System for road sign sheeting classification
First Claim
1. A method for determining sheeting type of a reflective sheeting material covering at least a portion of a surface of a road sign comprising:
- using a light source to illuminate at least a portion of the reflective sheeting material covering the road sign as the light source is traversed along the roadway;
collecting a plurality of light intensity measurements reflected from the at least a portion of the reflective sheeting material to generate an as-measured retroreflectivity profile, the light intensity measurements corresponding to exemplary angular displacements of incident light from a reference position; and
determining sheeting type of the reflective sheeting material based on the as-measured retroreflectivity profile.
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Accused Products
Abstract
A system for classifying different types of sheeting materials of road signs depicted in a videostream compares estimated retroreflectivity values against known minimum retroreflectivity values for each of a plurality of colors. Once a road sign has been identified in the videostream, the frames associated with that road sign are analyzed to determine each of a plurality of colors present on the road sign. An estimated retroreflectivity for each of the plurality of colors present on the road sign is then determined. By comparing the estimated retroreflectivity for each of the plurality of colors against known minimum retroreflectivity values for the corresponding color for different types of sheeting materials, an accurate determination of the classification of the sheeting material of the road sign is established. Preferably, certain conditions of gross failure of the sheeting material are filtered out before classification of the sheeting material is determined.
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Citations
19 Claims
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1. A method for determining sheeting type of a reflective sheeting material covering at least a portion of a surface of a road sign comprising:
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using a light source to illuminate at least a portion of the reflective sheeting material covering the road sign as the light source is traversed along the roadway;
collecting a plurality of light intensity measurements reflected from the at least a portion of the reflective sheeting material to generate an as-measured retroreflectivity profile, the light intensity measurements corresponding to exemplary angular displacements of incident light from a reference position; and
determining sheeting type of the reflective sheeting material based on the as-measured retroreflectivity profile. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for determining sheeting type of a reflective sheeting material covering a road sign comprising:
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means for illuminating at least a portion of the reflective sheeting material covering the road sign from a plurality of distances along the roadway;
means for collecting a plurality of light intensity measurements reflected from the at least a portion of the reflective sheeting material;
means for generating an as-measured retroreflectivity profile using the light intensity measurements corresponding to exemplary angular displacements of incident light from a reference position;
means for providing a database of retroreflectivity profiles with each retroreflectivity profile having an associated known sheeting type;
means for comparing the as-measured profile to each retroreflectivity profile from the retroreflectivity profile pool;
means for selecting the retroreflectivity profile that best correlates to the as-measured retroreflectivity profile; and
means for determining sheeting type of the reflective sheeting material based on the known sheeting type associated with the selected retroreflectivity profile. - View Dependent Claims (16, 17)
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18. A system determining sheeting type of a reflective sheeting material covering a road sign comprising:
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at least one light source mounted on a vehicle capable of traversing a roadway and suitable for illuminating at least a portion of the road sign;
at least one light intensity sensor for receiving light reflected from the road sign and computing the intensity of the received light;
a positioning system for determining a location of the vehicle from a stationary frame of reference;
a ranging system for determining a distance of the road sign from the light source and an inclination of a surface of the road sign relative to the light source;
a control system operably connected to the light source, intensity sensor, positioning system and ranging system such that the intensity sensor, ranging system and positioning system record information associated with an area that includes at least one road sign 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 an as-measured retroreflectivity profile having an as-measured shape and comprising the plurality of as-measured retroreflectivity values for the sheeting type of the road sign and comparing the as-measured shape with a characteristic shape of at least one known retroreflectivity profile in a database of known retroreflectivity profiles for each of a plurality of different sheeting types to classify a sheeting material of the road sign as one of the plurality of different sheeting types.
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19. A method for classifying a road sign having sheeting types having at least one color, each sheeting type of a particular color covering at least one non-overlapping area of the road sign, the method comprising the steps of:
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using a light source to illuminate at least a portion of the reflective sheeting material covering the road sign as the light source is traversed along the roadway;
collecting a plurality of light intensity measurements reflected from the at least a portion of the reflective sheeting material to generate an as-measured retroreflectivity profile, 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 sheeting type having a known color;
providing a database of road signs, each road sign categorized according to a set of colors associated with each known sheeting type covering the road sign;
selecting at least one retroreflectivity profile from the retroreflectivity profile pool that best correlates to at least a portion of the as-measured retroreflectivity profile;
determining a set of sheeting types associated with the selected retroreflectivity profiles; and
classifying the road sign according to the set of colors associated with the set of selected sheeting types.
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Specification