System for automated determination of retroreflectivity of road signs and other reflective objects

• US 7,173,707 B2
• Filed: 05/03/2006
• Issued: 02/06/2007
• Est. Priority Date: 06/07/2001
• Status: Expired due to Term

• Current Assignee: AMAC NORTH AMERICA, LLC
• Original Assignee: Facet Technology Corp.
• Inventors: Retterath, James E., Laumeyer, Robert A.
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Assistant Examiner(s): Akanbi, Isiaka O.
• Application Number:
  US11/381,503
• Publication Number:
  US 20060262312A1
• Time in Patent Office: 279 Days
• Field of Search: 356/121, 356445-448, 356/508, 356/237.3, 356/455, 359/529, 359/627
• US Class Current: 356/445
• CPC Class Codes: G01N 2021/551 Retroreflectance
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G08G 1/0962 having an indicator mounted inside the vehicle, e.g. giving voice messages
• CPC Class Codes: G08G 1/096716 where the received information does not generate an automatic action on the vehicle control
• CPC Class Codes: G08G 1/096758 where no selection takes place on the transmitted or the received information
• CPC Class Codes: G08G 1/096775 where the origin of the information is a central station
• CPC Class Codes: G08G 1/096783 where the origin of the information is a roadside individual element
• CPC Class Codes: G08G 1/096791 where the origin of the information is another vehicle

Abstract

A system for the automated 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 strobing 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 for displaying and manipulating retroreflectivity data for a reflective surface disposed along a roadway comprising:

determining a plurality of retroreflectivity values for the reflective surface;

generating a three-dimensional representation of retroreflectivity values of the reflective surface; and

displaying the three-dimensional representation of retroreflectivity values.

2. The method of claim 1, further comprising:

generating a simulated vehicle light source and a vehicle operator/observer pair; and

for different locations of the simulated vehicle light source and said vehicle operator/observer pair, generating a simulated vehicle operator/observer observation angle and a simulated view of the vehicle pathway which includes the reflective surface.

3. The method of claim 2, further comprising:

simulating a changing magnitude of ambient lighting from a first value to a second value.

4. The method of claim 2, further wherein the three-dimensional representation of retroreflectivity values is displayed as an overlay on a depiction of the roadway.

5. The method of claim 4, further comprising:

simulating a change of at least one characteristic of the depiction of the roadway; and

determining and simulating a corresponding change in the three-dimensional representation of retroreflectivity values.

6. The method of claim 5, wherein the characteristic is selected from one or more of the set consisting of:

a location of the reflective surface, a sheeting type of the reflective surface, a location of a non-reflective surface, a location of an illuminated sign, an illumination value of an illuminated sign, an observation angle between a vehicle operator and a source of vehicle illumination, a form of precipitation between the vehicle and the reflective surface, a form of debris disposed upon the reflective surface, an angle of the reflective surface and an angle of an illuminated sign.

7. The method of claim 1, wherein generating the simulated vehicle operator/observer observation angle and the simulated view of the vehicle pathway occurs with a source of illumination selected from the set consisting of:

a high beam vehicle lighting condition, a low beam vehicle lighting condition, light emitting diodes or an auxiliary beam vehicle lighting condition.

8. The method of claim 1, further comprising:

generating a new three-dimensional depiction of the reflective surface according to a predictive aging model which includes a gradual degradation of the reflective surface over time; and

,

representing the reflective surface as if the reflective surface exhibited such a gradual degradation in the three-dimensional depiction.

9. The method of claim 8, further comprising:

associating a sheeting type to the reflective surface; and

generating an additional three-dimensional depiction of the reflective surface based in part on a predicted degradation of the associated sheeting type.

10. The method of claim 1, wherein the reflective surfaces are road signs disposed along a roadway and the step of determining the retroreflectivity values for the reflective surfaces comprises measuring at least one light intensity value of a light source reflected off each road sign and determining a retroreflectivity value in response to the light intensity value.

11. The method of claim 1, wherein at least a portion of the reflective surfaces are road signs planned to be deployed along a roadway and the step of determining the retroreflectivity values for the reflective surfaces comprises inputting retroreflectivity values for each planned road sign based on a sheeting type of the planned road sign.

12. A method for simulating a virtual drive-through that includes at least one reflective surface disposed along a roadway comprising:

determining a plurality of retroreflectivity values for each reflective surface; and

simulating a virtual drive-through along the roadway using the plurality of retroreflectivity values to simulate reflections from each reflective surface disposed along the roadway during the virtual drive-through.

13. The method of claim 12, further comprising:

simulating a change of at least one characteristic of the depiction of the roadway; and

determining and simulating a corresponding change in the reflections from each reflective surface.

14. The method of claim 12, wherein a vehicle having a light source and observer pair is simulated in the virtual drive.

15. The method of claim 14, further comprising:

simulating a change of at least one characteristic of the vehicle or light source and observer pair; and

determining and simulating a corresponding change in the reflections from each reflective surface.

16. The method of claim 12, wherein the reflective surfaces are road signs disposed along the roadway and the step of determining the retroreflectivity values for the reflective surfaces comprises measuring at least one light intensity value of a light source reflected off each road sign and determining a retroreflectivity value in response to the light intensity value.

17. The method of claim 12, wherein at least a portion of the reflective surfaces are road signs planned to be deployed along the roadway and the step of determining the retroreflectivity values for the reflective surfaces comprises inputting retroreflectivity values for each planned road sign based on a sheeting type of the planned road sign.