Unsynchronized Structured Lighting 3D Capture

Solution Overview

Problem

Existing three-dimensional shape capture systems based on structured lighting require synchronization between the camera and projector, limiting their use and increasing costs, especially when using rolling shutter image sensors.

Innovation Solution

A system and method that allows for unsynchronized operation between the pattern projector and camera, enabling the use of inexpensive cameras and various computing hardware by synthesizing synchronized image frames from unsynchronized patterns, supporting both global and rolling shutter image sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If synchronization between camera and projector is required, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improve3D shape capture accuracyVSAvoidsynchronization system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies this principle by using inexpensive, commercially available cameras (such as smartphone cameras, webcams, or consumer digital cameras) instead of expensive synchronized industrial camera-projector systems. The method compensates for the lack of synchronization through computational techniques, allowing the use of cheap, unsynchronized devices while maintaining measurement capability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the operational parameters by allowing the camera and projector to operate at different frame rates and without synchronization. The system captures images at the camera's native frame rate while the projector operates independently, and uses computational methods to associate captured images with the appropriate projected patterns based on temporal overlap analysis rather than strict synchronization.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If synchronized operation is used, then three-dimensional shape capture accuracy is improved, but capital investment costs increase

Engineering Contradiction:

Improvethree-dimensional shape capture accuracyVSAvoidcapital investment cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies this principle by using inexpensive, commercially available cameras (such as smartphone cameras, webcams, or consumer digital cameras) instead of expensive synchronized industrial camera-projector systems. The method compensates for the lack of synchronization through computational techniques, allowing the use of cheap, unsynchronized devices while maintaining measurement capability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces the mechanical/electronic synchronization system with a computational approach. Instead of using hardware triggers and synchronized clock signals, the system uses software-based temporal overlap analysis to match captured images with projected patterns, substituting computational processing for physical synchronization mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If rolling shutter image sensors are used, then device cost is reduced, but synchronization requirements become more complex

Engineering Contradiction:

Improvecamera costVSAvoidsynchronization complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent changes the operational parameters by allowing the camera and projector to operate at different frame rates and without synchronization. The system captures images at the camera's native frame rate while the projector operates independently, and uses computational methods to associate captured images with the appropriate projected patterns based on temporal overlap analysis rather than strict synchronization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies dynamics by making the association between captured images and projected patterns flexible and adaptive rather than rigid and fixed. The system dynamically determines which pattern corresponds to which image based on temporal overlap analysis, allowing the relationship to vary with different camera frame rates, rolling shutter speeds, and projection timing without requiring pre-established synchronization.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11425358B2Method and system for unsynchronized structured lighting

Publication Date: 2022.08.23 BROWN UNIVERSITY

AI summary

A system and method to capture the surface geometry a three-dimensional object in a scene using unsynchronized structured lighting is disclosed. The method and system includes a pattern projector configured and arranged to project a sequence of image patterns onto the scene at a pattern frame rate, a camera configured and arranged to capture a sequence of unsynchronized image patterns of the scene at an image capture rate, and a processor configured and arranged to synthesize a sequence of synchronized image frames from the unsynchronized image patterns of the scene. Each of the synchronized image frames corresponds to one image pattern of the sequence of image patterns.