3D Camera Depth Calibration Using Phase Value Prediction
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Solution Overview
Problem
Existing 3D cameras face challenges in precise calibration due to the inclusion of non-two-dimensional information in images, such as ceilings and walls, which affects the accuracy of depth information when testing distances exceed standard distances, making it difficult to achieve accurate depth measurement.
Innovation Solution
A method for calibrating 3D camera depth involves establishing a communication connection between a computer device and the 3D camera, using a calibration plane with uniform material, acquiring phase values at standard and testing distances, intercepting phase values of two-dimensional image regions, calculating predicted phase values for non-two-dimensional image regions, and applying a fitting algorithm to correct depth information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the testing distance exceeds the standard distance, then the measurement range is extended, but the image contains non-two-dimensional information (ceiling, ground, walls) which degrades measurement precision
Solution Approach 1:
The patent segments the image into two-dimensional image regions and non-two-dimensional image regions. By dividing the image space and applying different processing methods to different regions, the system can handle extended testing distances while maintaining precision for the primary calibration plane.
Solution Approach 2:
The patent extracts and removes non-two-dimensional information from the image data. By identifying and eliminating regions corresponding to ceiling, ground, and wall information, the system prevents these harmful factors from degrading the depth measurement accuracy.
2Length of stationary object
If direct measurement of short distance is attempted, then the measurement range covers short distances, but the fast speed of laser makes it difficult to realize accurate measurement
Solution Approach 1:
The patent uses periodic phase modulation of the laser signal to measure short distances. By modulating the laser at known frequencies and measuring phase differences between emitted and reflected light, the system can accurately determine very short flight times that would be impossible to measure directly.
3Length of stationary object
If phase difference measurement is used to determine object position, then short distance measurement becomes possible, but the calibration process becomes complex due to phase value variations across different distances
Solution Approach 1:
The patent changes the parameter being measured from direct time of flight to phase difference. By using phase modulation and measuring the phase shift of the reflected signal, the system can determine short distances with high precision while managing calibration complexity through mathematical relationships between phase and distance.
Solution Approach 2:
The patent replaces direct mechanical/time-based measurement with optical phase measurement. By using light wave phase properties instead of direct time measurement, the system achieves high precision for short distances while the calibration complexity is managed through optical physics principles.
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
This method enables accurate calibration of 3D camera depth by isolating two-dimensional image regions, correcting non-two-dimensional image region phase values, and integrating predicted phase values to improve the precision of depth information across varying distances.
Implementation Method 1
The distance between the object and the camera is obtained by measuring the optical flight time of the 3D camera, specifically, a laser pulse is continuously emitted to the object by the 3D camera, and then the reflected light is received by the sensor, and the exact distance of the target is obtained by detecting the round-trip time of the laser pulse.
Implementation Method 2
because speed of laser is very fast, it is difficult to realize a short distance between the object and the 3D camera by any direct measurement. Therefore, the object observed can be determined by measuring the phase difference between emitted and reflected light.
Data Source
AI summary
A method for calibrating a depth of a 3D camera includes selecting a calibration plane and obtaining a first depth image of the calibration plane using a 3D camera when a distance between the 3D camera and a calibration plane is a standard distance. A first depth image, represented by a first phase values of pixel points, is obtained. Then obtaining a second depth image of the calibration plane using the 3D camera when a distance is a testing distance, and intercepting the phase values of the pixel points of the two-dimensional image region and deleting the phase values of the pixel points of the non two-dimensional image region in the second depth image. Calculating and outputting predicted phase values of pixel points in the non two-dimensional image region of the second depth image and calibrating the second depth image.