Lookup Table Depth Map Correction for Multipath Reflections
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Solution Overview
Problem
Time-of-flight cameras face errors in depth map calculations due to multipath reflections, which can lead to significant distortions in measured distances, making real-time operation challenging.
Innovation Solution
A lookup table is used to store corrections for amplitude and phase measurements of light, allowing for accurate depth map generation by applying distance corrections based on precomputed values, reducing the need for processor-intensive calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If processor-intensive calculations are used to correct depth map errors caused by multipath reflections, then measurement precision is improved, but productivity decreases due to the computational load
Solution Approach 1:
The patent precomputes correction values for multipath reflection errors and stores them in lookup tables before real-time operation. During depth map generation, the system simply retrieves precomputed corrections based on measured amplitude and phase values rather than performing intensive calculations, thus maintaining high accuracy while enabling real-time processing
Solution Approach 2:
The patent creates a simplified representation of the complex correction process by storing correction values in lookup tables. Instead of computing corrections on-the-fly, the system copies precomputed correction data from the lookup tables based on input parameters, dramatically reducing computational load while preserving correction accuracy
2Productivity
If simple depth calculation methods are used, then productivity is improved through fast processing, but measurement precision deteriorates due to errors from multipath reflections
Solution Approach 1:
The patent introduces lookup tables as an intermediary between the simple phase-based depth calculation and the complex multipath correction requirements. The lookup tables store precomputed correction values that bridge the gap between fast simple calculations and accurate corrected results, allowing the system to maintain both speed and precision
3Measurement precision
If complex correction algorithms are implemented to address multipath reflections, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the complex correction computations from the real-time processing path and moves them to a precomputation phase. The complex algorithms are executed offline to generate lookup tables, which are then stored and simply queried during operation. This separation removes computational complexity from the operational system while preserving correction accuracy
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 approach enables accurate and efficient real-time depth map correction for multipath reflections, improving the reliability of distance measurements in time-of-flight cameras.
Implementation Method 1
Time-of-flight (TOF) cameras are increasingly used in a variety of applications... A TOF camera can be used to generate depth maps which contain information relating to the depth of an object in a scene from the camera... Given the fact that the speed of light is known, a depth map may be generated
Implementation Method 2
A light source at the TOF camera illuminates the scene and the light is reflected by objects in the scene. The camera receives the reflected light that, dependent on the distance of an object to the camera, experiences a delay
Data Source
AI summary
Depth map correction using lookup tables is described. In an example depth maps may be generated that measure a depth to an object using differences in phase between light transmitted from a camera which illuminates the object and light received at the camera which has been reflected from the object. In various embodiments depth maps may be subject to errors caused by received light undergoing multiple reflections before being received by the camera. In an example a correction for an estimated depth of an object may be computed and stored in a lookup table which maps the amplitude and phase of the received light to a depth correction. In an example the amplitudes and frequencies of each modulation frequency may be to access lookup table which stores corrections for the depth of an object and which allows an accurate depth map to be obtained.