ANR 3D scene fire: ANR Tools docs

Overview

Scene Fire sets fire to the 3D scene behind your plate. Connect geometry or particles to Source and your shot camera to Camera, and the node imports a frame range of them into Studio, a separate editor window. There you choose what burns and what blocks the smoke, add lights and forces, and simulate. Save & Exit in Studio publishes the result back to the node, and Nuke renders the saved fire and smoke through the camera.

Use it when the fire has to come from the scene itself: a burning car from its model, flames over an object's surface or from a particle system, smoke that wraps around a building. Catchers geometry receives the smoke's shadows and the fire's light as layers you can comp, and can block the simulation.

Simulation happens only in Studio. In Nuke the node plays the published result, so scrubbing and rendering never re-simulate, and the Look, Light, Render, Transform and Camera tabs change only the picture. Edits to the scene upstream go into Studio with Update from Nuke.

Everything the node imports and simulates lives in its Project folder, which you set first. Bullet Time freezes the published fire on one frame while the camera, the lights and the look keep moving.

Inputs

Footageoptional
The plate. Studio shows it behind the scene through the scene camera so you can line things up, and Output view can show it; it is never baked into the fire. Show footage input adds a labelled connector for it.
Sourcerequired
What emits: geometry (a mesh, a ReadGeo, a Card or a Sphere), a particle system, or a Scene joining both. Mesh texture alpha and particle opacity scale the emission. Particle sources need NukeX or Nuke Studio.
Cameraoptional
Your shot camera, a perspective Camera with default window controls. Studio imports it, and after Save & Exit Nuke renders the fire through it, so the effect lines up with the plate.
Environmentoptional
Optional linear latitude-longitude HDR image, imported into Studio for broad ambient light on the smoke.
Catchersoptional
Optional geometry that catches the effect: by default it collides with the simulation, hides the fire behind it and receives the smoke's shadows and the fire's light (the Shadow and Fire light layers). Show catcher connector adds a labelled connector for it.

Output. RGBA of the published fire and smoke, transparent around it, ready to merge over the plate. Render > Output & layers adds named layers (fire, smoke, shadow, fire light and more) beside the beauty. Output view settings other than Simulation add the footage or the model, for checking only.

Quick start

Add ANR 3D scene fire and set Project folder on the Studio tab first.
Connect what burns to Source, your shot camera to Camera and the plate to Footage (Show footage input adds a connector). Environment and Catchers are optional.
Set First frame and Last frame: the range Studio imports, at most 2,001 frames.
Click Open UI. The range is imported, with a progress bar, and Studio opens in its own window.
In Studio, choose which objects are sources and which are collisions, add lights and forces, set up the simulation and simulate.
Click Save & Exit in Studio. The node plays the result in Nuke, and Status shows its frame range.
Grade on Look and Light, turn on the layers you need on Render, and merge the result over the plate. Keep Output view on Simulation for the final.
After changing the scene, the camera or the plate in Nuke, click Update from Nuke to bring the changes into Studio, then simulate again.

The panel

The node's panel as Nuke shows it, with the values of a new node. Click any control to see what it does; tabs and sections work as in Nuke.

ANR_3D_scene_fire1

Bullet Time, the project folder, Output view, opening Studio, updating from Nuke, the import range and the mesh sampling.

Bullet TimeFreeze at1

Project folder

Project FPSroot.fps

Set Project folder first. Connect Footage, Source and Camera, then Open UI.
Source accepts geometry, particles or a Scene containing both. Optional: Environment and Catchers geometry. Create lights inside Studio.
The selected frame range is imported once. Studio playback and simulation run independently.
Save & Exit publishes the result for Nuke rendering. Update from Nuke reimports changed inputs.

Open UIUpdate from NukeLoad saved editor resultShow catcher connectorShow footage input

Connect your Read / plate to Footage, then Update from Nuke.

StatusConnect catcher geometry to the right-hand connector, then Update from Nuke.

Import settings
Geometry exports as animated Alembic. Camera, particles and footage are cached for independent editing.
Set the range, then Open UI. Use Update from Nuke after upstream edits.

First frame1

Last frame100

Surface samples20000Use mesh texture alpha

Texture cache size1024

All controls

Studio16 controls

Bullet Time, the project folder, Output view, opening Studio, updating from Nuke, the import range and the mesh sampling.

Bullet TimeCheckboxbulletTime

Freezes the simulation at the Freeze at frame. The camera, the volume transform, the lights and the look keep following the timeline, so you can fly around the frozen fire. Holding a frame costs no simulation time. Ticking it freezes at the current frame. Animate it off to let the simulation go on. Works live and on Read cache.

Default: off

Freeze atSliderbulletFrame

The simulation frame Bullet Time holds. Before it the simulation plays normally; from it on the fire stays still. Animatable.

Default: 1

Project folderFilecaptureFolder

Required. Scene assets, editor project and simulation caches live beneath this folder.

Default: empty

Project FPSSliderstudioFps

The script's frame rate, which Studio plays and simulates at.

Default: root.fps

Output viewMenuviewerDisplay

Viewing helper. Simulation preserves the normal transparent output and layers. Other modes include the connected footage/model in the output; choose Simulation for final passes. Models use the connected Nuke geometry/camera, before Studio edits.

Default: SimulationOptions: Simulation Footage Model Simulation over footage Model over footage Full preview

Open UIButtonopenStudio

Imports the First frame to Last frame range of the connected inputs into the project folder, the first time or where frames are missing, then opens Studio. Studio then works on its own: it does not move Nuke's timeline or ask Nuke to render.

Update from NukeButtonupdateStudio

Imports the inputs again after you changed them upstream (or changed the frame range), then opens Studio. A cancelled import keeps the previous project and result.

Load saved editor resultButtonapplyStudio

Loads the last result saved with Save & Exit in the project folder into this node, without simulating.

Show catcher connectorButtonshowCatcherInput

Adds a labelled connector beside the node, wired to the Catchers input, to plug catcher geometry into.

Show footage inputButtonshowFootageInput

Adds a labelled connector beside the node, wired to the Footage input, to plug your Read or plate into.

StatusStatusstudioStatus

What the node and Studio are doing: importing, Studio open, or the frame range of the saved result that plays.

First frameSlidercaptureFirst

First frame of the range imported into Studio.

Default: 1

Last frameSlidercaptureLast

Last frame of the range imported into Studio, at most 2,001 frames after First frame.

Default: 100

Surface samplesSlidermeshSamples

Samples per captured frame, shared across the connected mesh surfaces. Increase for fine texture alpha or large surfaces. Changes need Update from Nuke. Maximum 250,000.

Default: 20000

Use mesh texture alphaCheckboxuseMeshAlpha

Cache the direct image input on Cube, Sphere, Cylinder or Card and sample its alpha using Alembic UVs. Material/shader networks inside merged geometry are not transferred. Turn off for opaque emission.

Default: on

Texture cache sizeSlidermeshTextureSize

Maximum texture edge in pixels. 1024 is fast; increase for fine masks, or 0 for original resolution. Caches linear 16-bit RGBA PNG once on import; fast compression runs outside Nuke. Changes need Update from Nuke.

Default: 1024

Advanced playback3 controls

GPU scheduling and what plays after the last published frame.

GPU schedulingMenugpuScheduling

Responsive leaves GPU time for the desktop. Maximum speed removes deliberate pauses and uses larger batches; desktop interaction may slow while calculating. Simulation quality is identical.

Default: ResponsiveOptions: Responsive Maximum speed

After last frameMenucacheAfter

What plays after the last cached or Studio frame: that frame held still, or nothing. Held frames keep render-only detail still.

Default: EmptyOptions: Hold last frame Empty

studioAdvancedEnd

StatusStatusbackendInfo: What Nuke's playback is doing: which saved frame plays, or why a frame shows nothing.

Look12 controls

Smoke density and colour, flame brightness and colours, without re-simulating.

Smoke

Smoke densitySlidersmokeDensity

Flow render density multiplier. Increase for thick soot without re-simulating; combine with a dark smoke color.

Default: 0.6

Smoke colorColoursmokeColor

Colour of the smoke. Dark values give sooty black smoke, still lit by the fire.

Default: 0.2399999946 0.2450000048 0.25

AbsorptionSlideropacity

Absorption along real paths through the smoke.

Default: 5

Fire

Flame brightnessSliderfireIntensity

Emission integrated within the smoke volume.

Default: 6.4

Fire colorMenufireColorMode

Blackbody uses the cool/hot temperatures in Kelvin. Custom gradient uses the three color swatches below. Both share saturation and color bias.

Default: BlackbodyOptions: Blackbody Custom gradient

Fire saturationSliderfireSaturation

Flow flame color saturation; 0 is neutral and 1 preserves the chosen colors.

Default: 1

Fire color biasSliderfireColorBias

Flow color-gradient distribution. Above 1 favors the cool flame color; below 1 favors the hot color.

Default: 2.33

Flame colors

Cool temperature (K)SliderkelvinMin

Blackbody color at the low end of the temperature range.

Default: 1000

Hot temperature (K)SliderkelvinMax

Blackbody color at the high end of the temperature range.

Default: 5100

Custom coolColourfireCool

With Fire color set to Custom gradient: the colour of the coolest flame, at the tips.

Default: 1 0.02500000037 0.002000000095

Custom midColourfireMid

With Custom gradient: the colour in the middle of the flame's temperature range.

Default: 1 0.2199999988 0.009999999776

Custom hotColourfireHot

With Custom gradient: the colour of the hottest flame, in the core.

Default: 1 0.8999999762 0.5500000119

Temperature mapping1 control

Which simulated temperature gets the hottest flame colour.

Temperature rangeSlidertemperatureRange

Simulation temperature mapped to the hottest flame color.

Default: 1.25

Light9 controls

Sky light, the fire's light inside the smoke, ambient and key light.

Sky intensitySliderskyIntensity

Smoke illumination from the upper sky dome. Density along each light ray occludes the sky. 0 is off and preserves previous renders; render-only.

Default: 0

Sky colorColourskyColor

Colour of the sky light set by Sky intensity.

Default: 0.6999999881 0.8000000119 1

Sky samplesSliderskyLights

Directions over the sky dome (Flow). Higher values soften directional sampling at extra render cost. Does not re-simulate. Legacy uses six directional lobes.

Default: 8

Internal fire light

Fire illuminationSliderfireLight

Flow: colored flame light propagated through a sparse volume with absorption and approximate multiple scattering. Strength is independent of visible flame brightness.

Default: 0.9

Light spreadSliderfireLightRadius

Spread of diffuse fire illumination as a fraction of domain width.

Default: 0.1

Light penetrationSliderscattering

Diffuse light penetration into smoke. Flow reduces effective absorption when propagating multiply scattered fire light; this is a diffusion approximation.

Default: 0.7

Scene lighting

Ambient fillSliderambient

Environment illumination.

Default: 0

Key lightSliderkeyLight

Directional light with volume self-shadowing.

Default: 1

Ambient occlusionSliderambientOcclusion

Shadows within the volume under environment lighting.

Default: 1

Light direction4 controls

Direction of the key light and how strongly the smoke scatters it forward.

Key direction XSliderlightX

Direction toward the light.

Default: -0.6

Key direction YSliderlightY

Direction toward the light.

Default: 0.8

Key direction ZSliderlightZ

Direction toward the light.

Default: 0.7

Forward scatterSlideranisotropy

Directionality of scattering: 0 is isotropic, positive favors backlighting.

Default: 0.15

Environment map7 controls

The environment light, the brightness of the scene lights made in Studio, and the catcher shadows.

Use environmentCheckboxuseEnvironment

Connect a linear latitude-longitude HDR/EXR image to Environment. Flow adds broad ambient color; environment rotation and directional map lighting require Legacy OpenCL. Alpha is ignored and the background stays transparent.

Default: on

IntensitySliderenvironmentIntensity

Brightness of the connected linear latitude-longitude environment map.

Default: 1

ExposureSliderenvironmentExposure

Environment exposure in stops; +1 doubles the light.

Default: 0

Rotation YSliderenvironmentRotation

Rotate environment lighting around the volume's vertical axis, in degrees.

Default: 0

Scene light gainSlidersceneLightGain

Brightness of captured 3D lights. Render-only. Point/spot falloff uses Nuke scene units; no scene geometry shadowing, smoke self-shadowing only.

Default: 1

Shadow smoke densitySlidercatcherDensity

Smoke density used only for catcher shadows. Independent from visible smoke density; lower values reveal lighter, finer shadows without changing beauty.

Default: 0.6

Shadow softness (degrees)SlidercatcherSoftness

Angular spread of the catcher shadow rays. 0 is sharp; increase to soften smoke shadows. Render-only; does not blur receiver alpha or change beauty.

Default: 0

Render22 controls

Render quality, the extra layers, render-time detail and distortion, smoothing, projection and the view.

Render qualityMenurenderQuality

Render is full quality. Preview uses the same fast native volume renderer as Studio: cubic filtering at 320 pixels, without expensive lighting/detail passes. Output stays linear; the Nuke Viewer controls its display transform.

Default: RenderOptions: Preview Render