Vehicle navigation and map quality

The impact of map errors on VNIS systems as function of error type may not be well understood. Errors of two kinds are considered: errors of geometry which are correctable within VNIS systems by map-matching hardware, software, and algorithms; and errors of topology which may not be easily correctable by common hardware or software strategies. Comparison of two vendors' digital maps of State College, Pennsylvania with each other illustrates both kinds of errors, and also points out that the impact of errors may depend greatly on the context of local traffic patterns, which themselves may vary in non-predictable ways. There are thus both functional and dynamic components of map data quality.