Path Tracer

Summary

Path Tracer is a GPU-accelerated physically-based renderer that uses the Ray POP operator internally to compute ray-geometry intersections. This operator implements Monte Carlo path tracing with the Disney principled BRDF material model, enabling realistic lighting and material simulation. The path tracer supports progressive rendering for clean convergence, depth of field effects through aperture simulation, and HDR tone mapping for proper exposure control.

The operator provides comprehensive material controls following the Disney BRDF standard, including base color, metallic/roughness workflows, specular reflections with anisotropic highlights, subsurface scattering, sheen for fabric-like materials, clearcoat layering, and transmission for glass. Lighting is handled through environment maps (HDR images) and direct light sources (point, spot, and area lights) with full transform controls. You can override existing materials on input geometry or respect per-primitive material attributes.

Path Tracer renders images to the Render TOP specified in the parameter with optional tone mapping and exposure adjustment. Progressive rendering accumulates samples over time for noise reduction, while temporal smoothing provides frame-to-frame coherence for animations. The renderer supports adjustable ray counts per pixel, bounce depth limits, and camera effects including depth of field with focal length and aperture controls. This makes Path Tracer ideal for high-quality offline rendering, lookdev workflows, physically accurate lighting studies, or real-time progressive preview of complex scenes.

Parameters

Page: Path Tracing

Enable Path Tracing Enable – Master toggle for path tracing rendering.
Reset Reset – Pulse to reset progressive accumulation and restart rendering.
Lock Input Lockinput – Freeze input geometry to prevent updates during progressive rendering.
Progressive Rendering Progressiverendering – Accumulate samples over time for noise-free convergence.
Temporal Smoothing Temporalsmoothing – Frame blending amount for temporal coherence. Available when progressive rendering is off.
Render TOP Rendertop – Reference to Render TOP providing camera and viewport settings that the path tracer will render to.
Rays per Pixel Raysperpixel – Number of rays cast per pixel per frame.
Max Bounces Maxbounces – Maximum ray bounce depth for global illumination.
Opaque Geometry Opaque – Treat all geometry as opaque.
Aperture Aperture – Camera aperture size for depth of field.
Focal Length Focallength – Distance from camera where objects are in sharp focus.
Enable Tone Map Enabletonemap – Apply tone mapping to convert HDR output to display range.
Exposure Exposure – Exposure multiplier for tone mapping.

Page: Material

Override if Material Exists Overrideifexists – Apply material parameters even when geometry has existing material attributes.
Base Color Basecolor – – Diffuse albedo color.
Base Color Basecolorr
Base Color Basecolorg
Base Color Basecolorb
Base Color Basecolora
Metallic Metallic – Metallic appearance.
Roughness Roughness – Surface roughness.
Specular Specular – Specular reflection strength for dielectrics.
Specular Tint Speculartint – Tint specular reflection with base color.
Anisotropic Anisotropic – Anisotropic highlight stretching.
Anisotropic Rotation Anisotropicrot – Rotation angle for anisotropic highlights.
Subsurface Subsurface – Subsurface scattering amount for translucent materials like skin or wax.
Sheen Sheen – Soft velvet-like reflection for fabrics and cloth.
Sheen Tint Sheentint – Tint sheen with base color.
Clearcoat Clearcoat – Secondary specular layer for car paint or lacquered surfaces.
Clearcoat Gloss Clearcoatgloss – Glossiness of clearcoat layer.
IOR Ior – Index of refraction for dielectrics.
Transmission Transmission – Light transmission through surface for glass and transparent materials.
Emission Emission – – Emissive color for self-illuminating surfaces.
Emission Emissionr
Emission Emissiong
Emission Emissionb
Emission Emissiona

Page: Lights

Enable Environment Light Enableenv – Enable image-based lighting from environment map.
Render Environment Renderenv – Show environment map in background when rays miss geometry.
Environment Map Intensity Envmapintensity – Multiplier for environment light contribution.
Environment Map Environmentmap – HDR environment texture.
Enable Direct Light Enabledirectlight – Enable direct lighting.
Render Lights Renderlights – Show light geometry in render.
Lights Lights – Sequence of light sources with individual properties.
Light Type Lights0type – – Type of light source.
Point Light point
Spot Light spot
Area Light area
Light Color Lights0color – – Light color.
Light Color Lights0colorr
Light Color Lights0colorg
Light Color Lights0colorb
Dimmer Lights0dimmer – Light intensity multiplier.
Transform Order Lights0xord – Order of transformation operations.
Rotate Order Lights0rord – Rotation axis order.
Translate Lights0t – – Light position in world space.
Translate Lights0tx
Translate Lights0ty
Translate Lights0tz
Rotate Lights0r – – Light rotation in degrees for spot and area lights.
Rotate Lights0rx
Rotate Lights0ry
Rotate Lights0rz
Scale Lights0s – – Light scale for area lights only.
Scale Lights0sx
Scale Lights0sy
Scale Lights0sz
Pivot Lights0p – – Pivot point for light transformations.
Pivot Lights0px
Pivot Lights0py
Pivot Lights0pz
Uniform Scale Lights0scale – Uniform scale multiplier for all axes for area lights.
Bi-Directional Lights0bidirectional – Area and spot lights emit from both sides of surface.
Cone Angle Lights0coneangle – Spotlight cone angle in degrees.
Cone Delta Lights0conedelta – Spotlight falloff width at cone edge.
Cone Rolloff Lights0coneroll – Spotlight intensity falloff curve.

Page: Common

Free Extra GPU Memory Freeextragpumem – Free memory that has accumulated when output memory has grown and shrunk.

Inputs

Input 0 POP – POPX_in1