SYSTEM FOR THE DETERMINATION OF RETROREFLECTIVITY OF ROAD SIGNS AND OTHER REFLECTIVE OBJECTS

• US 20130271613A1
• Filed: 02/28/2013
• Published: 10/17/2013
• Est. Priority Date: 08/12/2000
• Status: Active Grant

• Current Assignee: Dbi/cidaut Technologies, LLC
• Original Assignee: Facet Technology Corp.
• Inventors: Retterath, Jamie E., Laumeyer, Robert A.
• Granted Patent: US 9,989,456 B2
• Time in Patent Office: Days
• US Class Current: 348/169
• CPC Class Codes: G01N 21/251 Colorimeters; Construction thereof
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 21/84 Systems specially adapted for particular applications
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 2201/102 Video camera
• CPC Class Codes: G01N 2201/12 Circuits of general importance; Signal processing
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle
• CPC Class Codes: G06V 20/582 of traffic signs
• CPC Class Codes: G08G 1/096758 where no selection takes place on the transmitted or the received information
• CPC Class Codes: G08G 1/096783 where the origin of the information is a roadside individual element

Abstract

A system for the determination of retroreflectivity values for reflective surfaces disposed along a roadway repeatedly illuminates an area along the roadway that includes at least one reflective surface using a light source. Multiple light intensity values are measured over a field of view which includes at least a portion of the area illuminated by the light source. A computer processing system is used to identifying a portion of the light intensity values associated with a reflective surface and analyze the portion of the light intensity values to determine at least one retroreflectivity value for that reflective surface.

Claims

1. A method of automated determination of retroreflectivity values for reflective surfaces disposed along a roadway comprising:

activating a light source as the light source is traversed along the roadway to illuminate an area that includes at least one reflective surface;

determining a plurality of light intensity values with at least one intensity sensor directed to cover a field of view which includes at least a portion of the area illuminated by the light source; and

using a computer processing system to;

identify a portion of at least one light intensity value associated with one of the at least one reflective surfaces; and

analyze the portion of the at least one light intensity value to determine at least one retroreflectivity value for that reflective surface.

2. The method of claim 1, wherein determining a plurality of light intensity values comprises measuring luminance.

3. The method of claim 1, wherein determining a plurality of light intensity values comprises measuring light intensity.

4. A method of automated determination of retroreflectivity values for reflective surfaces disposed along a roadway comprising:

activating a light source as the light source is traversed along the roadway to illuminate an area that includes at least one reflective surface;

determining a plurality of light intensity values with at least one intensity sensor without targeting a particular reflective surface; and

using a computer processing system to analyze the light intensity values associated with one of the at least one reflective surfaces to determine at least one retroreflectivity value for that reflective surface.

5. The method of claim 4, wherein determining a plurality of light intensity values comprises measuring luminance.

6. The method of claim 4, wherein determining a plurality of light intensity values comprises measuring light intensity.

7. A system for acquiring information to assess reflective surfaces disposed along a roadway comprising:

a vehicle having;

at least light source;

at least one light sensor; and

a control system operably connected to the light source and light sensor such that the light sensor records information associated with an area that includes at least one reflective surface as the vehicle traverses along the roadway in response to repeated illumination of the area by the light source; and

a computer processing system that utilizes the recorded information to determine at least one retroreflectivity value for the at least one reflective surface.

8. The system of claim 7, wherein the light sensor records luminance.

9. The system of claim 7, wherein the light sensor records light intensity.

10. A system for automated determination of retroreflectivity values for reflective surfaces disposed along a roadway comprising:

means for repeatedly illuminating an area that includes at least one reflective surface;

means for repeatedly determining light intensity values over a field of view which includes at least a portion of the area illuminated by the light source; and

at least one computer processing system,

including means for identifying a portion of the light intensity values associated with one of the at least one reflective surfaces;

means for analyzing the portion of the light intensity values to determine at least one retroreflectivity value for that reflective surface;

means for recording images of the area; and

means for generating locational information, wherein the means for analyzing utilizes the images and the locational information as part of determining the at least retroreflectivity value for that reflective surface.

11. The system of claim 10, wherein determining light intensity values comprises measuring luminance.

12. The system of claim 10, wherein determining light intensity values comprises measuring light intensity.

13. A method of automated determination of retroreflectivity values for reflective surfaces disposed along a roadway comprising:

illuminating an area along the roadway that includes at least one reflective surface with a light source without targeting the at least one reflective surface with the light source;

determining light intensity values over a field of view which includes at least a portion of the area illuminated by the light source; and

using a computer processing system to;

identify a portion of the light intensity values associated with one of the at least one reflective surfaces; and

analyze the portion of the light intensity values to determine at least one retroreflectivity value for that reflective surface.

14. The method of claim 13, wherein determining light intensity values comprises measuring luminance.

15. The method of claim 13, wherein determining light intensity values comprises measuring light intensity.

16. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

activating a light source to illuminate an area that includes at least one reflective surface without targeting the light source on a particular reflective surface;

determining a plurality of light intensity values with at least one intensity sensor directed to cover a field of view which includes at least a portion of the area illuminated by the light source;

using a computer processing system to;

identify a portion of at least one light intensity value associated with one of the at least one reflective surfaces; and

analyze the portion of the at least one light intensity value to determine at least one retroreflectivity value for that reflective surface;

creating a characterization profile for the light source, the characterization profile including an array of known luminance values of reflections of the light source; and

utilizing the characterization profile for the light source as part of determining the at least one retroreflectivity value for that reflective surface.

17. The method of claim 16, wherein determining a plurality of light intensity values comprises measuring luminance.

18. The method of claim 16, wherein determining a plurality of light intensity values comprises measuring light intensity.

19. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

activating a light source to illuminate an area that includes at least one reflective surface without targeting the light source on a particular reflective surface;

determining a plurality of light intensity values with at least one intensity sensor directed to cover a field of view which includes at least a portion of the area illuminated by the light source;

using a computer processing system to;

identify a portion of at least one light intensity value associated with one of the at least one reflective surfaces; and

analyze the portion of the at least one light intensity value to determine at least one retroreflectivity value for that reflective surface;

creating a characterization profile for the intensity sensor, the characterization profile including an array of intensity values of reflections measured for a known light source; and

utilizing the characterization profile for the intensity sensor as part of determining the at least one retroreflectivity value for that reflective surface.

20. The method of claim 19, wherein determining a plurality of light intensity values comprises measuring luminance.

21. The method of claim 19, wherein determining a plurality of light intensity values comprises measuring light intensity.

22. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

activating a light source to illuminate an area that includes at least one reflective surface without targeting the light source on a particular reflective surface;

determining a plurality of light intensity values with at least one intensity sensor directed to cover a field of view which includes at least a portion of the area illuminated by the light source;

using a computer processing system to;

identify a portion of at least one light intensity value associated with one of the at least one reflective surfaces; and

analyze the portion of the at least one light intensity value to determine at least one retroreflectivity value for that reflective surface;

wherein each light intensity value comprises a frame of pixel intensity values and a plurality of reflective surfaces are present in at least one of the light intensity values.

23. The method of claim 22, wherein determining a plurality of light intensity values comprises measuring luminance.

24. The method of claim 22, wherein determining a plurality of light intensity values comprises measuring light intensity.

25. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

activating a light source to illuminate an area that includes at least one reflective surface without targeting the light source on a particular reflective surface;

determining a plurality of light intensity values with at least one intensity sensor directed to cover a field of view which includes at least a portion of the area illuminated by the light source;

using a computer processing system to;

identify a portion of at least one light intensity value associated with one of the at least one reflective surfaces; and

analyze the portion of the at least one light intensity value to determine at least one retroreflectivity value for that reflective surface;

wherein the step of activating the light source is synchronized to the step of determining the plurality of light intensity values.

26. The method of claim 25, wherein determining a plurality of light intensity values comprises measuring luminance.

27. The method of claim 25, wherein determining a plurality of light intensity values comprises measuring light intensity.

28. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

creating a characterization profile for a light source, the characterization profile including an array of known luminance values associated with reflections of the light source;

creating a characterization profile for an intensity sensor, the characterization profile including an array of intensity values measured for reflections of a known light source; and

using the light source to illuminate an area that includes at least one reflective surface;

determining a plurality of light intensity values with at least one intensity sensor without targeting a particular reflective surface;

collecting a plurality of images with at least one camera directed to cover a field of view which includes at least a portion of the area illuminated by the light source;

using a computer processing system to determine at least one retroreflectivity value for one of the at least one reflective surfaces that reflective surface, including;

identifying a portion of at least one light intensity value associated with one of the at least one reflective surfaces;

utilizing the characterization profile of the light source and the characterization profile for the intensity sensor to determine a luminance value associated with the portion of that light intensity value associated with that reflective surface based on the at least one color associated with that reflective surface; and

converting the luminance value to a retroreflectivity value.

29. The method of claim 28, wherein determining a plurality of light intensity values comprises measuring luminance.

30. The method of claim 28, wherein determining a plurality of light intensity values comprises measuring light intensity.

31. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

activating a light source to illuminate an area that includes at least one reflective surface without targeting the light source on a particular reflective surface;

determining a plurality of light intensity values with at least one intensity sensor directed to cover a field of view which includes at least a portion of the area illuminated by the light source; and

using a computer processing system to;

identify a portion of at least one light intensity value associated with one of the at least one reflective surfaces; and

analyze the portion of the at least one light intensity value to determine at least one retroreflectivity value for that reflective surface.

32. The method of claim 31, wherein determining a plurality of light intensity values comprises measuring luminance.

33. The method of claim 31, wherein determining a plurality of light intensity values comprises measuring light intensity.