Purpose

Path Trace renders a Scene, with its geometry, Materials, lights and camera, to a beauty image and nine guide images. It is the progressive reference renderer. For a picture you watch in motion, start with Realtime Trace. Reach for Path Trace when you want a still view to converge over many frames.

Use

Place Path Trace in the Geometry view of the Voro menu, under Render. On its Scene page, set Scene to a Scene and Scene Mode to Scene. For a quick render without a separate Scene, choose Local and set Geometry, Lights and Camera on Path Trace itself. Camera takes a Camera operator or a native Camera COMP. Lights takes Light operators and native Light COMPs.

Path Trace opens at 1920 by 1080 with one sample per frame and four bounces. Pick another size from Preset or type it into Resolution. For a still view, turn on Accumulate and let the picture converge.

Inputs and outputs

scene takes the collected scene, including its Sky. Connect an HDR environment image to Sky’s hdr input and select HDR there.

beauty is the picture. The other nine outputs are guides: depth, normal, albedo, motion, specular albedo, specular hit distance, fresh_beauty, view_depth and motion_reset. Realtime Trace publishes the same ten outputs with the same meaning.

Every output is a GPU float32 image with the bottom row first. Display Transform applies to beauty only. fresh_beauty and the guides stay linear.

Controls

• Scene Mode offers Local, Scene and Scene + Local. Scene uses the linked Scene and disables the local selectors. Scene + Local combines both selections, removes duplicates and keeps the Scene’s entries first.
• In Scene + Local, a local Camera overrides the Scene’s camera. With the Scene field empty, the local selectors work in every mode. A Scene field that names something other than a Scene, or no camera at all, stops the render with an error.
• Resolution sets the render size, up to 8192 on each axis. Nothing else sets it. Preset only fills in the two Resolution values.
• Samples Per Frame and Max Bounces set how much work each frame does. Raising either costs render time.
• Accumulate converges a still view, and Reset Accumulation starts it over. Keep Accumulate off while you judge motion.
• Exposure multiplies the linear image. 1 leaves it unchanged. It is not measured in stops.
• Display Transform is ACES by default. When beauty feeds Reconstruct or a compositing chain with its own view transform, set it to Linear and apply the transform once, on the output you look at.
• Select a Sky on the Scene’s Collection page, or on Path Trace’s Scene page in Local mode. In Scene + Local, a local Sky overrides the Scene’s Sky. Without a selected Sky, the Environment page’s Fallback Sky supplies a procedural sky and sun. Sun Direction points toward the sun.
• Emissive Sampling picks which glowing triangle each light sample tries. The default, tree, favours emitters that are near and facing the surface, which cuts grain in a scene with many small emitters.
• The Points and Lines pages set how point and curve geometry draws: a radius for points, and a tube radius and colours for curves.

Notes

Every light in Voro uses one unit. Intensity 1 makes a white surface facing the light read 1.0 at Exposure 1. For a point or spot light that reading is at 1 world unit, falling off with the square of the distance beyond it. A spot light 30 units above the ground needs about 900 to light it as brightly as a sun of 1.

Path Trace draws authored Material looks in a normal install. After a graphics driver update, the next render waits while the renderer prepares itself again, which takes around ten minutes. Status shows the progress. A bad Material edit keeps the last valid image and reports the error.

A few things render differently from Realtime Trace:

• Motion blur and the Lens page belong to Realtime Trace.
• A look keyed to the object’s own space follows a moving object in Realtime Trace. In Path Trace that pattern sits in world space, so the object moves through it.
• Looks that draw outlines show none in Path Trace, which has no finished frame of neighbouring pixels to find edges in.

Path Trace has no denoiser of its own. Pulse Add Reconstruct on the Output page to put a Reconstruct behind it.

Ports

Inputs

• scene scene required

Outputs

• beauty image required
  RGBAlinear
• depth image required
  single channel
• normal image required
  RGBA
• albedo image required
  RGBA
• motion image required
  2 channels
• specular_albedo image required
  RGBA
• specular_hit_distance image required
  single channel
• fresh_beauty image required
  RGBA
• view_depth image required
  single channel
• motion_reset image required
  single channel

Parameters

Output

Resolution (Resolution1) Int op('path_trace').par.Resolution1

Default:

1920

Range:

1 to 8192

Resolution (Resolution2) Int op('path_trace').par.Resolution2

Default:

1080

Range:

1 to 8192

Preset (Preset) Menu op('path_trace').par.Preset

Default:

2

Options:

Custom, HD 1280x720, Full HD 1920x1080, QHD 2560x1440, UHD 3840x2160, Square 1080x1080, Square 2048x2048, Portrait 1080x1920, Portrait UHD 2160x3840

Accumulate (Accumulate) Toggle op('path_trace').par.Accumulate

Default:

Off

Options:

Off, On

Display Transform (Displaytransform) Menu op('path_trace').par.Displaytransform

Default:

1

Options:

Linear, ACES

Reset Accumulation (Resetaccumulation) Pulse op('path_trace').par.Resetaccumulation

Default:

None

Exposure (Exposure) Float op('path_trace').par.Exposure

Default:

1

Range:

0 to 8

Points

Fallback Radius (Pointradius) Float op('path_trace').par.Pointradius

Default:

0.01

Range:

0 to 10

Radius Scale (Pointscale) Float op('path_trace').par.Pointscale

Default:

1

Range:

0 to 10

Integrator

Max Bounces (Maxbounces) Int op('path_trace').par.Maxbounces

Default:

4

Range:

1 to 16

Samples Per Frame (Samplesperframe) Int op('path_trace').par.Samplesperframe

Default:

1

Range:

1 to 64

RR Start Bounce (Rrstartbounce) Int op('path_trace').par.Rrstartbounce

Default:

3

Range:

0 to 16

Clamp Radiance (Clampradiance) Float op('path_trace').par.Clampradiance

Default:

10

Range:

0.1 to 100

NEE Samples (Neesamples) Int op('path_trace').par.Neesamples

Default:

1

Range:

1 to 16

NEE Clamp (Neeclamp) Float op('path_trace').par.Neeclamp

Default:

10

Range:

0.1 to 100

MIS (Mis) Toggle op('path_trace').par.Mis

Default:

On

Options:

Off, On

VNDF Sampling (Vndf) Toggle op('path_trace').par.Vndf

Default:

On

Options:

Off, On

Smith G (Smithg) Toggle op('path_trace').par.Smithg

Default:

On

Options:

Off, On

Glass Model (Glassmodel) Menu op('path_trace').par.Glassmodel

Default:

0

Options:

legacy, ggx

Hero Channel Mode (Herochannel) Menu op('path_trace').par.Herochannel

Default:

1

Options:

random, stratified

Sampler Pattern (Samplerpattern) Menu op('path_trace').par.Samplerpattern

Default:

0

Options:

white, sobol, bluenoise

Jitter Phases (Jitterphases) Int op('path_trace').par.Jitterphases

Default:

32

Range:

0 to 128

Direct Lighting (Directlighting) Toggle op('path_trace').par.Directlighting

Default:

On

Options:

Off, On

Emissive Sampling (Emissivesamp) Menu op('path_trace').par.Emissivesamp

Default:

2

Options:

uniform, powercdf, tree

ReSTIR Candidates (Restircandidates) Int op('path_trace').par.Restircandidates

Default:

1

Range:

0 to 32

Spatial Reuse (Spatialreuse) Toggle op('path_trace').par.Spatialreuse

Default:

Off

Options:

Off, On

Reuse Neighbors (Reuseneighbors) Int op('path_trace').par.Reuseneighbors

Default:

0

Range:

0 to 16

Reuse Radius (Reuseradius) Float op('path_trace').par.Reuseradius

Default:

1

Range:

0 to 16

Temporal Reuse (Temporalreuse) Toggle op('path_trace').par.Temporalreuse

Default:

Off

Options:

Off, On

Temporal M Cap (Temporalmcap) Int op('path_trace').par.Temporalmcap

Default:

20

Range:

1 to 64

Style

Dispersion Fallback (Dispersion) Float op('path_trace').par.Dispersion

Default:

0

Range:

0 to 1

Dispersion Hype (Dispersionhype) Float op('path_trace').par.Dispersionhype

Default:

1

Range:

0 to 16

Dispersion Softness (Dispersionsoftness) Float op('path_trace').par.Dispersionsoftness

Default:

0.35

Range:

0 to 1

Shadow Tint (Shadowtintr) Float op('path_trace').par.Shadowtintr

Default:

1

Range:

0 to 1

Shadow Tint (Shadowtintg) Float op('path_trace').par.Shadowtintg

Default:

1

Range:

0 to 1

Shadow Tint (Shadowtintb) Float op('path_trace').par.Shadowtintb

Default:

1

Range:

0 to 1

Emission Hype (Emissionhype) Float op('path_trace').par.Emissionhype

Default:

1

Range:

0 to 32

Emissive Refl Clamp (Emissivereflclamp) Float op('path_trace').par.Emissivereflclamp

Default:

0

Range:

0 to 100

Spectral Force (Spectralforce) Toggle op('path_trace').par.Spectralforce

Default:

Off

Options:

Off, On

Caustic Intensity (Causticintensity) Float op('path_trace').par.Causticintensity

Default:

0

Range:

0 to 8

Caustic Spread (Causticspread) Float op('path_trace').par.Causticspread

Default:

0.5

Range:

0 to 1

Caustic Tint (Caustictintr) Float op('path_trace').par.Caustictintr

Default:

1

Range:

0 to 1

Caustic Tint (Caustictintg) Float op('path_trace').par.Caustictintg

Default:

1

Range:

0 to 1

Caustic Tint (Caustictintb) Float op('path_trace').par.Caustictintb

Default:

1

Range:

0 to 1

Lines

Line Look (Look) Menu op('path_trace').par.Look

Default:

0

Options:

lit, toon, energy

Tube Radius (Radius) Float op('path_trace').par.Radius

Default:

0.08

Range:

0.0001 to 1

Radius Mode (Radiusmode) Menu op('path_trace').par.Radiusmode

Default:

1

Options:

fixed, pervertex

Color Mode (Colormode) Menu op('path_trace').par.Colormode

Default:

1

Options:

uniform, fromcolor

Albedo / Low (Albedor) Float op('path_trace').par.Albedor

Default:

0.55

Range:

0 to 1

Albedo / Low (Albedog) Float op('path_trace').par.Albedog

Default:

0.72

Range:

0 to 1

Albedo / Low (Albedob) Float op('path_trace').par.Albedob

Default:

1

Range:

0 to 1

Ramp High (Colorbr) Float op('path_trace').par.Colorbr

Default:

1

Range:

0 to 1

Ramp High (Colorbg) Float op('path_trace').par.Colorbg

Default:

0.45

Range:

0 to 1

Ramp High (Colorbb) Float op('path_trace').par.Colorbb

Default:

0.12

Range:

0 to 1

Emissive Color (Emiscolorr) Float op('path_trace').par.Emiscolorr

Default:

0.3

Range:

0 to 1

Emissive Color (Emiscolorg) Float op('path_trace').par.Emiscolorg

Default:

0.7

Range:

0 to 1

Emissive Color (Emiscolorb) Float op('path_trace').par.Emiscolorb

Default:

1

Range:

0 to 1

Glow (Emisint) Float op('path_trace').par.Emisint

Default:

1.4

Range:

0 to 8

Arc Flow Speed (Flowspeed) Float op('path_trace').par.Flowspeed

Default:

0.25

Range:

0 to 4

Roughness (Roughness) Float op('path_trace').par.Roughness

Default:

0.35

Range:

0 to 1

Metallic (Metallic) Float op('path_trace').par.Metallic

Default:

0

Range:

0 to 1

Cull Off-Screen (Linecull) Toggle op('path_trace').par.Linecull

Default:

Off

Options:

Off, On

Cull Sub-Pixel (Linecullpx) Float op('path_trace').par.Linecullpx

Default:

0.5

Range:

0 to 4

Cull Hold Frames (Linecullhold) Int op('path_trace').par.Linecullhold

Default:

8

Range:

1 to 120

Advanced

Shadow Ray Mode (Shadowraymode) Menu op('path_trace').par.Shadowraymode

Default:

2

Options:

anyhit, closesthit, hybrid

Light Shadow Bypass (Lightshadowbypass) Toggle op('path_trace').par.Lightshadowbypass

Default:

Off

Options:

Off, On

Emissive Double Sided (Emissivedoublesided) Toggle op('path_trace').par.Emissivedoublesided

Default:

Off

Options:

Off, On

Normal Map Enable (Normalmapenable) Toggle op('path_trace').par.Normalmapenable

Default:

On

Options:

Off, On

Normal Map Strength (Normalmapstrength) Float op('path_trace').par.Normalmapstrength

Default:

1

Range:

0 to 4

Environment

Fallback Sky (Envenabled) Toggle op('path_trace').par.Envenabled

Default:

On

Options:

Off, On

Sun Direction (Sundirx) Float op('path_trace').par.Sundirx

Default:

0.2

Range:

-1 to 1

Sun Direction (Sundiry) Float op('path_trace').par.Sundiry

Default:

0.5

Range:

-1 to 1

Sun Direction (Sundirz) Float op('path_trace').par.Sundirz

Default:

0.4

Range:

-1 to 1

Sun Intensity (Sunintensity) Float op('path_trace').par.Sunintensity

Default:

1

Range:

0 to 20

Sky Intensity (Skyintensity) Float op('path_trace').par.Skyintensity

Default:

1

Range:

0 to 4

Environment As Light (Envaslight) Toggle op('path_trace').par.Envaslight

Default:

On

Options:

Off, On

Importance Sample (Envimportance) Toggle op('path_trace').par.Envimportance

Default:

On

Options:

Off, On