This is a beta. Everything on this page is in version 1.2.2 and you can use it today. I use it for my own shots, and it runs 210 automated checks headless on Blender 4.2 LTS, 5.1 and 5.2. Beta means I am still polishing it, and the looks of the big set pieces keep improving. Every update is free.

What it does

You pick a cloud type, a seed and a size in metres, then click Generate. Rego Nimbus writes a real OpenVDB file to disk and loads it as a volume with a clean, bright material on it. The cloud in your viewport is the file. There is no second export that bakes it again, so what you see is what goes to Unreal, Houdini or anywhere else.

I wanted clouds that look like clouds: a flat base, a heaped top, lobes that shade each other and a rim that stays crisp against a blue sky. A sphere with a noise texture on it never got me there, so I wrote a generator.

Quality comes first in the panel

Quality is the number of voxels along the longest side of the cloud: Draft 64, Preview 96, Good 160, High 256, Ultra 384. It has Lower and Higher buttons, and next to them the panel shows the voxel size in metres and roughly how long the build will take, before you commit. If a cloud looks blocky, this is the setting.

If a finished render looks grainy instead, that is a different problem, and the Render setting next to Quality handles it. It sets samples, volume step size and bounces for Cycles and EEVEE at three levels.

Nine cloud types

Cumulus, towering cumulus, cumulonimbus with its anvil, stratocumulus, an altocumulus field, stratus and fog banks, cirrus, a stylized puffy cloud for games, and a hurricane.

Under the hood each one starts from a hierarchy of lobes. Smaller lobes grow on the upper surface of bigger ones, so the body stays one connected cloud. Low frequency noise shapes it, five octaves of cellular noise push out the cauliflower bumps, and a finer erosion eats the rim, more at the edge than in the core. You steer it with Coverage, Detail, Billow, Edge softness, Flat base and Wisps, plus Interior variation so the inside has thermals and dry pockets.

A hurricane built from the parts of a hurricane

The Cyclone type does not stack lobes. It is written in cylindrical coordinates, with the structure a real storm has: a clear eye through every level, an eyewall that leans outward as it rises (pilots call this the stadium effect), rainbands on logarithmic spirals that break into convective cells further out, and a cirrus canopy on top, spun the opposite way by the outflow. The eye is a slowly turning polygon rather than a circle, because the small vortices in the eyewall pull it out of round.

Turn on Time or Animate and the storm winds up on a modified Rankine wind profile: the inner air turns faster than the outer air, so the spiral tightens instead of rotating like a plate. You set the peak wind in m/s and the real radius of the storm in kilometres, while the box itself stays a scale model. Northern storms turn anticlockwise and southern ones clockwise, and that is a switch.

Seeds, presets and recipes

Each Generate picks a new seed, so two clicks give two different clouds. The seed is always shown and stored on the object, so any result can be rebuilt exactly. The add-on ships with 24 presets, nine of them based on the WMO cloud genera. You can save your own, export and import them as .json, or copy them through the clipboard. Every exported VDB also carries its recipe in its metadata: open the file in the VDB Inspector months later, press Load Recipe from VDB, and the cloud comes back.

Two looks, and shadows that stay blue

Realistic is soft vapour with light coming through the thin rim. Stylized is denser and more graphic, for games and motion design. In both, the shaded side of the cloud goes sky blue rather than black. A real cloud is lit from below by the whole sky dome and by light bouncing off the ground, and the light rig is built to do the same thing.

Build Light Rig adds a sun, a physical sky at a fraction of the sun's strength with a ground albedo, and a wide sky coloured fill from below so EEVEE gets the effect too. The sky colour follows the sun's height. Sky bounce and Ground albedo are sliders with real values (grass about 0.25, sand 0.4, snow 0.8). There are five more looks: Sunlit silver lining, Studio white, Soft overcast, Storm cell and Golden hour.

The density scale is worked out from the size of the cloud and the look, so a 400 m cumulus and a 4 cm cloud on a table both read correctly the moment they appear.

Your own shapes

Cloud from Mesh voxelises any closed mesh into a real VDB that you can export.

Live Cloud adds a Geometry Nodes modifier that turns an object (mesh, metaball, curve or text) into a volume without baking, so it follows animation, armatures and physics. It is a quick preview route: it stays inside Blender and is not written to a .vdb.

Metaball rig builds a cluster of blobs in the shape of a cumulus. You can move and keyframe them by hand, grow more with Add Children, and Animate Metaballs keyframes drift, rise and a breathing radius on every blob at once.

Morph takes a list of models and bakes a VDB sequence that turns one into the next. It blends the distance fields of the shapes, with an organic bulge halfway through, so the cloud rearranges itself instead of one shape fading into the other. Each step has its own hold time.

Weather and physics

The base sits at the condensation level and stays there. Updraft (in m/s) lifts and swells only the lobes that are already clear of the base, which is how a thermal behaves. Wind shear makes the top drift faster than the base, and Growth, Dissipation and Turbulence do the rest.

With Advanced physics on, the cloud is pushed by the force fields already in your scene (Wind, Vortex, Turbulence, Force, Harmonic) at their real strengths and falloffs, and the domain grows so nothing gets clipped. A mesh with a Collision modifier is carved out of the cloud with a clearance margin, so the cloud flows around a rock instead of through it.

A cloud is static unless Animate is on. Then it writes one light VDB per frame and loads them as a sequence. Time scale is in cloud seconds per real second, because in real time clouds barely move.

Your own 360 skies

Scatter a Sky of Clouds spreads cumulus around the camera, all on the same cloud base, and can add a sea of clouds below and a cirrus layer up high. Render 360 Sky (HDRI) then captures it as an equirectangular map, 2K, 4K or 8K, saved as a 32-bit EXR or a Radiance HDR, and you can light any scene with it.

Export that engines accept

The VDB writer is my own OpenVDB implementation in pure Python: standard Tree_float_5_4_3 topology, a seekable layout with grid offsets, the fog volume class, float32 or half float, and a UniformScaleTranslateMap transform. I checked it against Blender's own OpenVDB reader and against files written by OpenVDB 8.1 and 12.0.

There is one setting per target. Blender, Houdini and Cinema 4D get metres and Z up. Unreal gets centimetres and Z up, and reads the files as Sparse Volume Textures and in Niagara. Unity, Maya and Omniverse get metres and Y up, and you can also set your own unit scale and axis. Export Cloud Pack writes a set of seed variants with a README table, and the VDB Inspector reads the header of any .vdb and tells you in plain words whether an engine will accept it.

Full colour 3D printing

A colour printer cannot print light, so the light goes into the colour. Make Printable Cloud turns the volume into a closed mesh and bakes the sky model into its vertex colours: direct sun with real self shadowing, the blue sky on top and on the sides, and the warm bounce from the ground underneath. The crevices come out darker than the bumps, which is what gives the printed piece its depth.

You set the size in millimetres, smooth and simplify the mesh, push exposure and saturation a little (ink and resin look flatter than a screen), then export GLB or PLY, the formats most full colour printers read. A printability report gives you the triangle count, whether the mesh is watertight and the real size in mm.

What it is not

• It is not a fluid simulator. The weather model is procedural and the force fields move the finished field. Nothing solves Navier-Stokes. If you already have simulation frames, bring them in with Import VDB with Cloud Look and use the looks and the light rig on them.
• Generation runs on the CPU with numpy. A 96 voxel preview takes about a second, 160 voxels a few seconds, 256 around half a minute and 384 a couple of minutes. Sequences build one frame at a time, so start with a short range.
• The VDB files are uncompressed (float or half). They are bigger than Blosc files and they open everywhere. If you need Blosc, save them again from Houdini or from Blender's own bake.
• Cloud from Mesh and Morph need closed meshes. An open shell has no inside.

Transparency

NO AI INSIDE THE PRODUCT. No model, no inference, no telemetry, no network access and no data collection. Every cloud comes from deterministic geometry and noise code that runs offline.

AI does help me while I build: it writes code with me, and it translates my documentation into English, which is not my first language. I have been programming since long before generative tools were mainstream. The parts that matter here are measured: 201 automated checks on Blender 4.2 and 5.2, the VDB writer checked against Blender's reader and against OpenVDB 8.1 and 12.0 files, and the printable mesh checked watertight.

Every image and animation on this page is a render of the add-on's real output, with typography added.

Support

Write to me through the Superhive message box on this page. Updates and support are included for good, with no support period and no renewal fee.