Laser beam image contrast enhancement

• US 8,629,988 B2
• Filed: 04/20/2009
• Issued: 01/14/2014
• Est. Priority Date: 04/20/2009
• Status: Active Grant

• Current Assignee: Javad GNSS, Inc.
• Original Assignee: Javad GNSS, Inc.
• Inventors: Gribkov, Mikhail
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): BRYANT, REBECCA CAROLE
• Application Number:
  US12/426,798
• Publication Number:
  US 20100265505A1
• Time in Patent Office: 1,730 Days
• Field of Search: 356/369, 356/614, 356/620, 356/622
• US Class Current: 356/622
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/499 using polarisation effects

Abstract

An apparatus and method for providing image contrast enhancement is disclosed. A mobile object is equipped with a laser source, polarization filter, and imaging apparatus. The reflection of the laser source output passes through the filter and is received by the imaging apparatus. If the output of the laser source impinges a metallic marker plate located at a pre-determined location, the filter decreases the intensity level of image components not associated with the reflection of the laser source output. The imaging apparatus uses such filtered image components to determine the position and/or orientation of the mobile object.

Claims

1. A mobile object equipped for position or orientation determination, comprising:

a laser source configured to output a laser beam;

a polarization filter;

an imaging apparatus configured to receive an output of the polarization filter and output an image comprising a plurality of pixels; and

a processor in communication with the imaging apparatus and configured to;

identify a reflection of the laser beam from a marker in the image by performing image scanning to identify a threshold number of contiguous pixels of the plurality of pixels that are at or above a threshold intensity level; and

determine a position or an orientation of the mobile object relative to the marker based upon the identified reflection of the laser beam from the marker.

2. The mobile object of claim 1, wherein the marker is located at a predetermined location, the reflection comprises diffuse reflection, and the marker is a metallic marker.

3. The mobile object of claim 1, wherein the polarization filter comprises a circular polarization filter.

4. The mobile object of claim 1, wherein the polarization filter comprises a linear polarization filter.

5. The mobile object of claim 1, wherein the polarization filter comprises a linear polarization filter and a second polarization filter.

6. The mobile object of claim 1, wherein a main plane of transmission of the polarization filter is substantially parallel to a plane of polarization of the laser beam.

7. The mobile object of claim 1, wherein the threshold intensity level is equal or greater than intensity levels associated with the rest of the image.

17. The mobile object of claim 1 further comprising:

a positioning system configured to determine the position of the mobile object based upon the orientation of the mobile object.

18. The mobile object of claim 1, wherein the positioning system is a global positioning system receiver.

8. A method for determining position or orientation of a mobile unit, comprising:

providing a laser beam from a laser included in the mobile unit;

generating an image comprising a plurality of pixels at an imaging apparatus;

providing a filter in front of the imaging apparatus; and

identifying a reflection of the laser beam from a marker in the image by performing image scanning to identify a threshold number of contiguous pixels of the plurality of pixels that are at or above a threshold intensity level; and

determining a position or an orientation of the mobile unit relative to the marker based upon the identified reflection of the laser beam from the marker.

9. The method of claim 8, wherein the marker is a metallic target at a predetermined location.

10. The method of claim 9, further comprising generating the reflection of the laser beam from the laser beam impinging the metallic target.

11. The method of claim 8, wherein the filter comprises one or more polarization filters.

12. The method of claim 8, wherein providing the filter includes orientating a main plane of transmission of the filter substantially parallel to a plane of polarization of the laser beam.

13. A system for determining a position or orientation of a mobile unit based on laser contrast enhancement, comprising:

a target; and

a mobile unit including;

a laser configured to output a beam,

an imaging apparatus configured to capture images, each captured image comprising a plurality of pixels,

a polarization filter located in front of the imaging apparatus and configured to decrease intensity of incoming light not having a plane of polarization substantially parallel to a main plane of transmission of the polarization filter;

a processor in communication with the imaging apparatus and configured to identify a reflection of the laser beam from the target in the captured images by performing image scanning to identify a threshold number of contiguous pixels in the captured images that are at or above a threshold intensity level; and

a positioning system configured to determine a position of the mobile unit based on the identified reflection of the laser beam from the target.

14. The system of claim 13, wherein the beam impinges the target to generate a diffuse reflection and the diffused reflection is included in an image captured by the imaging apparatus.

15. The system of claim 14, wherein the mobile unit is in a line of sight to the target and oriented for the beam to impinge on the target.

16. The system of claim 13, wherein the positioning system is a global positioning system.