Time-of-flight camera self-calibration using obstruction reflection
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Solution Overview
Problem
Traditional time-of-flight depth imaging systems require external calibration objects and are not capable of on-the-fly calibration, limiting their flexibility and efficiency in various applications.
Innovation Solution
The implementation of an on-the-fly calibration method that utilizes the placement of an imaging sensor and light source with respect to an obstruction, allowing for self-calibration by measuring signal reflections from a predetermined distance, which can be adjusted, to determine accurate distance measurements and calibrate the system without external objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods using external calibration objects are used, then measurement precision can be achieved, but device complexity and calibration time increase
Solution Approach 1:
The system performs self-calibration by using its own light source and sensor to measure the known distance to the obstruction, eliminating the need for external calibration objects and complex calibration equipment. The ToF camera calibrates itself by capturing images of the obstruction at predetermined distances.
Solution Approach 2:
An obstruction at a predetermined distance serves as an intermediary calibration target. This simple obstruction replaces complex external calibration objects and equipment, providing a known reference distance that enables the system to calibrate its optical path without requiring additional calibration hardware.
2Measurement precision
If traditional calibration methods are used, then measurement precision is achieved, but calibration time and productivity are reduced
Solution Approach 1:
The system performs self-calibration by using its own light source and sensor to measure the known distance to the obstruction, eliminating the need for external calibration objects and complex calibration equipment. The ToF camera calibrates itself by capturing images of the obstruction at predetermined distances.
Solution Approach 2:
The obstruction is pre-positioned at predetermined distances from the light source before calibration begins. This preliminary arrangement of the calibration target at known distances enables the system to perform rapid calibration without requiring complex setup procedures or multiple calibration steps.
3Measurement precision
If external calibration objects are used, then measurement precision is achieved, but adaptability and ease of operation are reduced
Solution Approach 1:
The system performs self-calibration by using its own light source and sensor to measure the known distance to the obstruction, eliminating the need for external calibration objects and complex calibration equipment. The ToF camera calibrates itself by capturing images of the obstruction at predetermined distances.
Solution Approach 2:
The obstruction serves multiple functions: it acts as both the calibration target and a reference for distance measurement. The same simple obstruction can be used for different calibration scenarios and applications, providing universal calibration capability without requiring application-specific calibration objects.
4Measurement precision
If complex calibration systems with external objects are used, then measurement precision is achieved, but cost and manufacturing complexity increase
Solution Approach 1:
The system performs self-calibration by using its own light source and sensor to measure the known distance to the obstruction, eliminating the need for external calibration objects and complex calibration equipment. The ToF camera calibrates itself by capturing images of the obstruction at predetermined distances.
Solution Approach 2:
The obstruction used for calibration is a simple, inexpensive object that can be easily manufactured and replaced. This cheap obstruction replaces expensive external calibration objects and equipment, significantly reducing the cost of the calibration system while maintaining measurement 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
Enables simultaneous calibration of multiple systems, reduces the need for expensive optics, and allows for recalibration at any time, improving the system's accuracy and adaptability in different environments and applications.
Implementation Method 1
an obstruction configured to reflect at least a portion of the emitted light from the light source to at least a subset of the pixels in the sensor array
Data Source
AI summary
An image processing system having on-the-fly calibration uses the placement of the imaging sensor and the light source for calibration. The placement of the imaging sensor and light source with respect to each other affect the amount of signal received by a pixel as a function of distance to a selected object. For example, an obstruction can block the light emitter, and as the obstruction is positioned an increasing distance away from the light emitter, the signal level increases as light rays leave the light emitters, bounce off the obstruction and are received by the imaging sensor. The system includes a light source configured to emit light, and an image sensor to collect incoming signals including reflected light, and a processor to determine a distance measurement at each of the pixels and calibrate the system.