Detecting Common Geographic Features in Images Based on Invariant Components

Abstract

Systems, devices, features, and methods for detecting common geographic features in images, such as, for example, to develop a navigation database are disclosed. For example, a method of detecting a common text pattern, such as for a road or path sign, from collected images includes collecting a plurality of images of geographic areas along a road or path. An image of the plurality of images is selected. Components that correspond to an object about the road or path in the selected image are determined. In one embodiment, the determined components are independent or invariant to scale of the object. The determined components are compared to reference components in a data library. If the determined components substantially match the reference components, the object in the selected image is identified to be a common pattern, such as for a standard road or path sign, corresponding to the reference components in the data library.

We claim: 
     
         1 . A non-transitory computer readable medium configured to store a computer program that performs a method of identifying a commonly labeled path sign in an image corresponding to a path, the method comprising:
 identifying a standard path sign in an image of a path;   determining data components that correspond to the standard path sign, the data components being scale-invariant components representing a text pattern of the standard path sign;   storing the data components that correspond to the standard path sign in a navigation library of a map database developer;   selecting another image representing another path;   determining scale-invariant components of the other image; and   comparing the determined scale-invariant components of the other image with the data components stored in the navigation library to determine if the other image includes a path sign substantially similar to the standard path sign.   
     
     
         2 . The non-transitory computer readable medium of  claim 1 , the method further comprising:
 generating a modification for a navigational database based on the comparison.   
     
     
         3 . The non-transitory computer readable medium of  claim 1 , wherein the standard path sign comprises a speed limit sign or a stop sign. 
     
     
         4 . The non-transitory computer readable medium of  claim 1 , wherein determining the scale-invariant components of the standard path sign comprises:
 determining amplitude extrema in regions of a difference image, the difference image comprising an image generated from a difference between the image of the path and a blurred image of the path.   
     
     
         5 . The non-transitory computer readable medium of  claim 1 , wherein the data components are substantially invariant to rotation. 
     
     
         6 . The non-transitory computer readable medium of  claim 1 , wherein the data components are substantially invariant to illumination. 
     
     
         7 . The non-transitory computer readable medium of  claim 1 , further comprising:
 if the determined scale-invariant components substantially match the data components in the navigation library, providing identification of the selected other image to the map database developer.   
     
     
         8 . The non-transitory computer readable medium of  claim 7 , wherein providing the identification includes providing a text file. 
     
     
         9 . The non-transitory computer readable medium of  claim 8 , wherein the text file includes location information of where the selected other image was taken. 
     
     
         10 . A method comprising:
 identifying a path sign in an image of a path;   determining data components that correspond to the standard path sign, the data components being scale-invariant components representing a pattern of the standard path sign;   performing a comparison of the data components that correspond to the standard path sign to a navigation library to determine if the other image includes the path sign; and   generating a modification for a navigational database based on the comparison.   
     
     
         11 . The method of  claim 10 , further comprising:
 identifying a standard path sign in an image;   determining data components that correspond to the standard path sign, the data components being scale-invariant components representing a pattern of the standard path sign; and   storing the data components that correspond to the standard path sign in a navigation library.   
     
     
         12 . The method of  claim 10 , wherein the path sign comprises a speed limit sign or a stop sign. 
     
     
         13 . The method of  claim 10 , wherein determining the scale-invariant components of the path sign comprises:
 determining amplitude extrema in regions of a difference image, the difference image comprising an image generated from a difference between the image of the path and a blurred image of the path.   
     
     
         14 . The method of  claim 10 , wherein the data components are substantially invariant to rotation. 
     
     
         15 . The method of  claim 10 , wherein the data components are substantially invariant to illumination. 
     
     
         16 . The method of  claim 1 , wherein the modification to the navigational database includes a speed limit assigned to a road segment. 
     
     
         17 . The method of  claim 1 , wherein the modification to the navigational database includes a road marking or a street name. 
     
     
         18 . The method of  claim 1 , wherein the modification to the navigational database includes turn restrictions at intersections. 
     
     
         19 . The method of  claim 1 , wherein the modification to the navigational database includes a point of interest name. 
     
     
         20 . An apparatus comprising:
 at least one processor; and   at least one memory including computer program code for one or more programs; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least perform:   identifying a standard path sign in an image of a path;   determining data components that correspond to the standard path sign, the data components being scale-invariant components representing a pattern of the standard path sign;   storing the data components that correspond to the standard path sign in a navigation library of a map database developer;   selecting another image representing another path;   determining scale-invariant components of the other image;   comparing the determined scale-invariant components of the other image with the data components stored in the navigation library to determine if the other image matches the standard path sign.