TOF Camera Distance Correction Using Reference Object Feature Points
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Solution Overview
Problem
Time-of-flight (TOF) cameras experience distance measurement errors due to individual characteristic variations and aging of electronic elements, which are exacerbated by environmental factors like temperature changes, and existing solutions with temperature sensors do not fully address these issues.
Innovation Solution
A distance measuring apparatus that includes a light emitting section, two-dimensionally arranged light receiving elements, and a correction mechanism using a reference object with feature points to calculate a correction amount for accurate distance correction, allowing for continuous monitoring and adjustment of distance measurement values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed under specific conditions at shipment, then individual characteristic variations are adjusted within target error ranges, but distance measurement errors increase due to temperature changes and aging
Solution Approach 1:
The system performs preliminary calibration at shipment to establish baseline correction values for individual characteristic variations. Additionally, it periodically captures reference object images during operation to recalculate correction amounts, proactively compensating for drift before it affects measurement accuracy.
Solution Approach 2:
The system continuously monitors distance measurements of a reference object with known dimensions and feeds this information back to recalculate correction amounts. This closed-loop feedback mechanism dynamically adjusts for temperature changes and aging effects, maintaining measurement reliability over time.
2Reliability
If temperature sensors are mounted inside the TOF camera to detect fluctuations, then temperature-based corrections can be applied, but position and accuracy issues of the temperature sensor remain
Solution Approach 1:
Instead of directly measuring temperature with sensors inside the camera, the system uses the reference object as an intermediary. The reference object's known dimensions serve as a mediator to indirectly detect and correct for environmental effects including temperature, avoiding the positioning and accuracy problems of internal temperature sensors.
Solution Approach 2:
The system replaces the mechanical/physical temperature sensing approach with an optical measurement approach. By using the reference object's reflected light and known geometry, the system substitutes direct thermal measurement with optical-based dimensional verification, eliminating temperature sensor placement issues.
3Measurement precision
If a reference object with feature points is used to calculate correction amounts, then distance measurement errors are corrected, but additional processing time and complexity are introduced
Solution Approach 1:
The reference object is pre-configured with known three-dimensional coordinate correlations and feature points before use. This preliminary preparation allows the system to directly compare captured images against predetermined reference data, simplifying the correction calculation process while maintaining high accuracy.
Solution Approach 2:
The system creates a digital copy or model of the reference object with known dimensional characteristics. By comparing the captured image against this predetermined reference model, the system efficiently calculates correction amounts without requiring complex real-time analysis, reducing processing complexity while maintaining precision.
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
The apparatus effectively corrects distance measurement errors caused by individual characteristic variations and aging, maintaining accuracy over time by using a reference object to calculate and apply a correction amount, thereby improving the reliability of distance measurements.
Implementation Method 1
a distance measuring apparatus which measures a distance to an object based on a time of flight of light
Implementation Method 2
a plurality of light receiving elements which are two-dimensionally arranged and which receive incident light from the target measurement space
Data Source
AI summary
A distance measuring apparatus includes a reference object distance calculation section which calculates a distance to a reference object based on a two-dimensional image in which the reference object, which includes a plurality of feature points having obvious three-dimensional coordinate correlations, is captured, and a correction amount calculation section which calculates a correction amount for correcting a distance image by comparing the calculated distance to the reference object with a distance measurement value to the reference object in the distance image.