Time-of-Flight Camera Distance Accuracy via Intensity Analysis
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Solution Overview
Problem
Time-of-flight cameras face inaccuracies in distance measurement due to light paths varying before reaching objects, leading to overestimated distances, and struggle to differentiate between portions of an object with different reflectance.
Innovation Solution
An image system comprising a light source, an image sensing device, and a computing apparatus that determines intensity values and distances between object portions, using these values to calculate accurate distances and reflectance, and construct three-dimensional images, while accounting for variations in light paths and object reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light pulses are used to illuminate the complete scene in a time-of-flight camera, then distance data can be created using the time-of-flight principle, but light may go through different paths before reaching objects causing the estimated distance to be greater than the actual distance
Solution Approach 1:
The patent divides the scene into multiple depth ranges or distance zones. By segmenting the measurement space, the system can apply different processing or filtering techniques to different depth regions, reducing the impact of multi-path interference on overall distance measurement accuracy.
Solution Approach 2:
The system uses feedback mechanisms to iteratively refine distance measurements. By comparing initial distance estimates with expected values or using multiple measurements, the system can correct errors caused by light taking different paths, thereby improving measurement precision.
2Adaptability or versatility
If light illuminates the complete scene, then all objects can be captured, but it is difficult to differentiate between portions of an object with different reflectance
Solution Approach 1:
The patent applies local quality by using multiple wavelengths or frequency components of light to illuminate different portions of the scene. This allows the system to differentiate between materials with different reflectance properties at each location, while still maintaining complete scene coverage through the composite illumination approach.
Solution Approach 2:
The system changes parameters such as wavelength, frequency, or polarization state of the illumination light to enhance the contrast between different materials. By modulating these parameters, the system can differentiate portions of objects with different reflectance while maintaining comprehensive scene illumination.
3Measurement precision
If analog timing imagers use fast switches and memory elements to convert light into current signals, then distance information can be captured, but the device complexity increases
Solution Approach 1:
The patent merges the timing imager functionality with standard image sensor architectures. By integrating distance measurement capabilities into existing sensor frameworks, the system reduces device complexity while maintaining the ability to capture distance information through coordinated operation of illumination and detection components.
Solution Approach 2:
The system employs universal components that can perform multiple functions. For example, standard image sensors are used for both intensity imaging and distance measurement when combined with appropriate illumination schemes, eliminating the need for completely separate specialized hardware and thereby reducing overall device complexity.
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 system provides accurate distance measurements and reflectance analysis, enabling precise three-dimensional imaging and motion detection by analyzing intensity values and distances, reducing errors caused by varying light paths and object reflectance.
Implementation Method 1
The camera has photo diodes (PDs), which convert incoming light into currents
Implementation Method 2
A time-of-flight camera (TOF camera) is a camera system that creates distance data with the time-of-flight (TOF) principle
Data Source
AI summary
An image system comprises a light source, an image sensing device, and a computing apparatus. The light source is configured to illuminate an object comprising at least one portion. The image sensing device is configured to generate a picture comprising an image. The image is produced by the object and comprises at least one part corresponding to the at least one portion of the object. The computing apparatus is configured to determine an intensity value representing the at least one part and to determine at least one distance between the at least one portion and the image sensing device using the intensity value and a dimension of the at least one part of the image.