Self-Occlusion Masks for Multi-Camera Depth Estimation

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Solution Overview

Problem

Conventional self-supervised depth and ego-motion models are limited in their application to multi-camera settings due to self-occlusions caused by the ego vehicle's body, which prevents optimal camera placement and results in unsuitable data for learning, especially when cameras are placed on streamlined roof racks for aesthetics or aerodynamics.

Innovation Solution

A method that involves generating a hard-coded binary mask by manually segmenting self-occluded areas in images captured by a multi-camera rig, which is then used to mask the photometric loss during training, avoiding gradient back-propagation in self-occluded areas and enabling accurate depth and ego-motion estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If cameras are placed on streamlined roof rack for aesthetics or aerodynamics, then aerodynamic performance and esthetics are improved, but self-occlusion increases making depth estimation unreliable

Engineering Contradiction:
Improveaerodynamic performanceVSAvoiddepth estimation reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent segments the loss function computation by introducing self-occlusion masks that divide the image into reliable and unreliable regions. The photometric loss is computed separately for non-occluded and occluded areas, allowing the model to learn from valid regions while excluding corrupted regions from gradient updates.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different quality standards to different regions of the image. Non-occluded regions are used for standard photometric loss computation, while occluded regions are identified and excluded using self-occlusion masks. This local differentiation ensures that only high-quality, reliable image regions contribute to the training signal.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If conventional self-supervised methods are used, then forward-facing camera depth estimation is improved, but side-facing and rear-facing cameras with self-occlusions cannot be effectively utilized

Engineering Contradiction:
Improvedepth estimation precisionVSAvoidcamera placement adaptability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal self-occlusion masking framework that works across all camera orientations (forward-facing, side-facing, rear-facing). The same photometric loss function with self-occlusion masking can be applied to any camera in the multi-camera rig, making the system adaptable to diverse camera placements and configurations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the parameters of the loss function by introducing self-occlusion masks that modulate the photometric loss. This parameter modification allows the system to adapt to different camera viewpoints and occlusion patterns, enabling effective training for side and rear cameras that were previously unusable.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If self-occluded areas are included in training, then more data is available for learning, but gradient back-propagation becomes unsuitable leading to poor learning results

Engineering Contradiction:
Improvedata utilization efficiencyVSAvoidlearning signal quality
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent extracts and removes self-occluded regions from the training process by generating binary masks that identify these problematic areas. The photometric loss is then computed only on non-occluded regions, effectively taking out the harmful data portions while retaining useful data for training.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The self-occlusion mask acts as an intermediary between the raw image data and the loss computation. This intermediate binary mask selectively gates the photometric loss signal, allowing gradients to flow only from reliable, non-occluded regions while blocking corrupted signals from occluded areas.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS11875521B2Self-occlusion masks to improve self-supervised monocular depth estimation in multi-camera settings
Publication Date: 2024.01.16 TOYOTA JIDOSHA KK
  • US11875521B2 patent drawing
  • US11875521B2 patent drawing
  • US11875521B2 patent drawing

AI summary

A method for self-supervised depth and ego-motion estimation is described. The method includes determining a multi-camera photometric loss associated with a multi-camera rig of an ego vehicle. The method also includes generating a self-occlusion mask by manually segmenting self-occluded areas of images captured by the multi-camera rig of the ego vehicle. The method further includes multiplying the multi-camera photometric loss with the self-occlusion mask to form a self-occlusion masked photometric loss. The method also includes training a depth estimation model and an ego-motion estimation model according to the self-occlusion masked photometric loss. The method further includes predicting a 360° point cloud of a scene surrounding the ego vehicle according to the depth estimation model and the ego-motion estimation model.