Volumes

Render fog, clouds, smoke, and glowing isosurfaces — soft, lit, three-dimensional looks that fill space instead of sitting on a surface.

A Volume is a chunk of 3D density: think of it as a cloud of "stuff" filling a box in your scene. Light travels through it, scatters inside it, and casts soft shadows on itself. Drop a Volume into a render and you get smoke, mist, nebulae, or a clean shaded surface carved out of a Distance Field.

Rendering a volume

The volume.render node takes a volume-shaped input and renders it. There is no mode dropdown to fuss with — the node looks at what you feed it and does the right thing.

You can wire in:

• A Volume of any kind (smoke from a simulation.smoke sim, a baked field).

• A Distance Field or geometry — points become a density splat, a mesh becomes a smooth shaded surface, Analytic shapes become clean isosurfaces.

• An image, image sequence, or live video — stacked into a 3D box for a volumetric slab look.

Whatever you give it renders through the same engine, so you can swap sources without rebuilding your shading.

Shaping the look

A volume's appearance is controlled by a single material with a handful of channels:

• Colour — a flat colour, a Field, an Expression, or a texture.

• Scattering and absorption — how much light bounces around inside versus gets swallowed. High scattering reads as bright, milky cloud; high absorption reads as dark, heavy smoke.

• Phase — whether light prefers to keep going forward (forward scatter) for that bright silver-lining rim, or spread evenly.

• Transfer function — a Gradient that maps density to colour, so thin wisps and dense cores read differently. Great for fire and energy looks.

• Detail — adds wispy high-frequency erosion at the edges so clouds don't look like a solid blob.

The renderer ships with a rich shading model out of the box — self-shadowing, multi-bounce glow, a forward/back light response, and edge darkening — so volumes look good before you touch a slider. The Detail strength is the one look knob exposed directly; the rest are tuned to look right automatically.

Live video into a volume

You can route a live camera or video stream straight into the Volume node. Frames stack into the 3D box and update every frame, giving you a moving volumetric slab you can light and shade like any other volume — handy for performance visuals.

Performance

Volumes are some of the heaviest things you can render, because the engine has to march a ray through space for every pixel. It works hard to stay fast — skipping empty space, stopping early once a pixel is solid, and reusing work between frames — but a few settings move the dial most:

• Resolution — the size of the voxel box. Higher means crisper detail and more memory. Start modest (128³) and only push higher when you can see the difference.

• Step size / max steps — smaller steps and more of them mean smoother results but slower renders.

• Shadow steps — how carefully the volume shadows itself. Lower for speed, higher for soft, believable depth.

See also

• Distance fields & volumes — what volumes and distance fields actually are

• Fluid & smoke — generating smoke and fire to render

• The render node — putting volumes into a final render

• Lights — lighting that shapes a volume

• Making it faster — keeping heavy renders real-time