Imaging systems and methods including obscurant characterization

• US 10,416,470 B2
• Filed: 10/31/2017
• Issued: 09/17/2019
• Est. Priority Date: 02/18/2016
• Status: Active Grant

• Current Assignee: L3harris Cincinnati Electronics Corporation (L3Harris Technologies, Inc.)
• Original Assignee: L3 Cincinnati Electronics Corp. (L3Harris Technologies, Inc.)
• Inventors: Hiriyannaiah, Harish P., Tang, Nansheng
• Primary Examiner(s): Punnoose, Roy M
• Application Number:
  US15/798,766
• Publication Number:
  US 20180052333A1
• Time in Patent Office: 686 Days
• Field of Search: 356438, 356432, 356364
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels
• CPC Class Codes: G02B 27/281 used for attenuating light intensity, e.g. comprising rotatable polarising elements
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 27/288 Filters employing polarising elements, e.g. Lyot or Solc filters G02B5/3016 takes precedence
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06F 18/22 Matching criteria, e.g. proximity measures
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 10/75 Organisation of the matching processes, e.g. simultaneous or sequential comparisons of image or video features; Coarse-fine approaches, e.g. multi-scale approaches; using context analysis; Selection of dictionaries

Abstract

Systems and methods for characterizing an obscurant and imaging a target are disclosed. In one embodiment, a method of imaging a target includes characterizing at least one obscurant present in an environment, and determining, based on the at least one characterized obscurant, one or more of the following: one or more wavelengths corresponding to the at least one obscurant, a polarization state corresponding to the at least one obscurant, and a sensor exposure time corresponding to the at least one obscurant. The method further includes adjusting one or more parameters of an imagining system based at least in part on a characterization of the at least one obscurant.

Claims

1. A method of imaging a target, the method comprising:

characterizing at least one obscurant present in an environment;

determining one or more variables;

based on the at least one characterized obscurant, wherein the one or more variables are selected from a group consisting of;

one or more wavelengths corresponding to the at least one obscurant;

a polarization state corresponding to the at least one obscurant; and

a sensor exposure time corresponding to the at least one obscurant; and

adjusting one or more parameters of an imagining system based at least in part on a characterization of the at least one obscurant.

2. The method of claim 1, wherein the at least one obscurant comprises at least one of snow, rain, fog, clouds, smoke, smog, sand, and dust.

3. The method of claim 1, wherein characterizing the at least one obscurant is performed after receiving a user input comprising a selected obscurant.

4. The method of claim 3, further comprising:

accessing a database storing a plurality of parameters corresponding to a plurality of obscurant characterizations, wherein each individual obscurant characterization comprises one or more of at least one wavelength parameter, at least one polarization parameter, and at least one exposure time parameter; and

selecting a selected obscurant characterization corresponding to the selected obscurant.

5. The method of claim 4, wherein, based on the selected obscurant characterization, the method further comprises:

applying a multispectral filter having a selected wavelength parameter associated with the selected obscurant characterization to filter the wavelength received by a sensor;

applying a polarization filter having a selected polarization state associated with the selected obscurant characterization to filter the polarization of light received by the sensor; and

adjusting a sensor exposure time of the sensor in accordance with the selected obscurant characterization.

6. The method of claim 3, wherein the plurality of obscurant characterizations is based at least in part on historical obscurant data.

7. The method of claim 3, wherein characterizing at least one obscurant further comprises receiving a geolocation, a date, a time of day, a temperature, an atmospheric pressure, and a humidity.

8. The method of claim 1, further comprising:

controlling a light source to emit a beam by sweeping the beam across a plurality of wavelengths;

selectively applying a spectral filter of a plurality of spectral filters to the sensor corresponding to the plurality of wavelengths;

detecting, using a sensor, an optical power of returned optical radiation of the beam for individual wavelengths of the plurality of wavelengths of the beam; and

determining a wavelength of returned optical radiation providing an optimal optical power.

9. The method of claim 8, wherein:

the wavelength of returned optical radiation providing an optimal optical power is determined by individual pixels of the sensor; and

individual pixels of the sensor correspond to individual portions of the at least one obscurant such that individual portions of the at least one obscurant are characterized.

10. The method of claim 1, further comprising:

controlling a light source to emit a beam through the obscurant and onto a target by sweeping the beam across a plurality of wavelengths and selectively applying a spectral filter to the sensor corresponding to the plurality of wavelengths;

for each wavelength of the plurality of wavelengths, generating an image of the target;

for each image of the target, generating an image quality metric; and

selecting the wavelength associated with the image having a highest image quality metric as the wavelength parameter.

11. The method of claim 1, further comprising:

selectively applying a spectral filter of a plurality of wavelengths to the sensor;

for each wavelength of the plurality of wavelengths, generating an image of a target;

for each image of the target, generating an image quality metric; and

selecting the wavelength associated with the image having a highest image quality metric as the wavelength parameter.

12. The method of claim 1, further comprising:

controlling a light source to emit a beam by changing a polarization state of the beam;

selectively applying a polarization filter of a plurality of polarization filters to the sensor corresponding to the plurality of polarizations;

detecting an optical power of returned optical radiation of the beam for individual polarization states of a plurality of polarization states; and

determining a polarization state providing an optimal optical power.

13. The method of claim 12, wherein:

the polarization state providing an optimal optical power is determined by individual pixels of the sensor; and

individual pixels of the sensor correspond to individual portions of the at least one obscurant such that individual portions of the at least one obscurant are characterized.

14. The method of claim 13, wherein the polarization state of the beam is selected from a group consisting of:

a circular polarization, a linear polarization, and an elliptical polarization.

15. The method of claim 1, further comprising:

controlling a light source to emit a beam through the obscurant and onto a target by changing a polarization state of the beam across a plurality of polarization states and selectively applying a polarization filter to the sensor corresponding to the plurality of polarization states;

for each polarization state of the plurality of polarization states, generating an image of the target;

for each image of the target, generating an image quality metric; and

selecting the polarization state associated with the image having a highest image quality metric as the polarization parameter.

16. The method of claim 1, further comprising:

selectively applying a polarization filter having a plurality of polarization states to the sensor;

for each polarization state of the plurality of polarization states, generating an image of a target;

for each image of the target, generating an image quality metric; and

selecting the polarization state associated with the image having a highest image quality metric as the polarization parameter.

17. The method of claim 1, further comprising:

controlling a light source to emit a beam;

controlling the sensor to receive returned optical radiation of the beam by sweeping a range of exposure times;

detecting an optical power of returned optical radiation of the beam for an individual exposure time of the plurality of exposure times; and

determining a selected exposure time for one or more regions of interest of a scene providing an optimal optical power.

18. The method of claim 1, further comprising:

controlling a light source to emit a beam;

creating a plurality of images, each image of the plurality of images having a different exposure time;

determining an image quality metric for each image; and

selecting the exposure time associated with the image having a highest image quality metric as an exposure time parameter.

19. The method of claim 1, further comprising:

creating a plurality of images, each image of the plurality of images having a different exposure time;

determining an image quality metric for each image; and

selecting the exposure time associated with the image having a highest image quality metric as an exposure time parameter.

20. The method of claim 1, wherein characterizing at least one obscurant comprises:

controlling a light source to emit a beam by sweeping the beam across a plurality of wavelengths;

detecting, by individual pixels of a sensor, an optical power of returned optical radiation of the beam for individual wavelengths of the plurality of wavelengths of the beam;

determining a wavelength of returned optical radiation providing an optimal optical power among the plurality of wavelengths of the beam;

controlling the light source to emit the beam by sequentially changing a polarization state of the beam;

detecting, by the individual pixels of the sensor, the optical power of returned optical radiation of the beam for individual polarization states of a plurality of polarization states;

determining a polarization state providing an optimal optical power among the plurality of polarization states;

controlling the sensor to receive returned optical radiation by sweeping a range of exposure times;

detecting an optical power of returned optical radiation of the beam for an individual exposure time of the plurality of exposure times; and

determining a selected exposure time for one or more regions of interest of a scene providing an optimal optical power among the plurality of exposure times.

21. The method of claim 1, further comprising controlling a light source to emit an illumination beam, wherein:

the illumination beam has a polarization state corresponding to a polarization parameter of the obscurant; and

the illumination beam has a wavelength corresponding to a wavelength parameter of the obscurant.

22. The method of claim 21, further comprising operating the sensor at an exposure time corresponding to an exposure time parameter of the obscurant.

23. The method of claim 22, further comprising controlling the light source such that the illumination beam is scanned across a target.

24. The method of claim 22, further comprising operating the sensor at a plurality of exposure times for a plurality of regions of interest of a scene.

25. The system of claim 1, wherein:

the at least one obscurant that is present within the environment is characterized by an active characterization process; and

a characterization of the at least one obscurant and environmental data surrounding the characterization of the at least one obscurant are stored in a database as historical characterization data.

26. A method of imaging a target, the method comprising:

actively characterizing at least one obscurant present in an environment by illuminating one of a target and an obscurant using a laser beam and detecting reflected light of the laser beam;

determining, based on the at least one characterized obscurant, one or more of the following;

one or more wavelengths corresponding to the at least one obscurant;

a polarization state corresponding to the at least one obscurant; and

a sensor exposure time corresponding to the at least one obscurant; and

adjusting one or more parameters of an imagining system based at least in part on a characterization of the at least one obscurant.