Patent ID: 9605967
Date: 2017-03-28
CPC Classifications: G01C,G08G,G09B

Claim:
1. A tunnel entrance elevation specifying device configured to validate or correct electronic map information, including a computer system having a non-transitory computer-readable storage medium containing programming for tunnel entrance elevation specifying, comprising: an electronic map data storing portion configured to store an electronic map information; a special target entrance selecting portion configured to select a tunnel entrance, which is connected to an elevated road, from the electronic map data storing portion, the tunnel entrance serving as a special target entrance; a special target road link assigning portion configured to assign a road link, which includes the special target entrance, as a special target road link, the road link being retrieved from the electronic map data storing portion; a trusted point identifying portion configured to identify first and second trusted points located on the special target road link, the first and second trusted points having the special target entrance located therebetween; a first elevation calculating portion configured to calculate a first elevation corresponding to coordinates for the special target entrance by performing linear interpolation on elevation values associated with the identified first and second trusted points; a special target entrance elevation specifying portion configured to specify the calculated first elevation as an elevation of the special target entrance; a second elevation acquiring portion configured to acquire a second elevation of the special target entrance by performing linear interpolation using electronic mesh elevation data sets for four points surrounding the special target entrance; a validity determining portion configured to determine that the first elevation is not valid when a difference between the first elevation and the second elevation is equal to or greater than a second threshold value; and a correcting portion configured to correct the first elevation when the validity determining portion determines that the first elevation is not valid or not to correct the first elevation when the validity determining portion determines that the first elevation is valid; wherein the trusted point identifying portion acquires elevations for a predetermined region that includes an arbitrary point on the special target road link; and the trusted point identifying portion identifies a boundary point between a flat part and a slope part on the special target road link as the trusted point.