radius, pick) {
|
||||
const scratch = new Float32Array(plane.length);
|
||||
for (let y = 0; y < height; y++)
|
||||
extremumLine(plane, scratch, y * width, 1, width, radius, true, pick);
|
||||
for (let x = 0; x < width; x++)
|
||||
extremumLine(scratch, plane, x, width, height, radius, false, pick);
|
||||
}
|
||||
|
||||
/** Blur one plate-carrée channel in place, round on the sphere. */
|
||||
function blurPlane(plane, width, height, sigmaPx) {
|
||||
const scratch = new Float32Array(plane.length);
|
||||
for (let y = 0; y < height; y++) {
|
||||
const latitude = (0.5 - (y + 0.5) / height) * Math.PI;
|
||||
const sigmaX = Math.min(
|
||||
width / 4,
|
||||
sigmaPx / Math.max(Math.cos(latitude), 1e-3),
|
||||
);
|
||||
for (const radius of boxRadii(sigmaX)) {
|
||||
boxLine(plane, scratch, y * width, 1, width, Math.round(radius), true);
|
||||
plane.set(scratch.subarray(y * width, (y + 1) * width), y * width);
|
||||
}
|
||||
}
|
||||
for (const radius of boxRadii(sigmaPx)) {
|
||||
for (let x = 0; x < width; x++)
|
||||
boxLine(plane, scratch, x, width, height, Math.round(radius), false);
|
||||
plane.set(scratch);
|
||||
}
|
||||
}
|
||||
|
||||
/** Unit vector for galactic longitude and latitude in degrees. */
|
||||
function galacticVector(l, b) {
|
||||
const lr = (l * Math.PI) / 180;
|
||||
const br = (b * Math.PI) / 180;
|
||||
return [
|
||||
Math.cos(br) * Math.cos(lr),
|
||||
Math.cos(br) * Math.sin(lr),
|
||||
Math.sin(br),
|
||||
];
|
||||
}
|
||||
|
||||
/**
|
||||
* Replace a disc of the sky with the mean of the ring just outside it, per
|
||||
* channel. The blur that follows hides the seam.
|
||||
*/
|
||||
function paintOut(planes, width, height, { l, b, radiusDeg }) {
|
||||
const centre = galacticVector(l, b);
|
||||
const inner = Math.cos((radiusDeg * Math.PI) / 180);
|
||||
const outer = Math.cos(((radiusDeg + 0.5) * Math.PI) / 180);
|
||||
const disc = [];
|
||||
const ring = [];
|
||||
const span = Math.ceil(((radiusDeg + 0.5) / 180) * height);
|
||||
const row = Math.round((0.5 - b / 180) * height);
|
||||
for (let y = Math.max(0, row - span); y < Math.min(height, row + span); y++) {
|
||||
const latitude = 90 - ((y + 0.5) * 180) / height;
|
||||
for (let x = 0; x < width; x++) {
|
||||
const longitude = (0.5 - (x + 0.5) / width) * 360;
|
||||
const p = galacticVector(longitude, latitude);
|
||||
const cos = p[0] * centre[0] + p[1] * centre[1] + p[2] * centre[2];
|
||||
if (cos >= inner) disc.push(y * width + x);
|
||||
else if (cos >= outer) ring.push(y * width + x);
|
||||
}
|
||||
}
|
||||
for (const plane of planes) {
|
||||
let sum = 0;
|
||||
for (const index of ring) sum += plane[index];
|
||||
const mean = sum / ring.length;
|
||||
for (const index of disc) plane[index] = mean;
|
||||
}
|
||||
}
|
||||
|
||||
/** Bilinear sample with longitude wrap and latitude clamp. */
|
||||
function samplePlane(plane, width, height, u, v) {
|
||||
const fx = u * width - 0.5;
|
||||
const fy = Math.min(Math.max(v * height - 0.5, 0), height - 1);
|
||||
const x0 = Math.floor(fx);
|
||||
const y0 = Math.floor(fy);
|
||||
const ax = fx - x0;
|
||||
const ay = fy - y0;
|
||||
const xa = ((x0 % width) + width) % width;
|
||||
const xb = (xa + 1) % width;
|
||||
const yb = Math.min(y0 + 1, height - 1);
|
||||
const top = plane[y0 * width + xa] * (1 - ax) + plane[y0 * width + xb] * ax;
|
||||
const bottom =
|
||||
plane[yb * width + xa] * (1 - ax) + plane[yb * width + xb] * ax;
|
||||
return top * (1 - ay) + bottom * ay;
|
||||
}
|
||||
|
||||
/** Deterministic hash noise in [-0.5, 0.5) for dithering. */
|
||||
function dither(index, channel) {
|
||||
let h = (index * 374761393 + channel * 668265263) | 0;
|
||||
h = Math.imul(h ^ (h >>> 13), 1274126177);
|
||||
h ^= h >>> 16;
|
||||
return (h >>> 0) / 4294967296 - 0.5;
|
||||
}
|
||||
|
||||
/** Value at `fraction` of the sorted luminance. */
|
||||
function luminancePercentile(planes, fraction) {
|
||||
const [r, g, b] = planes;
|
||||
const lum = new Float32Array(r.length);
|
||||
for (let i = 0; i < lum.length; i++) lum[i] = (r[i] + g[i] + b[i]) / 3;
|
||||
lum.sort();
|
||||
return lum[Math.min(lum.length - 1, Math.floor(fraction * lum.length))];
|
||||
}
|
||||
|
||||
const srgbToLinear = (value) =>
|
||||
value <= 0.04045 ? value / 12.92 : ((value + 0.055) / 1.055) ** 2.4;
|
||||
|
||||
async function decodePanorama(sharp, file) {
|
||||
const width = WORK_WIDTH;
|
||||
const height = WORK_WIDTH / 2;
|
||||
const raw = await sharp(file)
|
||||
.resize(width, height, { fit: 'fill', kernel: 'lanczos3' })
|
||||
.removeAlpha()
|
||||
.raw()
|
||||
.toBuffer();
|
||||
const lut = Float32Array.from({ length: 256 }, (_, i) =>
|
||||
srgbToLinear(i / 255),
|
||||
);
|
||||
const planes = [0, 1, 2].map(() => new Float32Array(width * height));
|
||||
for (let i = 0; i < width * height; i++)
|
||||
for (let c = 0; c < 3; c++) planes[c][i] = lut[raw[i * 3 + c]];
|
||||
return { width, height, planes };
|
||||
}
|
||||
|
||||
async function main() {
|
||||
const [file] = process.argv.slice(2);
|
||||
if (!file) throw new Error('usage: build-milky-way.mjs <eso0932a.tif>');
|
||||
const { default: sharp } = await import('sharp');
|
||||
const { width, height, planes } = await decodePanorama(sharp, file);
|
||||
const sigmaPx = (BLUR_DEG / 180) * height;
|
||||
for (const planet of PLANETS) paintOut(planes, width, height, planet);
|
||||
for (const plane of planes) {
|
||||
extremumPlane(plane, width, height, OPEN_RADIUS, Math.min);
|
||||
extremumPlane(plane, width, height, OPEN_RADIUS, Math.max);
|
||||
blurPlane(plane, width, height, sigmaPx);
|
||||
}
|
||||
const black = luminancePercentile(planes, BLACK_PERCENTILE);
|
||||
const white = luminancePercentile(planes, WHITE_PERCENTILE);
|
||||
let total = 0;
|
||||
for (const face of CUBE_FACES) {
|
||||
const pixels = Buffer.alloc(FACE_SIZE * FACE_SIZE * 3);
|
||||
for (let j = 0; j < FACE_SIZE; j++) {
|
||||
for (let i = 0; i < FACE_SIZE; i++) {
|
||||
const direction = cubeFaceDirection(
|
||||
face,
|
||||
(i + 0.5) / FACE_SIZE,
|
||||
(j + 0.5) / FACE_SIZE,
|
||||
);
|
||||
const [u, v] = directionToPlateCarree(...icrfToGalactic(direction));
|
||||
const index = j * FACE_SIZE + i;
|
||||
for (let c = 0; c < 3; c++) {
|
||||
const linear = Math.max(
|
||||
(samplePlane(planes[c], width, height, u, v) - black) /
|
||||
(white - black),
|
||||
0,
|
||||
);
|
||||
const encoded = Math.min(linear, 1) ** (1 / 2.2) * 255;
|
||||
pixels[index * 3 + c] = Math.min(
|
||||
255,
|
||||
Math.max(0, Math.round(encoded + dither(index, c))),
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
const out = path.join(OUT_DIR, `milkyway_${FACE_FILE_SUFFIX[face]}.webp`);
|
||||
const info = await sharp(pixels, {
|
||||
raw: { width: FACE_SIZE, height: FACE_SIZE, channels: 3 },
|
||||
})
|
||||
.webp({ quality: WEBP_QUALITY, smartSubsample: true, effort: 6 })
|
||||
.toFile(out);
|
||||
total += info.size;
|
||||
console.log(`${path.relative(process.cwd(), out)}: ${info.size} bytes`);
|
||||
}
|
||||
console.log(`total ${total} bytes`);
|
||||
}
|
||||
|
||||
if (process.argv[1] === fileURLToPath(import.meta.url)) await main();
|
||||
Reference in new issue
Block a user