TOF Depth Camera Image Phase Correction via Cosine Error Compensation
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Solution Overview
Problem
The Time of Flight (TOF) principle used in depth cameras introduces optical errors due to cosine errors, leading to inaccuracies in calculating Z-axis distances, which prevents the creation of a correct image on a plane.
Innovation Solution
A method is developed to correct image phases by selecting reference points, calculating standard distances, and using deformation functions to unify offsets and angles, allowing for accurate real distance calculations between the camera and sample points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the TOF principle is used to measure Z-axis distance, then distance measurement capability is achieved, but optical errors cause phase unification failure among shot points
Solution Approach 1:
The patent transforms the measured distances into a standardized coordinate system by applying cosine correction. The correction formula adjusts the measured distance d to a corrected distance d' using the relationship d' = d * cos(θ), where θ is the angle between the optical axis and the line of sight to each shot point. This parameter transformation unifies the phases among all shot points and eliminates the optical errors inherent in the TOF principle.
2Productivity
If distances are calculated using phase-offset formula, then distance values are obtained, but cosine errors prevent correct image formation on a plane
Solution Approach 1:
The patent introduces a standardized coordinate system as an intermediary between the raw TOF measurements and the final image formation. By projecting all shot point distances onto this standardized plane using cosine correction, the system mediates the transformation from three-dimensional spherical coordinates to two-dimensional planar coordinates, enabling accurate flat image creation while preserving the efficiency of TOF distance calculation.
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 ensures the creation of a correct image by correcting image phase errors, enabling precise distance measurements and accurate image formation on a plane.
Implementation Method 1
A common method for measuring the Z-axis distance is to use the principle of time of flight (TOF). Simply speaking, a time period from a light beam emitted by a light source to be reflected by a shot point to come back to the origin can be used to calculate the Z-axis distance.
Data Source
AI summary
A method for correcting an image phase of a depth camera with a lens is disclosed. The method includes the steps of: a) selecting a first reference point on an optical axis of the lens and a second reference point on an object, wherein a distance between the first and second reference points is the shortest than others; b) calculating the distance in the step a) to serve as a standard distance; c) selecting sample points on the object other than the second reference point and calculating distances between the sample points and the first reference point; d) calculating offsets and angles between a line through the first and second reference points and lines through the first reference point and sample points; and e) calculating real distances between the first reference point and sample points by values from the step d).