Bayesian Network Classifier for 3D Object Detection in 2D Images

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Solution Overview

Problem

Existing object detection techniques in 2D images struggle with variations in object appearance, geometry, and orientation, leading to inefficiencies in detection and recognition, particularly when objects are not in a fully frontal posture, and require significant computational resources and human intervention for feature selection.

Innovation Solution

A system and method using a cascade of view-based detectors with Bayesian networks to detect 3D objects in 2D images, where each detector computes a wavelet transform to generate localized transform coefficients, and a cascade of Bayesian network-based classifiers evaluates these coefficients in ascending order of complexity to determine object pose and orientation, automatically learning features from labeled data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If statistical modeling techniques are used to represent object variability, then the system can accommodate variations in appearance, but the ability to represent small areas in a rich and detailed way is compromised

Engineering Contradiction:
Improveaccommodation of appearance variationsVSAvoidrepresentation detail of small areas
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent divides the object detection problem into multiple component parts by representing objects as collections of geometric primitives (ellipses, rectangles, triangles) and visual features (color, texture, shape). Each primitive and feature is modeled separately with its own statistical parameters, allowing detailed representation of small areas while maintaining overall adaptability to variations in appearance, pose, and lighting conditions

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If decomposition into smaller regions is used to represent appearance, then small areas can be represented in detail, but the computational complexity increases

Engineering Contradiction:
Improverepresentation detail of small areasVSAvoidcomputational complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the object into geometric primitives and visual features that can be modeled independently. This segmentation allows detailed representation of small regions while reducing computational complexity through the use of compact statistical models (mean, covariance) for each primitive and feature, avoiding the need to process entire high-resolution images

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the complex problem of representing detailed small areas into a parameter-based representation system. Each geometric primitive is defined by a small set of parameters (position, size, orientation, shape), and each visual feature by statistical parameters (mean, covariance). This parameterization dramatically reduces computational complexity while maintaining detailed representation capability

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If exhaustive search over all possible object positions and sizes is performed, then detection accuracy is improved, but computational time increases significantly

Engineering Contradiction:
Improvedetection accuracyVSAvoidcomputational time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by pre-computing and storing statistical models (mean, covariance) for geometric primitives and visual features from training data. During detection, these pre-computed models are used to quickly evaluate candidate regions without requiring exhaustive analysis of all possible positions and sizes, thereby reducing computational time while maintaining detection accuracy

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies partial action by evaluating only the most promising candidate regions identified through initial filtering, rather than performing exhaustive search over all possible positions and sizes. The system uses statistical models to quickly assess likelihood of object presence in candidate regions, applying detailed analysis only where needed, thus reducing overall computational time while maintaining high detection accuracy

Inventive Principle:
Principle #16Partial or excessive action

4Adaptability or versatility

If handpicked features are used to allow geometric flexibility, then small variations can be accommodated, but the power of the technique is limited

Engineering Contradiction:
Improveaccommodation of small variationsVSAvoidpower of the technique
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal framework that can detect various object types (faces, cars, airplanes) using the same geometric primitives and visual features. The system is not limited to handpicked features for specific objects but instead uses a general-purpose set of primitives (ellipses, rectangles, triangles) and features (color, texture, shape) that can represent geometric flexibility and accommodate small variations across multiple object classes, significantly increasing the power and versatility of the technique

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

Data Source

PatentUS9213885B1Object recognizer and detector for two-dimensional images using Bayesian network based classifier
Publication Date: 2015.12.15 GOOGLE LLC
  • US9213885B1 patent drawing
  • US9213885B1 patent drawing
  • US9213885B1 patent drawing

AI summary

System and method for determining a classifier to discriminate between two classes—object or non-object. The classifier may be used by an object detection program to detect presence of a 3D object in a 2D image. The overall classifier is constructed of a sequence of classifiers, where each such classifier is based on a ratio of two graphical probability models. A discreet-valued variable representation at each node in a Bayesian network by a two-stage process of tree-structured vector quantization is discussed. The overall classifier may be part of an object detector program that is trained to automatically detect different types of 3D objects. Computationally efficient statistical methods to evaluate overall classifiers are disclosed. The Bayesian network-based classifier may also be used to determine if two observations belong to the same category.