US 10,884,109 B2Granted

Analytical-adaptive multifrequency error minimization unwrapping

AssigneeMicrosoft Technology Licensing, LLC

InventorSergio Ortiz Egea

Life of this patent

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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.

Claims16

Dependent claims

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, wherein the time of flight is calculated by a ToF calculation module applying the following equation to the signal:
t
=
∑
k
=
1
K
⁢
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
⁢
t
~
k
⁡
(
m
,
n
)
∑
k
=
1
K
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
=
∑
k
=
1
K
⁢
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
⁢
ϕ
~
k
⁡
(
m
,
n
)
∑
k
=
1
K
⁢
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
wherein
fk is modulation frequency,
Ãk (m, n) is an amplitude of the signal for the selected pixel, and Øk (m, n) is a phase of the signal for the selected pixel;
and
outputting a distance between the ToF system and the target object based on the calculated time of flight for the signal.

107 more elements

A computer device for signal processing in a time of flight (ToF) system, comprising:

a memory to store data and instructions;
and
a processor in communication with the memory to execute the instructions to:
emit, from the ToF system, a signal towards a target object at a first time period;
detect, 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;
calculate 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, wherein the time of flight for the signal is calculated by a ToF calculation module applying the following equation to the signal:
t
⁡
(
m
,
n
)
=
∑
k
=
1
K
⁢
f
k
⁢
∑
i
=
m
-
I
m
+
I
⁢
∑
j
=
n
-
J
n
+
J
⁢
λ
⁡
(
i
,
j
)
⁢
A
~
k
⁡
(
i
,
j
)
⁢
t
~
k
⁡
(
i
,
j
)
∑
k
=
1
K
⁢
f
k
⁢
∑
i
=
m
-
I
m
+
I
⁢
∑
j
=
n
-
J
n
+
J
⁢
λ
⁡
(
i
,
j
)
⁢
A
~
k
⁡
(
i
,
j
)
wherein
fk is modulation frequency,
Ãk (i, j) is an amplitude of the signals for the one or more neighboring pixels to the selected pixel, and
λ (i, j) is a normalized weighting coefficients for the one or more neighboring pixels to the selected pixel;
and
output a distance between the ToF system and the target object based on the calculated time of flight for the signal.

119 more elements

A storage device storing instructions executable by a computer device for signal processing in a time of flight (ToF) system, the instructions comprising code for:

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, wherein the time of flight is calculated by a ToF calculation module applying the following equation to the signal:
t
=
∑
k
=
1
K
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
⁢
t
~
k
⁡
(
m
,
n
)
∑
k
=
1
K
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
=
∑
k
=
1
K
⁢
f
k
⁢
A
~
k
⁡
(
m
,
n
)
⁢
ϕ
~
k
⁡
(
m
,
n
)
∑
k
=
1
K
⁢
f
k
2
⁢
A
~
k
⁡
(
m
,
n
)
wherein
fk is modulation frequency,
Ãk(m, n) is an amplitude of the signal for the selected pixel, and Øk (m, n) is a phase of the signal for the selected pixel;
and
outputting a distance between the ToF system and the target object based on the calculated time of flight for the signal.

103 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/941,885Filed 30 Mar 2018
Published: US 2019/0302244 A13 Oct 2019
Granted: 5 Jan 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01S 7/4865
Receivers: time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak
G01S 17/26
Using transmission of interrupted, pulse-modulated waves: wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier…
G01S 17/89
Lidar systems specially adapted for specific applications: for mapping or imaging
G01S 17/894
For mapping or imaging: three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver…

Family

US 2019/0302244 A1Pre-grant publication · published 3 Oct 2019
US 10,884,109 B2This patent

From the US filing history. Foreign family members aren’t listed.

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Abstract

Facts

Application

15/941,885Filed 30 Mar 2018

Published

US 2019/0302244 A13 Oct 2019

Granted

5 Jan 2021

Term ends

Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01S 7/4865
Receivers: time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak
G01S 17/26
Using transmission of interrupted, pulse-modulated waves: wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier…
G01S 17/89
Lidar systems specially adapted for specific applications: for mapping or imaging
G01S 17/894
For mapping or imaging: three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver…