Real-Time 3D Scene Reconstruction Using Keyframe Selection

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Solution Overview

Problem

Current video coding technologies struggle to efficiently produce 3D models and estimate camera positions for RGB-D sensors, particularly in real-time applications like virtual reality and augmented reality, where accurate and simultaneous localization and mapping are crucial.

Innovation Solution

Implementing a method that uses RGB-D cameras to select keyframes, adjust them based on probability variance values, and fuse color and depth information to provide a virtual representation of the scene, enabling real-time 3D reconstruction and camera pose estimation within a 3D coordinate system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If traditional video coding technologies are used to produce 3D models from RGB-D sensors, then the processing complexity is reduced, but the accuracy of camera pose estimation and 3D reconstruction deteriorates

Engineering Contradiction:
Improveprocessing complexityVSAvoidcamera pose estimation accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the video stream into keyframes and non-keyframes, processing only keyframes for 3D reconstruction. This segmentation allows the system to maintain high accuracy by selectively processing important frames while reducing overall computational complexity through the use of temporal prediction for non-keyframes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by pre-identifying and selecting keyframes based on motion magnitude and other criteria before the actual 3D reconstruction process. This preliminary selection optimizes the reconstruction accuracy by ensuring that only frames with sufficient information content are used as reference points.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If all frames are processed for 3D reconstruction, then the reconstruction quality is improved, but the processing time increases

Engineering Contradiction:
Improvereconstruction qualityVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent divides the video processing into keyframe processing and non-keyframe processing. Keyframes are fully processed for 3D reconstruction, while non-keyframes utilize temporal prediction and motion compensation, significantly reducing processing time while maintaining acceptable reconstruction quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by processing only a subset of frames (keyframes) in full detail for 3D reconstruction, while using simplified processing for non-keyframes. This selective approach achieves acceptable reconstruction quality with reduced processing time compared to processing all frames equally.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If keyframes are selected based on motion magnitude, then the processing efficiency is improved, but the selection complexity increases

Engineering Contradiction:
Improveprocessing efficiencyVSAvoidkeyframe selection complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent uses parameter changes by evaluating multiple criteria (motion magnitude, time intervals, scene changes) to determine keyframe selection. This multi-parameter approach improves processing efficiency by systematically identifying important frames while managing selection complexity through defined thresholds and weights for each parameter.

Inventive Principle:
Principle #35Parameter changes

4Object-affected harmful factors

If depth values are combined using probability variance, then the noise reduction is improved, but the computational complexity increases

Engineering Contradiction:
Improvenoise reductionVSAvoidcomputational complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces simple averaging mechanisms with probability variance-based fusion for combining depth values from multiple keyframes. This substitution improves noise reduction by accounting for the reliability of each depth measurement, while managing computational complexity through efficient variance calculation and thresholding.

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

Data Source

PatentUS10984583B2Reconstructing views of real world 3D scenes
Publication Date: 2021.04.20 APPLE INC
  • US10984583B2 patent drawing
  • US10984583B2 patent drawing
  • US10984583B2 patent drawing

AI summary

Various implementations are disclosed of producing a 3-dimensional model of a scene. Various method, electronic device, or system implementations use RGB-D camera to provide RGB-D video content or periodic aligned RGB images and depth images to localize camera spatial position(s) defined in a three dimensional (3D) coordinate system or reconstruct a 3D virtual representation of a current camera frame in the 3D coordinate system, each in real time.