算法来源与许可

The /lab/ page is an experiment, not ten scientifically validated cloud presets.

Takram

Repository: three-geospatial.
@takram/three-clouds 0.7.6, @takram/three-atmosphere 0.19.1, @takram/three-geospatial 0.9.1.
MIT license: download LICENSE.txt.
Cloud assets: revision 45a1c6c1bb9fd38b3680fd120795ff4c32df68ff.
Atmosphere lookup tables: revision eac103980f20c0956f2d3215833e73514be08462.
STBN data: revision 9627216cc50057994c98a2118f3c4a23765d43b9.
STBN texture data originates from NVIDIA's Spatiotemporal Blue Noise SDK. Its upstream license is included separately; do not assume this asset is covered by Takram's MIT license.
Volume rendering follows the official vanilla Three.js example. The application integrates wind and evolution offsets separately, with explicit pause, time scaling and stepping.

Copyright © 2021–2025 Benjamin Stott (SixthSurge).
Repository: Photon.
Source revision: 15458c0937f8647c37eb6a501bef5eb3bf3da31b.
Source files: shaders/include/sky/clouds/cirrus.glsl, common.glsl, shaders/include/utility/random.glsl, shaders/image/noise.png.
Full custom license: download LICENSE.txt. Photon code/assets are not MIT licensed. Redistribution is subject to the upstream license, including its monetization restrictions.
src/lab/photon.frag.glsl retains the earlier cirrus and cirrocumulus density functions and curl noise, retaining the original noise texture. The lab now uses it only for cirrocumulus; cirrus uses the separate model below. Independent evolution time, browser coordinates, a thin layer and simplified lighting are adaptations. Solar elevation and azimuth drive all lab modes; thin-cloud sunlight colour is sampled from Takram's atmospheric transmittance LUT. This does not reproduce Photon's complete lighting pipeline or imply identical visuals.
src/shaders/cirrocumulus.glsl also adapts Photon density, curl noise and multi-scale erosion for the home atlas, using the same original noise texture. Separate coverage, local ripple organisation, ground-view projection, a smooth height profile, four-sample optical-depth integration and mipmap filtering are project adaptations. Home lighting remains simplified; it is not the complete Photon renderer.
Gradient-noise derivative credited upstream to Inigo Quilez.
Hash credited upstream to Dave Hoskins.

Visual targets: WMO International Cloud Atlas, Cirrus fibratus and uncinus, and Met Office, Cloud types for observers, printed page 33. No photographs are bundled with the application.
Hogan, R. J. and Kew, S. F. (2005), A 3D stochastic cloud model for investigating the radiative properties of inhomogeneous cirrus clouds, Q. J. R. Meteorol. Soc., 131, 2585–2608.
src/lab/cirrus.frag.glsl is an original morphology-driven approximation inspired by fallstreak displacement, wind shear and the spread of ice fall speeds. Sparse generating regions, height-dependent analytical trajectories and anisotropic texture detail define the thin volume. It does not implement the paper's Fourier model, ice microphysics or a numerical weather solver.
No source code or datasets from the GPL-2.0 Cloudgen implementation were incorporated. The model reuses the existing Takram shape texture and atmospheric lookup tables; it adds no external runtime assets.
src/lab/CirrusEffect.ts integrates the thin volume at reduced resolution and filters four sampling phases with a short history. Edits and seeks reset the history. Solar elevation and azimuth use the lab's shared controls.

All reference assets are served locally; the home atlas and experiment make no runtime requests to GitHub or other external asset hosts.