Monocular Depth Prediction in Low Light via Synthetic Training

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Solution Overview

Problem

Systems using monocular cameras face difficulties in generating accurate depth maps in low-light conditions, particularly at nighttime, and combining information from monocular cameras with other sensors increases complexity.

Innovation Solution

A two-stage training approach for a prediction system that uses synthetic images to simulate daytime representations of low-light environments, employing pose and flow losses to improve semantic consistency, and then applies these models to real low-light images using an adversarial network to generate clearer depth maps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a monocular camera is used to predict depth without relying on LIDAR or stereo cameras, then device complexity is reduced, but measurement precision of depth map deteriorates

Engineering Contradiction:
Improvesensor system complexityVSAvoiddepth map accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system performs preliminary training using synthetic images with ground truth depth maps to pre-train the neural network. This preliminary action allows the model to learn depth prediction patterns before being deployed with real monocular images, thereby improving measurement precision while maintaining device simplicity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system creates synthetic copies of real-world scenes with known depth information to train the model. These synthetic images serve as proxies for real depth data, allowing the system to learn from simulated environments and apply the learned patterns to real monocular images, thus improving depth prediction accuracy without additional sensors.

Inventive Principle:
Principle #26Copying

2Reliability

If the system is trained for low-light conditions using real data, then reliability in low-light environments is improved, but loss of information increases due to noise and poor visibility

Engineering Contradiction:
Improvelow-light operation reliabilityVSAvoidimage quality information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The system uses synthetic images that copy the appearance and lighting conditions of low-light environments but without the noise and information loss of real low-light photographs. These synthetic copies provide clean training data that teaches the model how to handle low-light scenarios without being corrupted by actual low-light degradation.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system changes the lighting parameters in synthetic images to simulate various low-light conditions (moonlight, streetlights, twilight) while maintaining perfect image quality. By adjusting illumination parameters in the synthetic data rather than using degraded real low-light images, the model learns robust low-light prediction without information loss.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If pose and flow losses are computed to account for object motion between frames, then measurement precision of depth map is improved, but loss of time increases due to additional computations

Engineering Contradiction:
Improvedepth map accuracyVSAvoidtraining and processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system computes pose and flow losses during the training phase rather than during real-time operation. By performing these additional computations in advance during training, the model internalizes the motion compensation knowledge, allowing for faster real-time depth prediction without sacrificing accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses pose and flow losses as feedback signals during training to guide the optimization of depth prediction. These loss functions provide directional guidance to the gradient descent algorithm, improving convergence efficiency and reducing overall training time while maintaining high measurement precision.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS12014507B2Systems and methods for training a prediction system
Publication Date: 2024.06.18 TOYOTA JIDOSHA KK
  • US12014507B2 patent drawing
  • US12014507B2 patent drawing
  • US12014507B2 patent drawing

AI summary

System, methods, and other embodiments described herein relate to training a prediction system for improving depth perception in low-light. In one embodiment, a method includes computing, in a first training stage, losses associated with predicting a depth map for a synthetic image of a low-light scene, wherein the losses include a pose loss, a flow loss, and a supervised loss. The method also includes adjusting, according to the losses, a style model and a depth model. The method also includes training, in a second training stage, the depth model using a synthetic representation of a low-light image. The method also includes providing the depth model.