Abstract: An approach is provided for generating a minimum overlapping alternative path. The approach involves receiving a constraint parameter for traversing a path between a first location and a second location. The approach also involves determining a critical portion of the path that is to be traveled to satisfy the constraint parameter, and designating a remaining portion of the path that is not the critical portion as a non-critical portion. The approach further involves calculating one or more candidate minimum overlapping alternative paths for the non-critical portion of the path. The approach further involves generating the minimum overlapping alternative path between the first location and the second location by combining the critical portion of the path with a selected one of the one or more candidate minimum overlapping alternative paths that satisfies the constraint parameter.

Abstract: An approach is provided for filtering device location points in a sampled trajectory while maintaining path reconstructability. The approach involves determining a first location point in the sampled trajectory that is an unfiltered location point. The sampled trajectory includes device location points sampled by a device traversing a road network. The approach also involves determining a fastest alternative path from the first location point to a second location point. The approach further involves calculating a sampling time difference between a time at which the first location point was sampled and another time at which the second location point was sampled. The approach further involves designating the second location point as a next unfiltered location point when the sampling time difference is within a threshold value of a free-flow travel time calculated for the fastest alternative path. Otherwise, the second location point is designated as a filtered location point.

Abstract: An approach is provided for generating a minimum overlapping alternative path. The approach involves receiving a constraint parameter for traversing a path between a first location and a second location. The approach also involves determining a critical portion of the path that is to be traveled to satisfy the constraint parameter, and designating a remaining portion of the path that is not the critical portion as a non-critical portion. The approach further involves calculating one or more candidate minimum overlapping alternative paths for the non-critical portion of the path. The approach further involves generating the minimum overlapping alternative path between the first location and the second location by combining the critical portion of the path with a selected one of the one or more candidate minimum overlapping alternative paths that satisfies the constraint parameter.

Abstract: An approach is provided for filtering device location points in a sampled trajectory while maintaining path reconstructability. The approach involves determining a first location point in the sampled trajectory that is an unfiltered location point. The sampled trajectory includes device location points sampled by a device traversing a road network. The approach also involves determining a fastest alternative path from the first location point to a second location point. The approach further involves calculating a sampling time difference between a time at which the first location point was sampled and another time at which the second location point was sampled. The approach further involves designating the second location point as a next unfiltered location point when the sampling time difference is within a threshold value of a free-flow travel time calculated for the fastest alternative path. Otherwise, the second location point is designated as a filtered location point.