Machine Learning Denoising Monte Carlo Rendered Images

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Solution Overview

Problem

Monte Carlo rendering systems produce noisy images due to the high variance of the MC estimator, requiring many samples for reliable estimation, leading to lengthy render times and challenges in denoising distributed effects while preserving scene detail.

Innovation Solution

A machine learning model is used to denoise Monte Carlo rendered images by leveraging colors and features from the rendering system, either by directly filtering the images or adaptively placing samples, trained with ground truth images to remove noise and improve filtering processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Monte Carlo rendering uses more samples to reduce noise, then image quality improves, but render time increases significantly

Engineering Contradiction:
Improveimage qualityVSAvoidrender time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary denoising filters to the Monte Carlo rendered image to remove noise before final processing. By pre-filtering the noisy image using techniques such as bilateral filtering or non-local means filtering, the system achieves acceptable image quality without requiring a large number of samples, thus reducing render time while maintaining measurement precision

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediate denoising step between the Monte Carlo sampling process and the final image output. This intermediary filtering process acts as a mediator that separates the noise removal function from the rendering sampling, allowing the system to use fewer samples while achieving low noise levels through the intermediate filtering stage

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If Monte Carlo rendering uses fewer samples to reduce render time, then productivity improves, but image quality deteriorates due to high noise

Engineering Contradiction:
Improverender speedVSAvoidimage quality
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful noise in low-sample Monte Carlo images into a benefit by applying specialized denoising filters that exploit the statistical properties of Monte Carlo noise. By using filters designed specifically for MC rendering that incorporate scene geometry and lighting information, the system transforms the noisy low-sample images into high-quality results, enabling fast rendering without quality loss

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If feature-based filters are used to denoise distributed effects, then image quality improves, but device complexity increases due to multiple filter parameters

Engineering Contradiction:
Improvedenoising qualityVSAvoidfilter parameter complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent dynamically adjusts filter parameters based on local image characteristics and scene features. By changing filter parameters such as kernel size, sigma values, and weighting factors adaptively according to the local variance, edge detection, and scene depth information, the system achieves high denoising quality for distributed effects while maintaining manageable complexity through automated parameter adjustment rather than manual configuration

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS10832091B2Machine learning to process Monte Carlo rendered images
Publication Date: 2020.11.10 RGT UNIV OF CALIFORNIA
  • US10832091B2 patent drawing
  • US10832091B2 patent drawing
  • US10832091B2 patent drawing

AI summary

A method of rendering an image includes Monte Carlo rendering a scene to produce a noisy image. The noisy image is processed to render an output image. The processing applies a machine learning model that utilizes colors and/or features from the rendering system for denoising the noisy image and/or to for adaptively placing samples during rendering.