Key-Point Association Using Direction Maps for Faster Grouping

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Solution Overview

Problem

Existing key-point association techniques, such as those using Part Affinity Fields (PAF), often include regions apart from the key-points, leading to slow convergence during training and inefficiencies in key-point grouping.

Innovation Solution

A key-point associating apparatus and method that generates spatial feature maps with separate direction regions for each key-point pair, avoiding regions between key-points and enabling efficient grouping of key-points belonging to the same person.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If PAF includes regions apart from key-points (such as middle point regions), then the feature map can represent directional information between key-points, but training convergence becomes slow

Engineering Contradiction:
Improvedirectional information representationVSAvoidtraining convergence time
Core Design Contradiction:
Loss of informationVSLoss of time

Solution Approach 1:

The patent extracts only the necessary directional information from key-point regions and removes redundant middle point regions from the feature map. By generating direction maps that contain only directional vectors at key-point locations rather than filling entire regions between key-points, the solution eliminates unnecessary computational data while preserving essential directional relationships for key-point association.

Inventive Principle:
Principle #2Taking out (Extraction)

2Loss of information

If PAF fills regions between key-points with directional pixel values, then directional relationships are represented, but computational efficiency decreases

Engineering Contradiction:
Improvedirectional relationship representationVSAvoidkey-point association efficiency
Core Design Contradiction:
Loss of informationVSProductivity

Solution Approach 1:

The patent segments the feature representation into discrete key-point locations rather than continuous regions. Each key-point has an associated direction map containing only the directional vector to its paired key-point, rather than filling the entire spatial region between them. This segmentation reduces the total number of pixels processed while maintaining directional relationship information.

Inventive Principle:
Principle #1Segmentation

3Loss of information

If the feature map includes redundant regions apart from key-points, then directional information is preserved, but key-point grouping accuracy may be compromised

Engineering Contradiction:
Improvedirectional informationVSAvoidkey-point grouping accuracy
Core Design Contradiction:
Loss of informationVSManufacturing precision

Solution Approach 1:

The patent extracts precise directional vectors at key-point locations and removes redundant middle point regions that could introduce noise or ambiguity. By concentrating directional information only at detected key-point positions rather than distributing it across intermediate regions, the solution improves the precision of key-point pairing decisions while maintaining complete directional information for association.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentUS20260051145A1Key-point associating apparatus, key-point associating method, and non-transitory computer-readable storage medium
Publication Date: 2026.02.19 NEC CORP
  • US20260051145A1 patent drawing
  • US20260051145A1 patent drawing
  • US20260051145A1 patent drawing

AI summary

A key-point associating apparatus acquires a target image on which one or more persons are captured, detects key-points from the target image, and generates a spatial feature map for each one of pairs of the body parts. The spatial feature map includes a first direction region for each key-point that represents a first body part of the corresponding pair and the second direction region for each key-points that represents a second body part of the corresponding pair. The first and second direction regions belonging to a same person as each other represent a direction from the key-point of the first direction region to the key-point of the second direction region. The key-point associating apparatus generates a key-point group for each one of the persons captured on the target image.