Mike Gold

Epic Enhances Path Tracing with Stable NFOR Denoiser

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Posted on X by Dylan Browne Epic added a new denoiser for Path Tracing this week, NFOR, specifically designed for sequence rendering, it appears incredibly stable compared to the default denoiser, with more normal looking noise vs the insane warbling with the default. #UE5 #UnrealEngine #GameDev #Cinematic

Unreal Engine's NFOR Denoiser for Path Tracing

Overview

Epic Games has introduced a new denoiser called NFOR (spatio-temporal denoiser) specifically for path tracing in Unreal Engine, designed to improve sequence rendering. This denoiser is more stable and produces less aggressive noise compared to the default denoiser, making it particularly suitable for cinematic rendering. It leverages spatio-temporal data to enhance image quality over time.

Technical Analysis

NFOR is an experimental feature introduced by Epic Games as part of their ongoing improvements to Unreal Engine's rendering capabilities. Unlike traditional denoisers, NFOR uses a spatio-temporal approach, which means it combines spatial and temporal information to reduce noise more effectively. This method ensures that the resulting images are smoother and less visually distracting compared to the default denoiser, which often produces "insane warbling" as described in the post [1].

The implementation of NFOR is particularly suited for sequence rendering, where maintaining consistency across frames is critical. According to Epic's documentation [2], NFOR operates by analyzing both the current frame and previous frames to predict and remove noise patterns. This temporal coherence helps in achieving more stable and visually appealing results, especially for cinematic content.

Additionally, the introduction of NFOR aligns with Unreal Engine's broader focus on improving path tracing, a rendering technique that simulates light interactions more accurately than traditional methods like Lumen. While Lumen is optimized for real-time performance, path tracing offers higher fidelity but requires more computational resources. The integration of NFOR into Unreal Engine 5.5 further enhances the appeal of path tracing for cinematic projects [3].

Implementation Details

NFOR is implemented as an experimental feature in Unreal Engine's rendering pipeline. Key technical details include:

  • Spatio-temporal denoising: Combines spatial and temporal data to reduce noise effectively.
  • Temporal coherence: Analyzes multiple frames to predict and remove noise patterns.
  • Integration with path tracing: Enhances the visual quality of path-traced renders for sequences.

The denoiser is available as part of Unreal Engine's public roadmap [4], indicating its status as an ongoing development effort. Developers can access documentation and forums related to NFOR for implementation guidance [2, 5].

NFOR builds upon Unreal Engine's existing rendering technologies, including:

  • Lumen: A real-time global illumination system optimized for performance, but less suited for cinematic rendering compared to path tracing. [3]
  • Path Tracer: A high-fidelity rendering method that simulates light interactions, offering superior visual quality but requiring significant computational resources. [4]

The introduction of NFOR also complements Unreal Engine's growing emphasis on cinematic-grade rendering tools, such as the recently updated Sequencer and Scene Management System.

Key Takeaways

  • NFOR is experimental: It is currently under development and part of Unreal Engine's public roadmap [4].
  • Stability and noise reduction: NFOR produces more stable and visually appealing results compared to the default denoiser, particularly for sequence rendering [1, 2].
  • Spatio-temporal approach: Unlike traditional denoisers, NFOR leverages both spatial and temporal data to enhance image quality over time [2, 5].

Further Research

Further Reading

  • Epic introduces NFOR for path tracing - Learn about Epic's introduction of NFOR for enhancing path tracing in Unreal Engine: LinkedIn Post
  • NFOR Denoiser Documentation - Official documentation on the NFOR spatio-temporal denoiser in Unreal Engine: Epic Developer Community
  • Lumen vs Path Tracer Comparison - Explore the differences between Lumen and Path Tracer in Unreal Engine 5.5: Rendering Insights
  • NFOR on Unreal Engine Roadmap - View NFOR's status as an experimental feature in the public roadmap of Unreal Engine: ProductBoard
  • Temporal Denoiser Discussion - Read forum discussions about using a temporal denoiser for path tracer movie renders: Unreal Engine Forums
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