Three dimensional ladar imaging and methods using voxels

• US 8,587,637 B1
• Filed: 05/07/2010
• Issued: 11/19/2013
• Est. Priority Date: 05/07/2010
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation), FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation), FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Woolaway, James T., Cryder, Michael E., Tatko, Henry J, Schlesselmann, John D.
• Primary Examiner(s): Czekaj, David
• Assistant Examiner(s): SULLIVAN, TYLER
• Application Number:
  US12/775,868
• Time in Patent Office: 1,292 Days
• Field of Search: None
• US Class Current: 348/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/4865 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 Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/271 wherein the generated image signals comprise depth maps or disparity maps

Abstract

Various techniques are provided for forming three-dimensional images. For example, in one embodiment, a system for three-dimensional imaging of an object includes an imaging sensor that provides a focal plane array and a sensor controller. The system also includes a laser illuminator coupled to the sensor controller. The laser illuminator is adapted to emit at least one laser pulse to be reflected from at least one plane of the object and detected by the focal plane array as at least one two-dimensional image frame of light intensities. The sensor controller is adapted to associate a range dimension of the plane with the image frame to facilitate formation of a three-dimensional image of the object. Related methods are also contemplated.

Claims

1. A system for three-dimensional imaging of an object comprising:

an imaging sensor comprising a focal plane array and a sensor controller; and

a laser illuminator coupled to said sensor controller;

wherein said laser illuminator is adapted to emit

at least one laser pulse to be reflected from at least one plane of said object and detected by said focal plane array as at least one two-dimensional image frame of light intensities so as to provide range information and relative contrast information of said plane of said object, wherein said sensor controller is

adapted to associate a range dimension of said plane with said two-dimensional image frame to facilitate formation of a three-dimensional image of said object, and wherein said sensor controller is adapted to activate and deactivate said sensor, to generate from a single laser pulse a single two-dimensional image frame for a single time period wherein each said two-dimensional image frame includes an array of three dimensional volume pixels associated

with said plane of said object, wherein successive single laser pulses generate successive two-dimensional image frames, and wherein said two-dimensional image frames collectively provide a three dimensional array of said volume pixels to provide a three dimensional image of the object.

2. The system of claim 1, wherein said two-dimensional image frame is a two-dimensional array of voxels (volume pixels), each of said voxels having a height dimension, a width dimension and a length dimension.

3. The system of claim 2, wherein said sensor controller associates said range dimension with said two-dimensional array of voxels to facilitate formation of said three-dimensional image of said object.

4. The system of claim 1, wherein said sensor controller is adapted to activate said focal plane array just before arrival at said focal plane array of said two-dimensional image frame, and deactivate said focal plane array just after said focal plane array detects said two-dimensional image frame.

5. The system of claim 1, wherein said sensor controller is adapted to generate a synchronization signal to initiate transmission of said laser pulse upon receipt of said synchronization signal by said laser illuminator, said sensor controller configured to determine a time at which said two-dimensional image frame associated with said emitted laser pulse is to arrive at said focal plane array, such that said sensor controller transitions said focal plane array from an inactive state after said laser pulse is transmitted to an active state at said determined time of arrival of said two-dimensional image frame at said focal plane array.

6. The system of claim 1, wherein said two-dimensional image frame associated with said plane of said object is formed from a plurality of laser pulses.

7. The system of claim 1, further comprising:

an interface coupled to said imaging sensor to transfer said two-dimensional image frame detected by said imaging sensor.

8. The system of claim 1, wherein said sensor controller is adapted to determine said range dimension of said plane.

9. The system of claim 1, wherein said focal plane array comprises discrete sensing regions configured to detect different wavelengths associated with said two-dimensional image frame.

10. The system of claim 9, wherein said discrete sensing regions comprise a first region formed of indium gallium arsenide (InGaAs) and a second region formed of indium antimonide (InSb).

11. The system of claim 1, wherein said focal plane array comprises an array of unit cells, each said unit cell comprising:

a detector adapted to generate a current in response to detection of said two-dimensional image frame;

an integrator circuit adapted to receive said current from said detector, said integrator circuit configured to provide a first voltage in response to said receipt of said current, wherein said first voltage is adapted to be selectively reset before said current is received from said detector;

a sample and hold (S/H) circuit adapted to sample a second voltage, wherein said second voltage is associated with said first voltage; and

a buffer adapted to provide said second voltage to be read out from each said unit cell.

12. A method for generating a three-dimensional image of an object comprising:

emitting a single laser pulse to be reflected from at least one plane of said object;

detecting said reflected laser pulse as a two-dimensional image frame of light intensities with a sensor so as to provide range information and relative contrast information of said plane of said object;

activating and deactivating said sensor for a single time period to generate said two-dimensional image frame associated with said at least one plane of said object;

identifying a range dimension of said plane corresponding with said two-dimensional image frame;

associating said two-dimensional image frame with said range dimension of said corresponding plane such that each said two-dimensional image frame includes an array of three-dimensional volume pixels; and

repeating the emitting, detecting, activating, identifying, and associating steps so as to build a plurality of composite image frames from said successive plurality of two-dimensional image frames to form a three-dimensional image of said object.

13. The method of claim 12, wherein a time at which said detecting occurs is at least partially determined by said range dimension of said plane of said object from a source of said laser pulse.

14. The method of claim 12, wherein at said emitting, one laser pulse is emitted, and at said detecting a plurality of two-dimensional image frames of light intensities are detected.

15. The method of claim 12, further comprising:

transferring said three-dimensional image to a display.

16. The method of claim 12, further comprising:

estimating a time of receipt of said two-dimensional image frame after said emitting; and

performing said detecting at said estimated time.

17. A method for generating a three-dimensional image of an object comprising:

providing an imaging system comprising a laser illuminator coupled to an imaging sensor, said laser illuminator configured to emit a laser pulse for receipt by said imaging sensor;

identifying a range dimension defined as a distance between said laser illuminator and said object;

emitting from said laser illuminator a single laser pulse to be reflected from said object;

detecting said reflected laser pulse as a two-dimensional image frame of light intensities at said imaging sensor so as to provide range information and relative contrast information of said plane of said object;

repeating the emitting and detecting steps in conjunction with activating and deactivating said imaging sensor to generate a plurality of said two-dimensional image frames, wherein each said two-dimensional image frame is associated with said at least one plane of said object;

associating said two-dimensional image frame with said range dimension such that each said two-dimensional image frame includes an array of three-dimensional volume pixels; and

building a plurality of composite image frames from said plurality of two-dimensional image frames collectively provide a three-dimensional array of said volume pixels to form a three-dimensional image of the object.

18. The method of claim 17, wherein a time at which said detecting occurs is at least partially determined by said range dimension associated with said two-dimensional image frame.

19. The method of claim 17, further comprising:

estimating a delay period defined as a time elapsing for said laser pulse emitted from said laser illuminator to propagate from said laser illuminator to said object and reflect from said object back to said imaging sensor as said two-dimensional image frame; and

activating said imaging sensor after expiration of said delay period.

20. The method of claim 19, further comprising:

deactivating said imaging sensor after said detecting.