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[aprssig] Re: APRSPoint and other map sources

Stephen H. Smith WA8LMF2 at aol.com
Thu Dec 2 06:54:59 UTC 2004


Matt Werner wrote on 12/1/2004, 8:32 PM:

 > I have 2003 street
 > level data for any part of the US, simply by downloading the map and
 > placing it in the correct directory.
 >
 > I don't personally find the maps to be ugly either...  It shows a line
 > for a road - only so many ways to represent a road...
 >
 > Just one user's point of view anyway..

I fully agree with the original poster's comment about "uglyness" of 
maps.  The raw Tiger file database, as presented in most applications 
that use it, fails to distinguish (by using different line weights 
and/or colors) between dirt roads, minor side streets, major urban 
streets, or secondary highways. About the only roads that look different 
are the Interstate highways.  Additionally, limited-access freeway-type 
roads that happen to have local or state numbers (instead of federal I- 
numbers) are often rendered looking like local streets instead.


Furthermore, for mobile non-Internet-connected operation, the entire raw 
Tiger database, as downloaded, is enormously bulky compared to the 
commercially-enhanced databases that come with Delorme Street Atlas, 
MapPoint, Streets&Trips, Precision Mapping, etc.  These programs encode 
every street and road segment in the US, including street-address 
indexing, into a total database of less than 1 GB.

For mobile applications, don't even mention the various bitmap 
image-oriented formats such as Terraserver images, USGS Topo map images, 
GeoTIFFs, etc.  Just too incredibly bulky for large areas compared to 
compressed vector formats.

By the way, both MapPoint 2004   (used by APRSpoint and UI-View's add-in 
UI-Point)   and Precision Mapping 6.0   (used directly by UI-View)   use 
the SAME commercially enhanced and cleaned-up Tiger database sold by GDT 
(Geographic Data Technology) to various map publishers.
      You will see almost exactly the same errors, missing streets, etc 
  (as well as accurate rendition of freeway exit and transition ramps, 
interior roads in major airports and industrial parks, etc)  in both 
products because they are based on the same data source. Only the 
presentation (line weights, colors, etc.) are different.
      The points of interest (parks, museums, airports, schools, etc.) 
called out in the two products WILL be different since this information 
is purchased from completely different sources and is overlaid on the 
background map.


Stephen H. Smith                wa8lmf (at) aol.com

Home Page:                      http://wa8lmf.com

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