Optical 3D Measurement Using Triangulation and TOF Switching
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Solution Overview
Problem
Optical distance cameras face challenges with extreme dynamic range of background illuminance, inability to determine distances to unstructured surfaces using triangulation, and erroneous distance measures due to multi-path effects in time-of-flight techniques.
Innovation Solution
An optical distance camera system with multiple transceiver modules, each comprising a modulated light source, beam splitter, and two cameras: one for triangulation and one for time-of-flight, allowing adaptive operation modes to handle varying illuminance conditions, combining triangulation and TOF techniques for reliable 3D imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If triangulation technique is used for 3D imaging, then distance measurement is possible with simple equipment, but it cannot determine distances to unstructured surfaces
Solution Approach 1:
The patent combines triangulation and TOF techniques into a single optical distance camera system. The device integrates both measurement methods, allowing it to use triangulation for structured surfaces and TOF for unstructured surfaces, thus resolving the limitation of triangulation while maintaining equipment simplicity.
Solution Approach 2:
The optical distance camera is designed to perform multiple functions: it can measure both structured and unstructured surfaces by switching between triangulation and TOF techniques. This multi-functionality allows the device to handle diverse measurement scenarios without requiring separate specialized equipment.
2Reliability
If TOF technique is used for 3D imaging, then distance measurement works on unstructured surfaces, but multi-path effects cause erroneous distance measures
Solution Approach 1:
The patent uses structured illumination patterns as an intermediary to disambiguate multi-path effects. By projecting known patterns and analyzing their distortion, the system can identify and correct erroneous TOF measurements caused by multi-path reflections, thus improving measurement precision while maintaining the ability to measure unstructured surfaces.
Solution Approach 2:
The system merges triangulation and TOF measurements, using triangulation to verify and correct TOF results in areas affected by multi-path effects. This combination allows the device to maintain high measurement precision while preserving the capability to measure unstructured surfaces that triangulation alone cannot handle.
3Adaptability or versatility
If optical distance camera operates in uncontrolled outdoor environments, then it can navigate in real world, but extreme variations in background illuminance make measurement difficult
Solution Approach 1:
The patent implements dynamic adaptation of measurement parameters based on detected background illuminance levels. The system automatically adjusts exposure times, gain settings, and switches between triangulation and TOF modes according to lighting conditions, enabling accurate measurements across extreme illuminance variations from full daylight to starlight.
Solution Approach 2:
The optical distance camera changes operational parameters including light source intensity, integration time, and measurement mode based on ambient illuminance conditions. This parameter adaptation allows the device to maintain measurement precision across a wide dynamic range of outdoor lighting environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable 3D imaging across a wide range of illuminance levels from full daylight to starlit night, overcoming limitations of triangulation on unstructured surfaces and TOF multi-path errors by dynamically switching between triangulation and TOF methods.
Implementation Method 1
a light source whose intensity can be temporally modulated
Implementation Method 2
the second camera consists of pixels that are each capable of sensing and demodulating incident modulated light, back-reflected from the objects in the scene
Implementation Method 3
a beam splitter directing the reflected light into a first and a second camera
Data Source
AI summary
An optical measurement system includes a first optical transceiver including a first light source, a first camera, a second camera, and a first beam splitter, and a second optical transceiver including a second light source, a third camera, a fourth camera, and a second beam splitter. The optical measurement system operates in at least one operation mode including a first operation mode. In the first operation mode, the first camera and the third camera are employed to determine a three-dimensional shape of an environment using a triangulation technique, and at least one of the second camera and the fourth camera is employed to determine the three-dimensional shape of the environment using a time-of-flight technique.