Analytical-adaptive multifrequency error minimization unwrapping

Patent metadata

Field	Value
Publication number	US-2019302244-A1
Application number	US-201815941885-A
Country	US
Kind code	A1
Filing date	Mar 30, 2018
Priority date	Mar 30, 2018
Publication date	Oct 3, 2019
Grant date	—

Abstract

Features of the present disclosure implement an analytical formalism to calculate a time of flight (ToF) for a signal in order to identify the distance between the ToF imaging system and a target object. The features of the present disclosure allow a flexible, fast, and accurate solution for phase unwrapping in ToF imaging system. Such techniques minimize the memory usage, accounts for the factors that generally contribute to differences in the performance of the selected modulation frequencies, and mitigates the unwrapping errors that occur in low signal to noise areas.

First claim

What is claimed is:

1 . A method for signal processing in a time of flight (ToF) system, comprising:
emitting, from the ToF system, a signal towards a target object at a first time period; detecting, at a second time period, the signal reflected off a surface of the target object by an imaging pixel detector of the ToF system, wherein the signal is associated with a selected pixel in an image from the target object; calculating a time of flight between the first time period and the second time period based on an analytical formulation to unwrap a phase of the signal, wherein the time of flight is independent of a modulation frequency used for the signal; and outputting a distance between the ToF system and the target object based on the calculated time of flight for the signal.

2 . The method of claim 1 , wherein calculating the time of flight between the first time period and the second time period comprises:
analyzing the signal from the selected pixel of the image captured by the signal to identify the time of flight, wherein analyzing the signal comprises excluding information from another pixel in the image for calculating the time of flight of the signal.

3 . The method of claim 2 , wherein the time of flight is calculated by a ToF calculation module applying the following equation to the signal:

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wherein:
f k is modulation frequency,
à k (m, n) is an amplitude of the signal for the selected pixel, and
Ø k (m, n) is a phase of the signal for the selected pixel.

4 . The method of claim 1 , wherein calculating the time of flight between the first time period and the second time period comprises:
identifying one or more neighboring pixels to the selected pixel for which the ToF is being analyzed based on the detected signal; and receiving a neighboring time of flight information for the one or more neighboring pixels in order to identify the time of flight for the signal for the selected pixel.

5 . The method of claim 4 , wherein the time of flight for the signal is calculated by a ToF calculation module applying the following equation to the signal:

t
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Assignees

• Microsoft Technology Licensing Llc

Inventors

• Egea Sergio Ortiz

Classifications

• G01S17/894

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title

• G01S17/26

  wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals · CPC title

• G01S17/931

  of land vehicles · CPC title

• G01S7/4865 Primary

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S17/89

  for mapping or imaging · CPC title