Path Tracer¶
UE's reference path tracer for cinematic-quality offline renders. Not a real-time mode. Targets Movie Render Queue and high-end stills.
Enable¶
r.PathTracing 1 in the viewport (set as Real-Time Path Tracing in View Mode) or as a setting per shot in Movie Render Queue.
Requires a DXR-capable GPU and r.RayTracing 1.
Capabilities¶
| Feature | Status |
|---|---|
| Multi-bounce diffuse / specular | ★ |
| Refraction / caustics | ★ |
| Volumetric scattering | ★ |
| Subsurface scattering | ★ |
| Hair / Strand rendering | ★ |
| Path-traced GI denoiser | OIDN / OptiX |
| Motion blur | ★ (accurate, ground-truth) |
| DoF | ★ |
| Material override (white furnace) | ★ |
Workflow with Movie Render Queue¶
- Add a Movie Render Queue job
- Render Settings → + Path Tracer
- Set Reference Motion Blur and Sample Count (256–1024 for production)
- Enable OIDN Denoiser in the Anti-Aliasing settings
- Use Console Variables preset to push quality CVars
Quality CVars¶
| CVar | Effect |
|---|---|
r.PathTracing.MaxBounces 16 |
Bounce limit |
r.PathTracing.SamplesPerPixel 1024 |
Convergence budget |
r.PathTracing.UseDLSSDenoiser 1 |
DLSS Ray Reconstruction denoise |
r.PathTracing.AdaptiveSampling 1 |
Sample where noise lives |
r.PathTracing.MaxPathIntensity 50 |
Firefly clamp |
When to use¶
- Final-frame cinematics, key art, marketing renders.
- Reference baseline to evaluate Lumen quality against.
- Light-baking workflows when Lightmass is too noisy.
When not to use¶
- Any real-time application.
- Animated characters with rapidly-changing topology (cache misses dominate).