Hybrid SLAM Tracking Rotation-Only Motion Parallax

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Solution Overview

Problem

Visual SLAM systems face challenges with rotation-only camera motion, leading to stalled tracking and failed camera localization due to the lack of newly selected keyframes, as they require sufficient parallax for feature triangulation, which is not available during pure rotational movements.

Innovation Solution

The Hybrid SLAM system combines 6DOF SLAM and Panorama SLAM to dynamically switch between modes based on camera motion, allowing seamless tracking and mapping during rotations by utilizing both finite and infinite depth features, enabling the creation of a robust 3D map that includes keyframes with rotational constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If keyframe-based visual SLAM systems use structure-from-motion techniques to create 3D feature maps, then 3D mapping capability is improved, but tracking fails during rotation-only camera motion due to lack of parallax

Engineering Contradiction:
Improvetracking reliabilityVSAvoidadaptability to rotation-only motion
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically switches between two operational modes: 6DOF SLAM mode for general camera motion and Panorama SLAM mode for rotation-only motion. This dynamic adaptation allows the system to maintain reliable tracking across different motion types by selecting the appropriate algorithmic approach based on current camera movement characteristics

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes key parameters based on motion type: during rotation-only motion, it switches to Panorama SLAM which uses 3DOF pose estimation and infinite depth features instead of the standard 6DOF approach with finite depth features. This parameter change enables the system to handle rotation-only scenarios where parallax is insufficient

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If visual SLAM systems require sufficient parallax for feature triangulation, then 3D feature mapping accuracy is improved, but keyframe selection rejects rotation-only motion frames causing tracking stall

Engineering Contradiction:
Improvefeature triangulation precisionVSAvoidkeyframe selection rate
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system segments the feature space into two distinct types: finite depth features for 6DOF SLAM and infinite depth features for Panorama SLAM. This segmentation allows the system to maintain appropriate feature representations for different motion modes, preventing rejection of rotation-only frames while preserving triangulation accuracy when applicable

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Infinite depth features act as an intermediary representation that bridges the gap during rotation-only motion. These features allow the system to track and map during panorama movements without requiring the parallax-based triangulation that would otherwise reject such frames, thereby maintaining productivity

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If camera tracking uses 6DOF SLAM with finite depth features, then general camera motion tracking is improved, but system fails in unmapped regions during rotation-only motion

Engineering Contradiction:
Improvecamera tracking reliabilityVSAvoidhandling of unmapped regions
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system implements a universal SLAM framework that can handle both mapped and unmapped regions across different motion types. By integrating 6DOF SLAM and Panorama SLAM, the system achieves multi-functionality: it can track general camera motion in mapped regions and rotation-only motion in unmapped regions, eliminating the failure mode of traditional systems

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

Data Source

PatentUS9674507B2Monocular visual SLAM with general and panorama camera movements
Publication Date: 2017.06.06 QUALCOMM INC
  • US9674507B2 patent drawing
  • US9674507B2 patent drawing
  • US9674507B2 patent drawing

AI summary

Disclosed are a system, apparatus, and method for monocular visual simultaneous localization and mapping that handles general 6DOF and panorama camera movements. A 3D map of an environment containing features with finite or infinite depth observed in regular or panorama keyframes is received. The camera is tracked in 6DOF from finite, infinite, or mixed feature sets. Upon detection of a panorama camera movement towards unmapped scene regions, a reference panorama keyframe with infinite features is created and inserted into the 3D map. When panoramic camera movement extends toward unmapped scene regions, the reference keyframe is extended with further dependent panorama keyframes. Panorama keyframes are robustly localized in 6DOF with respect to finite 3D map features. Localized panorama keyframes contain 2D observations of infinite map features that are matched with 2D observations in other localized keyframes. 2D-2D correspondences are triangulated, resulting in new finite 3D map features.