Patent attributes
A method of obtaining data for a geographic database is disclosed. Data indicating a plurality of locations along roads including data indicating altitudes at the plurality of locations is provided. Road grade values for a plurality of subsections of the road are computed; each of the subsections is a portion of the road between two of the locations. A plurality of temporary change points are identified as joining two adjacent subsections having road grade values that differ by a value greater than a predetermined amount. Road grade values for each part of the road between adjacent temporary change points are computed. Consecutive parts of the road having road grade values that falls within a predetermined range are grouped into at least one constant road grade section. The geographic database stores data that define the constant road grade section.
