System and assessment of reflective objects along a roadway

• US 9,335,255 B2
• Filed: 10/13/2014
• Issued: 05/10/2016
• Est. Priority Date: 08/12/2000
• Status: Expired due to Term

• Current Assignee: Mandli Communications, Inc.
• Original Assignee: Facet Technology Corp.
• Inventors: Laumeyer, Robert A., Retterath, James E.
• Primary Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US14/512,735
• Publication Number:
  US 20150153271A1
• Time in Patent Office: 575 Days
• US Class Current: 1/1
• 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 assessment of 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 assessment for that reflective surface.

Claims

1. An automated method for classifying a reflective road marker having at least one color comprising:

using a light source to illuminate at least a portion of the reflective road marker as the light source is traversed along a roadway;

collecting a plurality of light intensity measurements reflected from the at least a portion of the reflective road marker, the light intensity measurements corresponding to exemplary angular displacements of incident light from a reference position;

providing a database of retroreflectivity profiles, each retroreflectivity profile having an associated known road marker type having a known color;

and

using a computer processing system configured to;

generate an as-measured retroreflectivity profile based on the plurality of light intensity measurements;

select at least one retroreflectivity profile from the database of retroreflectivity profiles that correlates to at least a portion of the as-measured retroreflectivity profile;

determine a road marker type from a set of road markers that is associated with the selected at least one retroreflectivity profile; and

classify the road marker according to the color associated with the determined road marker type.

2. The automated method of claim 1, wherein the as-measured retroreflectivity profile is a curve of retroreflectivity values calculated from the plurality of light intensity measurements plotted as a function of the exemplary angular displacements of incident light from the reference position.

3. The automated method of claim 2, wherein each of the exemplary angular displacements of incident light comprises an observation angle corresponding to one of a plurality of distances of the light source from the road marker.

4. The automated method of claim 3, further comprising dynamically generating a new retroreflectivity profile based on a change in the observation angle.

5. The automated method of claim 2, wherein each of the exemplary angular displacements comprises an entrance angle corresponding to one of a plurality of distances of the road sign from the road marker.

6. The automated method of claim 1, further comprising determining a lateral distance between the light source and the illuminated portion of the reflective road marker.

7. The automated method of claim 1, wherein the retroreflectivity profile is a characteristic curve including a plurality of known retroreflectivity values.

8. The automated method of claim 1, wherein each of the plurality of light intensity measurements comprises an array of discrete pixel intensity values.

9. The automated method of claim 1, wherein the step of using the computer processing to determine the road marker type:

calculates a degree of correlation between the as-measured retroreflectivity profile and the selected at least one retroreflectivity profile;

selects a type associated with the selected at least one retroreflectivity profile if the degree of correlation lies between an acceptable range of predefined values; and

identifies the road marker as exhibiting a failure if the degree of correlation lies outside the acceptable range of predefined values.

10. The automated method of claim 1, further comprising providing a database of road markers that includes pavement markings, each pavement marking categorized according to a set of colors for the pavement markings that includes yellow, green, red and white.

11. The automated method of claim 10, wherein each color of the set of colors for the pavement markings is associated with a known retroreflectivity value.

16. The automated method of claim 1, further comprising determining a lateral distance between the light source and the illuminated portion of the reflective road marker.

12. An automated method of assessing reflective surfaces disposed along a roadway comprising:

activating a light source as the light source is traversed along a roadway to illuminate an area that includes at least one reflective surface on a road marker, the road marker having a reflective characteristic;

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 configured to;

identify a portion of at least one light intensity value of the plurality of light intensity values associated with one of the at least one reflective surface of the road marker; and

analyze the portion of the at least one light intensity value of the plurality of light intensity values to determine an assessment for the reflective characteristic of the road marker.

13. The automated method of claim 12, wherein activating a light source comprises synchronizing activation of a plurality of light sources to optimize light intensity reflected from the road marker.

14. The automated method of claim 12, wherein activating a light source comprises activating a single light source.

15. The automated method of claim 12, further comprising determining a luminance value utilizing the plurality of light intensity values and a characterization profile of the at least one light intensity sensor.

17. An automated system for assessing reflective surfaces disposed along a roadway comprising:

a light source that is traversed along a roadway to illuminate an area that includes at least one reflective surface on a road marker, the road marker having a reflective characteristic;

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

a computer processing system configured to;

identify a portion of at least one light intensity value of the plurality of light intensity values associated with one of the at least one reflective surface of the road marker; and

analyze the portion of the at least one light intensity value of the plurality of light intensity values to determine an assessment for the reflective characteristic of the road marker.

18. The automated system of claim 17, wherein the computer processing system further comprises a color identification subsystem, the color identification subsystem configured to associate at least one color with the reflective characteristic of the road marker.

19. The automated system of claim 18, wherein the at least one color is selected from a set of colors consisting of yellow, green, red and white.

20. The automated system of claim 17, wherein the light source comprises a laser scanning device.

21. The automated system of claim 17, wherein the light source comprises a vehicle headlight lamp.

22. The automated system of claim 21, wherein the vehicle headlight lamp is selected from a group consisting of a light emitting diode, a xenon lamp, a halogen lamp, a fluorescent lamp, and an incandescent lamp.

23. The automated system of claim 17, wherein the means for determining a plurality of light intensity values comprises a light sensor.