Object Pose Recognition Using Triangulation-Weighted RANSAC

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Solution Overview

Problem

Conventional object pose recognition methods using RANSAC algorithms face inefficiencies and low success rates when the ratio of wrong matching point pairs exceeds 50%, especially when the error rate reaches 80%, leading to unreasonably long calculation times or failure to calculate a correct transformation matrix.

Innovation Solution

A method incorporating triangulation and a probability weighted RANSAC algorithm to analyze matching error probabilities, weighting feature point pairs, and selecting points with higher accuracy through a probabilistic approach to improve the RANSAC method's efficiency and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional RANSAC algorithm is used to select correct feature point pairs, then the method is simple to implement, but when the ratio of wrong matching point pairs exceeds 50%, the calculation time becomes unreasonably long or correct transformation matrix cannot be calculated

Engineering Contradiction:
Improveease of implementationVSAvoidcalculation efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent performs preliminary triangulation on all matched feature point pairs before applying RANSAC. By constructing triangles from corresponding feature points in template and actual images and calculating their intersection points, the method pre-identifies likely correct matching pairs. This preliminary action filters out many wrong matches before RANSAC begins, allowing the algorithm to converge much faster even when wrong match ratio exceeds 50%.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces triangulation and intersection point calculation as an intermediary step between feature point matching and RANSAC transformation matrix calculation. The intersection points of triangles formed by corresponding feature points serve as a mediator that provides geometric constraints to identify correct matches. This intermediary mechanism bridges the gap between raw feature matches and reliable pose estimation, enabling RANSAC to work efficiently even with high error rates.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If traditional RANSAC algorithm is used to calculate transformation matrix, then the algorithm can handle mismatching, but when wrong matching ratio is high, the success rate of calculating correct transformation matrix decreases

Engineering Contradiction:
Improverobustness to mismatchingVSAvoidtransformation matrix accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary triangulation and intersection point calculation to pre-identify correct feature point pairs before RANSAC. By using geometric constraints from triangle intersections, the method pre-filters matching pairs to ensure higher quality input for RANSAC. This preliminary action maintains robustness against mismatching while significantly improving the likelihood of obtaining an accurate transformation matrix even when wrong match ratio exceeds 50%.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces the purely statistical random sampling mechanism of traditional RANSAC with a geometric constraint-based selection method. Instead of relying solely on random sampling and iterative validation, the method uses triangulation geometry and intersection point analysis to deterministically identify correct feature point pairs. This substitution of geometric reasoning for random mechanical sampling improves both success rate and precision of transformation matrix calculation.

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

Data Source

PatentUS12573085B2Object pose recognition method based on triangulation and probability weighted RANSAC algorithm
Publication Date: 2026.03.10 ZHEJIANG UNIV
  • US12573085B2 patent drawing
  • US12573085B2 patent drawing
  • US12573085B2 patent drawing

AI summary

The present invention discloses an object pose recognition method based on triangulation and a probability weighted RANSAC algorithm. First, an actual image and a template image are photographed as input, foreground parts of the input images are extracted, feature points are extracted by means of an SIFT algorithm, the feature points of the actual image and the template image are matched, and each pair of feature points is numbered. Then, the actual image is triangulated, serial numbers of the feature points at vertexes of each triangle are recorded, and the feature points are reconnected into triangles in the model image according to the serial numbers of the points. Next, each feature point is assigned with a certain probability according to intersections of line segments around the feature point. Finally, when a RANSAC algorithm is used, four feature points are probabilistically selected to calculate a spatial transformation matrix, an error generated by the spatial transformation matrix is calculated, and when the error satisfies a set condition, the matrix is the calculated spatial transformation matrix. The present invention can calculate an accurate object pose, achieve higher efficiency, and meet the requirements of practical application.