I wonder..how come one CD-ROM such as Delorme or Microsoft Streets has street level detail of every town in the USA yet on auto systems, (even on Alpine’s DVD which I now have) only one or two major metro areas per state has street level detail, the rest of the State having only State map level detail? Perhaps on auto systems there has to be so much detail on each street segment, that they are progressively mapping the entire USA. Maybe by the year 2002 every street in the USA will be on such systems as Alpine and Magellan and downloadable on to Garmin such as its III+. Anyone know ?
I can’t give you a date but what you have stated is definately true. There are several sources of data for US maps and depending on which source you choose you may find more or less coverage. Many vendors began with the tiger database which gives complete US coverage but the accuracy is spotty. Vendors that began that way may have improved their maps in certain areas based on research and customer feedback. Others are using their own sources and may not be complete for the whole country but are generally more accurate for the areas that are covered. In addition many of the features of the maping units require data that is not normally a part of the tiger database. This information needs to be present to support such things as next intersection information, street address searching, etc.
Currently the etak database is the most complete for the USA. This is what Rand McNally uses for their maps and what Garmin uses for metroguide maps. It is also the source of the online maps used in mapsonus. However the underlying roots of etak is still tiger so some parts of the country are no more accuarate than the old tiger stuff. Etak is upgrading this data as resources permit but they are also getting the Europe database built so this effort is not as fast as some would like.
The maps your unit uses are not etak based but come from navtech I believe. You can check http://www.navtech.com/database/database.html for information on coverage and detail for this company.
All of the expensive “built in” automobile navigation systems <that I know of use NavTech map data. They do this because the NavTech database has various information (one way streets, expressway sign information, route numbering, full details of complex intersections, etc) which is required for good automatic directions. Etak info is very good, but nearly as complete.
Unfortunately, NavTech information covers only the 50+ major metro areas in the USA and coverage outside these metro areas is approximately like the Garmin/Lowrance base map detail. Also, the automatic navigation outside the full coverage areas can be difficult to set up depending on the particular automobile navigation program capabilities.
I am told that NavTech will not have “full USA map coverage to the residential street level” for another 5 or 6 years.
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