End-to-End Neural Network for Pose-Invariant Face Alignment

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Solution Overview

Problem

Face alignment technologies using cascades of Convolutional Neural Networks (CNNs) face issues such as lack of end-to-end training, reliance on hand-crafted feature extraction, and slow training speed due to sequential training of shallow frameworks, which limits their ability to extract deeper features and handle facial variations like pose and expression effectively.

Innovation Solution

A computing system employing a single neural network with end-to-end training and visualization layers that generate feature maps for head pose and face shape data, allowing joint optimization and faster convergence, thereby overcoming the limitations of traditional cascades of CNNs by integrating differentiable visualization layers for joint parameter estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If cascades of CNNs are used for face alignment, then the system can process facial images, but the training speed is slow due to sequential training of multiple shallow frameworks

Engineering Contradiction:
Improvetraining speedVSAvoidsystem structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges multiple separate CNN frameworks into a single unified end-to-end trainable network. This consolidation allows joint optimization of all components simultaneously, eliminating the sequential training bottleneck and significantly improving training speed while maintaining the functional capabilities of the original cascade structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces dynamic feature extraction capabilities within the unified network, allowing the system to adaptively adjust feature representation at different stages of processing. This enables the network to effectively handle various facial variations including pose and expression changes, improving both training efficiency and alignment accuracy.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If hand-crafted feature extraction is used between CNNs, then the system can process features, but it does not take into account various facial factors such as pose and expression

Engineering Contradiction:
Improvehandling of facial factorsVSAvoidfeature extraction method
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent replaces hand-crafted feature extraction methods with automated learned feature extraction through the unified neural network. This substitution enables the system to automatically adapt to various facial factors like pose and expression by learning appropriate feature representations from data, rather than relying on fixed hand-crafted features that cannot capture these variations.

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

Solution Approach 2:

The patent employs parameter changes by allowing the network to dynamically adjust feature extraction parameters based on the input image characteristics. This enables adaptive feature representation that responds to different facial conditions, improving versatility while simplifying the overall system design through end-to-end learning.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If shallow CNN frameworks are used, then the system structure is simpler, but the frameworks are unable to extract deeper features by building upon the extracted features of early-stage CNNs

Engineering Contradiction:
Improvefeature extraction depthVSAvoidnetwork framework
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the feature extraction process into multiple hierarchical stages within a unified network architecture. Each stage builds upon the features extracted by previous stages, enabling progressive deep feature extraction. This segmentation allows the network to capture both fine-grained and coarse-grained facial features while maintaining end-to-end trainability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a nested architecture where deeper feature extraction layers are embedded within the unified network structure. Each layer processes and refines features from previous layers, creating a nested hierarchy that enables deep feature extraction while maintaining system coherence and joint optimizability through end-to-end training.

Inventive Principle:
Principle #7Nested doll (Nesting)

Data Source

PatentUS10380413B2System and method for pose-invariant face alignment
Publication Date: 2019.08.13 ROBERT BOSCH GMBH
  • US10380413B2 patent drawing
  • US10380413B2 patent drawing
  • US10380413B2 patent drawing

AI summary

A computing system includes a processing system with at least one processing unit. The processing system is configured to execute a face alignment method upon receiving image data with a facial image. The processing system is configured to apply a neural network to the facial image. The neural network is configured to provide a final estimate of parameter data for the facial image based on the image data and an initial estimate of the parameter data. The neural network includes at least one visualization layer, which is configured to generate a feature map based on a current estimate of the parameter data. The parameter data includes head pose data and face shape data.