Periodic Illumination Pattern for Depth Measurement Precision
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Solution Overview
Problem
Existing depth-from-photon-ratio (DPR) techniques face challenges in accurately determining the position of objects, especially with high point densities of laser point patterns, unknown reflective objects, estimating orientation of reflecting surfaces, and analyzing laser spots on sharp edges.
Innovation Solution
A detector system comprising a projector that generates a periodic illumination pattern with spatially modulated features, and a sensor element with a matrix of optical sensors to determine reflection images and longitudinal coordinates using a depth-from-photon-ratio technique.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard illumination pattern is used for depth measurement, then the system is simple to operate, but measurement precision deteriorates in the presence of unknown reflective materials and complex surface orientations
Solution Approach 1:
The patent applies parameter changes by modulating the illumination pattern with specific spatial frequencies and orientations. The projector displays patterns with varying frequencies and orientations sequentially, and the detector measures reflectance at these different parameters. This allows the system to extract depth information that is independent of material reflectivity properties, thereby improving measurement precision without requiring complex additional hardware.
Solution Approach 2:
The patent uses periodic action by sequentially projecting illumination patterns with different spatial frequencies and orientations. The system cycles through multiple patterns with varying parameters, measuring reflectance at each stage. This periodic variation in illumination parameters enables the detection to disambiguate between depth variations and material reflectivity variations, improving depth measurement precision while maintaining system simplicity.
2Productivity
If laser point density is increased to improve coverage, then productivity increases, but measurement precision deteriorates due to noise in DPR evaluation and correspondence problem solvability
Solution Approach 1:
The patent resolves the correspondence problem by using periodic illumination patterns with specific spatial frequencies. The known structure of these patterns allows the system to identify corresponding points between the projected pattern and the reflected pattern detected by the sensor, even at high point densities. This periodic structuring enables reliable depth determination without sacrificing productivity.
3Device complexity
If DPR technique is used for distance determination, then device complexity is reduced to a single camera system, but measurement precision deteriorates due to noise and correspondence problem
Solution Approach 1:
The patent improves DPR measurement precision by introducing parameter changes in the illumination patterns. By varying the spatial frequency and orientation of the projected patterns and measuring reflectance at these different parameters, the system can extract depth information that is robust against noise and independent of material reflectivity properties. This allows a single-camera system to achieve higher measurement precision without increasing 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 achieves enhanced precision in determining object positions with low technical effort and resource requirements, effectively addressing the challenges of high point densities, unknown reflective materials, and complex surface orientations.
Implementation Method 1
each optical sensor has at least one light sensitive area, wherein each optical sensor is designed to generate at least one sensor signal in response to an illumination of its respective light-sensitive area by the light beam
Data Source
AI summary
Disclosed herein is a detector for determining a position of at least one object. The detector includes at least one projector for illuminating the object, at least one sensor element, and at least one evaluation device.