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

• US 20070216904A1
• Filed: 02/05/2007
• Published: 09/20/2007
• Est. Priority Date: 06/07/2001
• Status: Active Grant

• Current Assignee: AMAC NORTH AMERICA, LLC
• Original Assignee: Facet Technology Corp.
• Inventors: Laumeyer, Robert, Retterath, James
• Granted Patent: US 7,411,681 B2
• Time in Patent Office: Days
• 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. A method of automated determination of retroreflectivity values for reflective surfaces comprising:

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

collecting a plurality of light intensity measurements 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 measurement associated with one of the at least one reflective surfaces; and

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

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

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

collecting a plurality of light intensity measurements 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 measurement associated with one of the at least one reflective surfaces; and

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