Humanoid Skeleton Extraction from Depth Maps

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Solution Overview

Problem

Existing methods for processing depth maps struggle to efficiently capture and extract high-level information, particularly in tracking moving humanoid forms, which hinders the development of applications that rely on 3D mapping technology.

Innovation Solution

A method and system that process temporal sequences of depth maps to locate and estimate the dimensions of a humanoid form, reconstructing a 3D skeleton model of the body, allowing for accurate tracking of movements without the need for markers or sensors, by identifying key features like arms, shoulders, and head, and registering with 2D images for face recognition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing methods process depth maps to identify objects, then object segmentation is achieved, but efficiency in capturing and extracting high-level information deteriorates

Engineering Contradiction:
Improveobject identification accuracyVSAvoidinformation extraction efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the depth map processing into distinct stages: initial object segmentation, skeleton extraction, and hierarchical feature analysis. By dividing the complex processing task into manageable segments, the system achieves both accurate object identification and efficient information extraction, resolving the contradiction between precision and productivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts skeletons as simplified representations from full depth maps, removing unnecessary detail while preserving essential structural information. This extraction process maintains measurement precision for tracking while significantly improving processing efficiency by working with reduced data complexity

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If depth maps are processed to track humanoid movements, then movement tracking capability is improved, but device complexity increases

Engineering Contradiction:
Improvemovement tracking reliabilityVSAvoidprocessing system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates simplified skeleton copies that represent the essential structure and movement of humanoids without requiring full-depth-map processing. These skeleton models serve as lightweight representations that maintain tracking reliability while reducing the computational complexity of the processing system

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent transitions from processing full 3D depth map data to extracting 1D skeletal representations and 2D joint positions. This dimensional reduction allows reliable movement tracking while significantly simplifying the processing requirements, resolving the contradiction between reliability and device complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If skeletons are extracted from depth maps, then tracking accuracy is improved, but processing time increases

Engineering Contradiction:
Improvetracking accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary skeleton extraction and dimension estimation on the first frame before processing subsequent frames. This preliminary action establishes accurate tracking references that can be maintained across multiple frames, improving tracking accuracy while reducing the processing time required for each individual frame

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous tracking by updating skeleton positions and dimensions across temporal sequences of depth maps. Once skeletons are extracted, the system continuously tracks their movement with minimal re-processing, preserving tracking accuracy while minimizing additional processing time through efficient frame-to-frame updates

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentUS9235753B2Extraction of skeletons from 3D maps
Publication Date: 2016.01.12 APPLE INC
  • US9235753B2 patent drawing
  • US9235753B2 patent drawing
  • US9235753B2 patent drawing

AI summary

A method for processing data includes receiving a temporal sequence of depth maps of a scene containing a humanoid form having a head. The depth maps include a matrix of pixels having respective pixel depth values. A digital processor processes at least one of the depth maps so as to find a location of the head and estimates dimensions of the humanoid form based on the location. The processor tracks movements of the humanoid form over the sequence using the estimated dimensions.