Fully Convolutional Network for Visual Correspondence

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Solution Overview

Problem

Existing visual correspondence methods, particularly those using convolutional neural networks (CNNs), are inefficient as they rely on surrogate objective functions and patch-based similarity measures, leading to suboptimal feature extraction and high computational costs for tasks like stereo disparity and structure from motion, due to the need for O(n^2) feed-forward passes and lack of optimization for metric spaces.

Innovation Solution

A fully convolutional neural network (FCNN) with a correspondence contrastive loss and active hard negative mining is proposed, enabling efficient feature extraction and learning of metric spaces for visual correspondences, along with a convolutional spatial transformer for patch normalization, allowing for faster training and testing with reduced computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If patch-based similarity methods are used, then image patch similarity can be measured, but computational complexity increases to O(n^2) feed-forward passes

Engineering Contradiction:
Improvepatch similarity measurementVSAvoidcomputational efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the image into dense feature points and uses a fully convolutional network to extract features at each point independently, avoiding the need to compare all pairs of patches. This segmentation approach reduces computational complexity from O(n^2) to O(n) while maintaining measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical patch-based comparison system with a neural network-based feature extraction system. By using convolutional neural networks to learn metric spaces directly, the system eliminates the need for exhaustive patch pairing and similarity computation, achieving both precision and efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If intermediate convolution features are used, then features can be extracted, but they are not optimized for visual correspondence tasks

Engineering Contradiction:
Improvefeature extraction speedVSAvoidvisual correspondence accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs dynamic feature extraction by training the convolutional network to adaptively learn metric spaces through contrastive loss functions. The network dynamically adjusts feature representations based on correspondence relationships, ensuring both efficient extraction and high accuracy for visual correspondence tasks.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter space by transforming intermediate convolution features into optimized metric space features through contrastive loss training. This parameter transformation ensures that features are both efficiently extractable and precisely suitable for visual correspondence, resolving the contradiction between extraction speed and accuracy.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If dense feature extraction is performed, then correspondence density increases, but computational cost increases

Engineering Contradiction:
Improvecorrespondence densityVSAvoidcomputational energy consumption
Core Design Contradiction:
Quantity of substanceVSUse of energy by stationary object

Solution Approach 1:

The patent creates a universal fully convolutional network that can extract dense features efficiently for multiple correspondence tasks simultaneously. The network's multi-functionality allows it to handle both geometric and semantic correspondences with a single model, increasing correspondence density without proportionally increasing computational energy consumption.

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

Data Source

PatentUS10115032B2Universal correspondence network
Publication Date: 2018.10.30 NEC CORP
  • US10115032B2 patent drawing
  • US10115032B2 patent drawing
  • US10115032B2 patent drawing

AI summary

A computer-implemented method for training a convolutional neural network (CNN) is presented. The method includes extracting coordinates of corresponding points in the first and second locations, identifying positive points in the first and second locations, identifying negative points in the first and second locations, training features that correspond to positive points of the first and second locations to move closer to each other, and training features that correspond to negative points in the first and second locations to move away from each other.