Nodes · Blacksmith

Kiln

Blacksmithv2app

Overview

EXPERIMENTAL — still being built. Kiln: a gas simulation that lives in the 3D scene — smoke, fog, steam, dust — solved on a brick grid inside a box you place, emitted from a shape, lit by the scene's lights and drawn through the project camera like any volume. It is a Scene node: view it in the 3D viewport or render it with Render3D; the density and temperature grids ride the same path a VDB file does, so VolumeShade, the depth holdout and the AOVs all apply. Live it simulates on demand up to 240 frames past the last frame it has; heavier shots bake to VDB with ⚒ Bake and play from disk. Colliders (a placed box or sphere, or any scene mesh — imported, animated, deforming) go in its network and hold the gas back; a sim with one runs on the CPU reference until the GPU twin learns solids, and the panel says so. The CPU solver is the reference; the GPU port is what makes it realtime.

How to

How-to

Tab → Kiln, then pick a preset on the panel (Ground fog, Forest fog bank, Campfire…) and press play; the badge shows where it runs and what a step costs.
Tune at a low resolution, then raise it for the final; size_x/y/z fit the domain to the gas.
Double-click the tile to go into its network: add emitters, forces (Wind, Vortex, Spline follow) and colliders there.
Set renderer to final for the render, with spp, bounces and denoise (off / spatial / ai); ⇄ A/B shows Live beside Final first.
Colour: emit_color per emitter with scatter_by = dye mixes any colours like dye; emit_paint with scatter_by = paint goes through the ramp.
⚒ Bake for playback and delivery; wire the scene into a Render3D to comp it. See kiln.

Inputs

Input	What it takes
in	the image this node works on
matte	the alpha that drives this node

Outputs

Output	Type
out	Scene

Parameters

Parameter	Type	Default	What it does
tx	Float	0.0	Translate X — position along the world X axis, metres.
ty	Float	0.0	Translate Y — position along the world Y axis (up), metres.
tz	Float	0.0	Translate Z — position along the world Z axis, metres. The camera looks down −Z.
rx	Float	0.0	Rotate around X, degrees.
ry	Float	0.0	Rotate around Y (turntable), degrees.
rz	Float	0.0	Rotate around Z (roll), degrees.
sx	Float	1.0	Scale along X. 1 = unchanged.
sy	Float	1.0	Scale along Y.
sz	Float	1.0	Scale along Z.
size_x	Float	2.0	The domain box's width in metres. The box stands on the node's origin and is centred on it in x and z.
size_y	Float	3.0	The domain box's height in metres, from the floor up.
size_z	Float	2.0	The domain box's depth in metres.
resolution	Int	64	Voxels across the box's longest side — the realtime-vs-quality dial. On the GPU 64 costs a few milliseconds a frame and 128 stays under 30 ms; without a GPU the CPU solver takes ~300 ms a frame at 64. Every axis rounds to whole 8³ bricks.
substeps	Int	1	Solver steps per frame. 1 is right for gentle fog; fast jets and strong turbulence want 2–3 to keep the motion smooth.
cfl	Float	0.0	Substeps by CFL: 0 keeps `substeps` fixed; 1–2 splits each frame until no cell's gas crosses more than that many cells per substep (from `substeps` up to 8). Fast fire stops smearing; slow fog costs nothing extra.
max_substeps	Int	8	The ceiling on CFL substeps (see `cfl`). A budget, not a stability guarantee: raise it for fine voxels and fast gas and watch the step cost climb with it. The KILN badge says when the solve is asking for more than this, and a solve stepping past its ask can hold for a while and come apart later.
velocity_advection	Choice	linear	How the velocity is carried each substep. `linear` is a blur applied once per substep, so a shot is filtered a little more every frame (the lava-lamp look of a gas solver); `cubic` is 64 taps against 8, about half again on the step, and keeps 19% more at the grid's own Nyquist. EmberGen's ground fire runs cubic on both. `linearcubic`
voxel_advection	Choice	linear	How the smoke, heat, fuel, flames and age are carried each substep. `linear` blurs a little every frame; `cubic` keeps the edges and costs about half again on the step. The fog presets run cubic. `linearcubic`
shutter	Float	0.0	Shutter time as a fraction of a frame: 0.5 = 180°. How long the blur smears.
shutter_samples	Int	9	How many sub-frame samples the bake's velocity-warped motion blur takes across the shutter. 9 is smooth for a 180° shutter; fewer bands, more costs linearly.
bake_slices	Int	1	KQ-4's film tier: how many sub-frame slices a bake writes per frame. The solver steps each frame in that many equal parts and writes every part (slice 0 is the frame's file, the rest sit beside it as .s1, .s2 …); the render draws each slice and averages them — a box shutter over the frame, true for curved motion and for gas that appears mid-frame, which the velocity warp (`shutter`) is not. Costs that many renders a frame and that much disk. 1 = off. Slices take precedence over the warp.
density_threshold	Float	0.0	Volume processing, on the way OUT: density below this is dropped before the grid is published or baked. In the field's own units (the badge's percentiles read off it). The gas itself is never touched, so a threshold is a look decision, not a different sim; changing it re-packs the running sim from a checkpoint and stales a bake on disk.
density_gain	Float	1.0	Volume processing: the published density multiplied, after the threshold. 1 = as solved.
density_gamma	Float	1.0	Volume processing: a power on the published density after the threshold and gain. 1 = as solved; above 1 thins the haze and keeps the core.
temperature_threshold	Float	0.0	Volume processing: temperature below this publishes as 0. In the temperature's own units.
temperature_gain	Float	1.0	Volume processing: the published temperature multiplied. 1 = as solved.
flames_threshold	Float	0.0	Volume processing: flames below this publish as 0 — crisp flame borders without changing what burns.
flames_gain	Float	1.0	Volume processing: the published flames multiplied. 1 = as solved.
loop	Int	0	FS-7: bake a seamless loop of this many frames. The bake runs two copies of the sim N frames apart and crossfades them (Houdini's Make Loop), so the frame after the last is the first again; the cache plays it back wrapping, for as long as the shot runs. 0 = a plain bake. Set the range's start; its end is ignored.
upres	Int	1	KQ-1's bake upres: the factor the bake's grid is finer than the live one (2 = twice the voxels per axis). Shape the shot live at a resolution that runs; the bake synthesises detail above the base grid's Nyquist with the same motion. 1 = off, which is every saved comp.
upres_octaves	Int	2	How many octaves of detail the upres synthesises above the base grid (each halves the scale). 2 is a bake that reads sharper without reading different.
upres_strength	Float	1.0	How strong the synthesised detail is against the base density. 1 = the detail at the base's own contrast; 0 = an upres that only interpolates.
start	Float	1.0	The shot's first frame of gas. Before it nothing draws. With preroll 0 the gas is one step old here (it was empty the frame before); with a preroll it is already up. To have gas at this frame, use preroll rather than an earlier start — the emitter window (emit_from) is a shot frame and would sit idle through the early frames.
preroll	Int	0	Frames simulated before start with the emitter running, off-screen, so the gas is already up when the shot begins — a start of 60 with preroll 30 runs frames 30–59 without showing them. 30 gives a chimney a full plume at its start; 0 starts from empty.
fps	Float	24.0	The shot's frame rate, so `buoyancy`, `drag`, rates and speeds are per SECOND and the look does not change with the project's fps.
emitter	Choice	sphere	The emitter's shape, placed in the domain's own space: a sphere, a box, or `matte` — the compositor's own: whatever is wired into the `matte` input (a Roto, a Crucible matte, any alpha) becomes the source, on a plane facing the camera-side z, `emit_radius` × 2 wide with the image's aspect, emitting through a slab `emit_soft` × 2 deep. Smoke comes off the roto's shape; an animated roto animates the source. `sphereboxmattejet`
jet_dir_x	Float	0.0	The Jet emitter's axis, x: the direction the cone of gas is fired along (a torch, a burner, a flamethrower). Normalised on use.
jet_dir_y	Float	1.0	The Jet emitter's axis, y. (0, 1, 0) fires straight up.
jet_dir_z	Float	0.0	The Jet emitter's axis, z.
jet_length	Float	1.0	How far the Jet's cone reaches along its axis, metres: `emit_radius` is the mouth at this distance and `emit_soft` is the nozzle at the source.
emit_x	Float	0.0	Emitter centre x, metres from the domain's floor centre.
emit_y	Float	0.3	Emitter centre height above the floor, metres.
emit_z	Float	0.0	Emitter centre z, metres from the domain's floor centre.
emit_radius	Float	0.25	The emitter's radius (sphere) or half-width (box), metres.
emit_soft	Float	0.1	Metres over which the emitter fades at its edge. 0 is a hard shape.
emit_density	Float	6.0	Smoke added per second inside the emitter. 0 emits heat alone — an invisible updraft.
emit_temperature	Float	1.0	The temperature the gas is pushed toward inside the emitter (0 = ambient). Heat is what makes it rise.
emit_heat_rate	Float	12.0	How fast the gas inside the emitter reaches `emit_temperature`, per second. High = an instant hot source; low = a slow warm-up.
emit_vx	Float	0.0	Velocity the emitter pushes the gas toward, x (m/s). With `emit_velocity_rate` 0 the emitter only adds material.
emit_vy	Float	0.0	Velocity the emitter pushes the gas toward, y — up (m/s). A jet.
emit_vz	Float	0.0	Velocity the emitter pushes the gas toward, z (m/s).
emit_velocity_rate	Float	0.0	How strongly the emitter imposes its velocity, per second. 0 = none; 10+ = a nozzle.
emit_fuel	Float	0.0	Fuel the emitter adds per second. 0 is a smoke or fog sim. Fuel is carried by the gas and burns where it is hot enough (`ignition`), into flames, heat and smoke — the Fire page sets how. The Torch, Campfire, Gas jet, Candle and Burning debris presets start from here.
emit_paint	Float	0.0	FS-9: the paint this source injects, 0 to 1 — the tracer colour. A voxel's paint is the density-weighted mix of what was there and what arrived, so two sources painting 0 and 1 meet in the middle. The Shading reads it through the ramp with `scatter_by` = paint; every emitter node has its own.
emit_color	Color	[1.0, 1.0, 1.0, 1.0]	RGB paint: the colour this source's gas carries. Where gases of different colours meet they mix like dye (density-weighted, per channel): red and blue make purple, blue and gold make green, with no ramp between them. White = undyed (and a sim where every source is white carries no dye at all). Seen with `scatter_by` = dye, where the colour IS the smoke's albedo; every emitter node has its own.
flammable	Bool	false	FS-8: the walls catch fire. Every wall this sim has — the plate's depth, a scene mesh, a placed box or sphere — lights where the gas beside it is hotter than `flammable_temp` for `flammable_dwell` frames; a lit cell injects fuel, heat and smoke for `flammable_fuel` seconds, and the fire spreads over the wall at `flammable_spread` cells a second, downwind of the gas. The KILN badge says how much burns. Off = the sim as it was.
flammable_temp	Float	0.6	The temperature the gas beside a wall cell must reach before the cell starts to catch (the solver's temperature units; a torch's core is 1).
flammable_dwell	Int	3	How many frames the gas must stay that hot beside a cell before it lights. A spark passing by does not; a torch held there does.
flammable_fuel	Float	3.0	How long a lit cell burns, seconds, before it is spent. Spent cells never relight.
flammable_spread	Float	6.0	How fast the fire runs over the wall: wall cells a second each burning cell lights. Half the time downwind of the gas, half anywhere, so fire climbs with an updraft and runs with a wind. 0 = only what the gas itself lights.
flammable_burn	Float	6.0	Fuel a second each burning cell injects into the gas beside it; the solver burns it into flames, heat and smoke as it burns any fuel (combustion, ignition, burn_rate).
flammable_heat	Float	1.0	The temperature a burning cell pushes the gas beside it toward.
flammable_smoke	Float	2.0	Density a second a burning cell injects — the smoke off the burning surface.
spray_rate	Float	0.0	The emitter's PARTICLES: splats a second born in the emitter's shape and riding the gas, each injecting its own small puff. 0 = off (a smooth field, which burns as one mass); above 0 the shape becomes the birth region and what emits is thousands of small splats — EmberGen's `Emitter: Particles`, and where their fire's structure comes from.
spray_life	Float	0.3	How long a spray particle lives, seconds, before it stops injecting.
spray_life_var	Float	0.35	How much the life varies per particle, as a fraction (0.35 = ±35%), so the spray dies raggedly instead of on one frame.
spray_radius	Float	0.02	The puff each spray particle injects, metres. Small against the emitter is what makes structure.
spray_radius_var	Float	0.4	How much the puff radius varies per particle, as a fraction.
spray_shrink	Float	0.0	How fast a particle's puff shrinks over its life (0 = constant; 1 = gone by the end).
spray_speed	Float	0.4	The speed a spray particle is born with, m/s, along `spray_dir` spread by `spray_spread`.
spray_dir_x	Float	0.0	The spray's birth direction, x. Normalised on use.
spray_dir_y	Float	1.0	The spray's birth direction, y. (0, 1, 0) = up.
spray_dir_z	Float	0.0	The spray's birth direction, z.
spray_spread	Float	1.0	How far off the birth direction the particles scatter (0 = a beam, 1 = a hemisphere).
spray_follow	Float	12.0	How hard a spray particle is pulled toward the gas's own velocity, per second. High = the particles are the gas; low = they carry their birth speed through it.
spray_gravity	Float	0.0	Gravity on the spray particles, m/s² downward. 0 = they ride the gas alone.
spray_drag	Float	0.5	How fast a spray particle's own speed decays, per second.
spray_max	Int	120000	The most spray particles alive at once. A cap on the cost; when it binds the oldest are dropped.
emit_from	Float	1.0	First frame the emitter is on.
emit_to	Float	1000000.0	Last frame the emitter is on. A short window makes a puff; leave it high for a steady source.
buoyancy	Float	4.0	Lift per unit of temperature above ambient, m/s² — the heat's pull upward. 4 is a lively plume; 1 is lazy.
weight	Float	0.1	How much smoke weighs, m/s² per unit of density: heavy smoke sinks and pools (fog); 0 neither sinks nor rises on its own.
vorticity	Float	0.3	Vorticity confinement: puts the small swirls back that the grid smooths away. 0.3 is natural; 1+ is ropey and turbulent.
drag	Float	0.05	Velocity lost per second. Kills momentum so the gas settles instead of coasting forever.
dissipation	Float	0.02	Smoke lost per second (fraction). 0 keeps every wisp; 0.1 clears fast.
cooling	Float	0.4	How fast heat returns to ambient, per second. High cooling: the plume stops rising soon after it leaves the source.
wind_x	Float	0.0	A steady wind the gas is pulled toward, x (m/s).
wind_y	Float	0.0	A steady wind, y — up (m/s).
wind_z	Float	0.0	A steady wind, z (m/s).
wind_coupling	Float	0.5	How strongly the gas follows the wind, per second. 0.5 is a breeze that lets the plume keep its own shape; 5 drags it bodily.
turbulence	Float	1.0	Curl-noise stirring, m/s². 0 is calm; 1–2 breaks a plume into billows. Divergence-free, so it never piles gas up.
turbulence_size	Float	0.5	The size of the turbulence's largest swirls, metres.
turbulence_speed	Float	0.5	How fast the turbulence pattern evolves, per second. 0 freezes it in space.
disturbance	Float	0.0	Disturbance (Pyro's Gas Disturb): a random push, in m/s², per block of `disturbance_size` metres, new every substep, where the gas is hotter than `disturbance_from` — high-frequency break-up of the flame's surface without changing its bulk motion. 2–4 for fire; 0 off.
disturbance_size	Float	0.15	The block size of the disturbance in metres — the scale of the break-up. 5 cm shreds a torch's surface; 20 cm churns a bonfire.
disturbance_from	Float	0.2	Disturbance acts where the temperature is above this (a soft gate a quarter of it wide), so the flame breaks up and the smoke above it is left alone. 0 acts wherever there is material.
shredding	Float	0.0	Shredding (Pyro's Gas Shred): the flow is turned along the temperature gradient at this rate per second, at its own speed — no speed added — which is the licking of flames at their tips. 2–4 for fire; 0 off. A weak gradient turns weakly.
shred_from	Float	0.1	Shredding acts where the temperature is above this (a soft gate a quarter of it wide). 0 acts wherever there is material.
sharpen	Float	0.0	Sharpening: anti-diffusion on the density at this rate per second — each voxel pulled away from its neighbours' mean, never below zero — so the smoke's edges hold against the advection's smear. 0.5–1 for defined smoke; 0 off.
seed	Int	7	The variation seed for the turbulence. Same seed, same gas.
pressure_iters	Int	40	Pressure solve passes per step. 40 is the look; fewer is faster and slightly puffier; more is exact.
floor	Bool	true	The floor is a wall: the gas cannot sink through it, so fog pools. Off, every face of the box is open.
combustion	Choice	simple	How fuel burns. `simple` burns fuel wherever it is hot enough — a glowing mass. `diffusion` burns at the INTERFACE where fuel meets air (an oxidiser field on both solvers; `stoich` sets how much air a unit of fuel needs): the wrinkled sheet a real flame is, and about 1.7% of the emission, so the fire look is re-dialled with it. `simplediffusion`
stoich	Float	10.0	Diffusion combustion: how much air a unit of fuel needs to burn. Higher makes the flame sheet thinner and further from the fuel.
burn_chaos	Float	0.0	Combustion chaos: the reaction rate wrinkled by a rising, vertically stretched noise, so the sheet burns in filaments instead of evenly. This is the knob that turns a lit shape into tongues. 0 = off.
burn_chaos_size	Float	0.15	The size of the combustion chaos's wrinkles, metres.
burn_chaos_speed	Float	1.5	How fast the combustion chaos rises through the flame, m/s.
ignition	Float	0.3	The temperature fuel must reach to burn (a soft gate a quarter of it wide). The emitter's own `emit_temperature` is what lights a torch; 0 burns fuel wherever it is.
burn_rate	Float	8.0	How fast lit fuel burns: the fraction of a voxel's fuel consumed per second. Faster is a shorter, hotter, crisper flame; slower fuel travels further before it burns.
heat_yield	Float	2.0	Heat per unit of fuel burnt, in temperature units (1 is the temperature `fire_kelvin` maps to). More lifts the flame harder and shifts its colour hotter.
smoke_yield	Float	0.25	Smoke (density) per unit of fuel burnt: 0 for a clean gas flame, 0.3 for a campfire, 0.8 for burning debris.
expansion	Float	0.5	How much burning gas pushes outward, as the divergence the pressure solve leaves per unit of fuel burnt per second. The whoomph of a fireball; 0 keeps the gas incompressible.
flame_life	Float	0.2	Seconds a flame lingers where nothing is burning any more (the `flames` field decays by e^(−t/life)). Short for a gas jet, longer for lazy licking flames.
fire_kelvin	Float	1800.0	The blackbody colour at temperature 1 (the emitter's `emit_temperature` scale), in kelvin: 1600 a sooty orange, 1900 a torch, 2600 a blue-white gas flame. Hotter voxels map beyond it.
fire_kelvin_ambient	Float	1000.0	The blackbody colour at temperature 0, in kelvin — the coolest a glowing voxel reads (the table starts at 1000 K, deep red).
fire_intensity	Float	4.0	Brightness of the flames at the reference temperature (`fire_kelvin`), scene-linear. With `fire_physical` on, hotter voxels are brighter by T⁴ from here; cooler ones dimmer.
fire_physical	Bool	true	Physically bright fire (KQ-3): the blackbody's radiance keeps its T⁴ magnitude relative to `fire_kelvin`, so an ember and the core differ by the orders of magnitude that are the fire look. Off: colour only, one brightness — the stylised reading.
fire_emit_low	Float	0.0	The flames' emit range, low end: where the `flames` field (fuel burnt per second) is below this nothing glows — the border of the flame gets crisp instead of fading out. 0 with `fire_emit_high` 0 leaves the field as it is.
fire_emit_high	Float	0.0	The flames' emit range, high end: above this the glow is flat at the high value — a flat bright core rather than a hot spot. Try 1 and 6 on a torch. 0 with `fire_emit_low` 0 leaves the field as it is.
fire_glow	Float	0.0	Fire lights its own smoke: the flames field IS a light, gathered over a small neighbourhood. 0 = off (the look every saved comp has); above it a torch in a dark room has orange smoke over it instead of black. The gain of that light.
fire_glow_radius	Float	0.15	How far the flames' glow reaches into the smoke, metres.
light_grid	Bool	false	The cached light grid (KQ-7): the shadow toward the key light and toward the sky is marched to the volume's edge from a coarse grid once per frame, instead of eight short steps at every sample. Shadows reach the whole volume and are soft; dense gas stops leaking light. Off keeps the look every saved comp has; the fog and smoke presets turn it on.
energy	Bool	false	FS-9's energy shading: the gas itself glows, through the four-stop ramp over the colour field (`ramp_by`) — no blackbody, no fuel. For spells, wisps, auras and portals. Set `smoke_albedo` to 0 alongside for glow alone; the presets do.
ramp_by	Choice	age	What the ramp reads: `age` — the age tracer, seconds since the gas was emitted (white where born, dark where old: trails); `temperature` — the heat; `density` — the gas itself (a two-tone core and halo). `agetemperaturedensitypaint`
ramp_low	Float	0.0	The colour field's value that reads as the ramp's first stop. Seconds for age, degrees for temperature, density for density.
ramp_high	Float	2.0	The colour field's value that reads as the ramp's last stop; between the two the four stops are evenly spaced, and past either end the ramp holds.
scatter_by	Choice	none	FS-9: the smoke's colour from a field through the four-stop ramp instead of the smoke colour: `paint` (what the sources injected — two paints mix where they meet), `age` (how long the gas has been out), `temperature` — or `dye`, the sources' own colours (`emit_color`) with no ramp at all: any number of colours mixing like dye. The ramp is the same one energy shading uses (ramp_0..3, ramp_low/high). The colour field rides the temperature slot, so on a burning sim the blackbody loses its temperature grid to it. `none` = the plain smoke colour. `nonepaintagetemperaturedye`
energy_intensity	Float	2.0	How bright the glow is per unit density, in the ramp's colours.
ramp_0_r	Float	1.0	The energy ramp: the first stop, at `ramp_low` — red.
ramp_0_g	Float	1.0	The energy ramp: the first stop, at `ramp_low` — green.
ramp_0_b	Float	1.0	The energy ramp: the first stop, at `ramp_low` — blue.
ramp_1_r	Float	0.45	The energy ramp: the second stop, a third of the way up — red.
ramp_1_g	Float	0.8	The energy ramp: the second stop, a third of the way up — green.
ramp_1_b	Float	1.0	The energy ramp: the second stop, a third of the way up — blue.
ramp_2_r	Float	0.55	The energy ramp: the third stop, two thirds up — red.
ramp_2_g	Float	0.2	The energy ramp: the third stop, two thirds up — green.
ramp_2_b	Float	1.0	The energy ramp: the third stop, two thirds up — blue.
ramp_3_r	Float	0.05	The energy ramp: the last stop, at `ramp_high` — red.
ramp_3_g	Float	0.0	The energy ramp: the last stop, at `ramp_high` — green.
ramp_3_b	Float	0.12	The energy ramp: the last stop, at `ramp_high` — blue.
unlit_ambient	Float	1.0	The flat light on the gas when the scene has NO lights. 1 = what shipped: a white sky that is not there, which on a fire in a dark scene lights the thin smoke into a grey halo. The fire and energy presets run 0, so only the flame lights its own smoke. Inert once the scene has a light.
fire_opacity	Float	0.0	How much the FLAMES field extinguishes light. 0 = fire as a purely additive emitter, which cannot hide its own core, so a thick flame integrates into a saturated mass with no dark interior. Above 0 only the near surface glows and the inside goes dark behind it — the translucent-sheet look of EmberGen's default fire.
ms_octaves	Int	0	Wrenninge's octave multiple scattering, under Karma's knob names. Octaves of scattering beyond the first: 0 = single scatter (what shipped), 2–3 = thick smoke bright in the middle and soft at its edge instead of a dark mass with a lit rim. Nearly free.
ms_extinction	Float	0.5	Multiple scattering: each octave sees the medium thinner by this factor (Karma's extinction modifier). 0.5 is the usual.
ms_contribution	Float	0.5	Multiple scattering: each octave contributes this fraction of the one before (Karma's contribution modifier). Raise it to bring Live's interior brightness toward Final's.
ms_phase	Float	0.5	Multiple scattering: each octave scatters more broadly by this factor on the anisotropy (Karma's phase modifier).
sky_occlusion	Float	0.0	A dome light occluded by the gas above a voxel — what makes a fog bank darker underneath than on top. 0 = the flat ambient fill every saved comp has; 1 = the sky fully shadowed by the gas above. With `light_grid` on, the occlusion is marched to the volume's edge.
renderer	Choice	live	live: the raymarch (what the viewport draws, what every saved comp has). final: the Final renderer — a volumetric path tracer over the same gas, lights and look: no step size, every light sampled directly with an exact transmittance, real multiple scattering up to `bounces`, a dome occluded by the gas above. Slower by `spp`; deterministic. The bake renders with it too. `livefinal`
spp	Int	16	Final renderer: samples a pixel a render. 16 is a look-dev preview with grain; 64–256 is a frame worth keeping. The cost is linear in it.
bounces	Int	4	Final renderer: how many times light may scatter inside the gas. 1 is single scattering (the march's model, exactly integrated); 4–8 lights the inside of thick smoke and softens its edges the way a film volume renderer does.
pt_seed	Int	0	Final renderer: the noise pattern's seed. The frame number is added, so no two frames share their noise and the same frame renders the same twice.
denoise	Choice	off	Cleans a Final render's noise, on the SCATTERED light only (the fire, the alpha and the depth are never touched). `ai` = Intel Open Image Denoise: clean frames at a fraction of the samples, on the GPU where it can; where its library is not installed it falls back to `spatial` and the panel says so. `spatial` = an edge-aware à-trous filter, the same answer every run. Off by default. `offspatialai`
denoise_passes	Int	3	How wide the denoise reaches: à-trous passes, 1 (a 5×5) to 6 (the whole frame). 3 is the usual.
march_step	Float	1.5	How far the viewport's march steps, in voxels. 1.5 is what shipped and is coarse (it undersamples the grid); 0.75 is the presets'; under 1 costs proportionally and is what a final frame wants. The Final renderer has no step.
sharpen_smoke	Float	0.0	Raymarch sharpening (EmberGen's name): an unsharp mask on the density as it is SAMPLED, so a grid too coarse to hold an edge still renders one. Their default fire runs all three at 2.5. 0 = off.
sharpen_flames	Float	0.0	Raymarch sharpening on the flames field as it is sampled: crisper tongues from the same grid. 0 = off.
sharpen_temperature	Float	0.0	Raymarch sharpening on the temperature field as it is sampled: crisper colour edges in the fire. 0 = off.
sharpen_radius	Float	1.0	The raymarch sharpening's tap radius, voxels. 1 sharpens the finest edges; larger sharpens broader structure.
smoke_albedo	Float	0.7	How much light the smoke scatters back: 0.7 is grey-white fog and steam, 0.4 a campfire's smoke, 0.12 the soot off burning debris. A VolumeShade wired after the Kiln overrides the whole look.
density_scale	Float	1.0	How much one unit of density extinguishes light, per metre (`units` world) or per voxel. The first dial for how thick the gas reads; the shadows and the alpha follow it.
anisotropy	Float	0.2	The scattering's forward bias (Henyey-Greenstein g), −0.9 to 0.9. 0 scatters evenly; 0.2–0.5 is smoke, brighter toward the light behind it; negative scatters back.
shadow_density	Float	1.0	How hard the gas shadows itself: the density seen by the shadow toward the key light and the sky, as a multiple of `density_scale`. Under 1 lets light deeper in than the alpha says; an art-direction dial.
embers	Float	0.0	Embers born per second in the flames — sparks that ride the gas up and out, glowing, cooling and dying. 0 is off. 40 for a campfire, 60 for burning wreckage, a dozen for a torch. Drawn as glowing dots with the gas, in the viewport and the render; a bake writes them beside its frames (`<label>.embers.json`) and plays them back.
ember_from	Float	2.0	Embers are born where `flames` (fuel burnt per second) is above this, weighted by how hard the voxel burns. Higher keeps them to the fire's core.
ember_life	Float	1.5	Seconds an ember lives, give or take `ember_life_var` of it.
ember_life_var	Float	0.5	How much lives vary, 0–1 of `ember_life`: 0 is a uniform lifetime, 0.6 a spread from short flickers to long travellers.
ember_kick	Float	1.5	The upward kick at birth, m/s, on top of the gas's own velocity — how far an ember leaps out of the flame before the gas takes over.
ember_follow	Float	4.0	How fast an ember's motion is pulled toward the gas's (1/s): high and it is carried like smoke, low and it flies its own arc.
ember_gravity	Float	1.0	Downward pull on the embers, m/s². Light ash rises on the gas at 0.5; a heavy cinder falls at 3.
ember_drag	Float	0.5	Velocity lost per second. More settles an ember into the gas sooner.
ember_cool	Float	0.8	Heat lost per second: 1 → white-hot at birth, cooling through orange to dark. Faster and they wink out; slower and they trail glowing.
ember_glow	Float	6.0	Brightness at full heat, scene-linear; it falls with the square of the heat as an ember cools.
ember_kelvin	Float	1800.0	The blackbody colour at full heat; an ember cools toward the table's deep red at 1000 K.
ember_size	Float	3.0	Dot size on screen, pixels — constant at any distance (the point-cloud dot path).
ember_max	Int	4000	The most embers alive at once; the oldest die first past it. A cap so a long shot cannot quietly grow unrenderable.
ember_seed	Int	11	The embers' own seed: the same seed, gas and frame birth the same embers, live, on a resume from a checkpoint and in a bake.
units	Choice	world	What one unit of density means to the renderer: `world` integrates per metre (the physical reading, the default for a new node); `voxel` per index voxel. `voxelworld`
network	Text		The sim network inside this node — Domain, Solver, emitters, forces, Input and Output nodes wired into typed ports — as one value (dive in to edit it; never a text field). Empty is the default network: this panel's sections as nodes, every knob promoted to the panel. An inner knob set inside beats the panel; a promoted one follows it.
bake_dir	Text		Where ⚒ Bake writes its frames. Empty keeps every project in its own folder (`kiln/<project>` beside the script); point it anywhere for a shared cache. The frames are `.vdb` files any DCC opens.
bake_label	Text		What the baked frames are called (`<label>.####.vdb`). Empty uses the node's name. A manifest beside them names the bake's owner, so another node pointed at the same files never plays a mix of two sims.
bake_grids	Choice	density temperature	Which grids a bake writes per frame: `density` alone; `density temperature` (the default — what the shading reads); or with `vel` too — the velocity as one vec3 grid, the way Houdini's and Karma's motion blur read it. Half precision, zip-compressed; more grids, bigger files. `densitydensity temperaturedensity temperature velocitydensity temperature agedensity temperature velocity agedensity temperature paintdensity temperature velocity age paint`
baked	Text		The last bake's frame pattern. While its fingerprint still matches the sim, the node plays from these files instead of simulating — at speed, whatever the sim weighs, and scrubbing is free. A sim knob change makes it stale (the badge says so) and the sim runs live again; the re-bake is your click, never a silent re-sim. Clear bake goes live and leaves the files.
baked_hash	Text		The spec fingerprint the bake was simulated from — every sim knob, the emitters, the forces, the domain. Shading and render knobs are not in it, so a look change never stales the volume cache: bake the motion, keep shading live.
baked_range	Text		The frames the bake covers. Outside them the sim runs live.
baked_loop	Text		Written by the Bake: the loop length the frames on disk close over, or empty for a plain bake. The cook wraps playback by it.
disabled	Bool	false	Bypass: the node passes its first input through untouched (D in the graph). The knobs keep their values for when it comes back.
label	Text		A note shown under the node in the graph — what this node is FOR. Never affects the render or the cache.
hide_input	Bool	false	Draw the node without its input wire — a tidy graph for a node whose source is obvious (a Dot, a viewer tap).