[aprssig] Re: FindU Maps Quirky

[Stephen H. Smith]

Ray McKnight wrote on 2/6/2005, 11:21 PM:

 > Steve, if you zoom in to street level on my FindU map,
 >
 > You’ll notice that although I am actually located about 1 mile
 >
 > From the water, a significant amount of the streets in my neighborhood
 >
 > Are depicted as being in Puget Sound, yeah, in the water!
 >
 >
 >
 > Gee, looking at Seattle a little closer now, there seems to be
 > thousands of streets
 >
 > Depicted as being in the drink.  Any hope of correcting this??
 >
 > Does this link show what I’m talking about:

This has nothing to do with findu!

Street information, outlines of cities, counties, states, and of bodies 
of water are typically stored in separate databases and then drawn as 
multiple layers on top of each other.   The map you see is assembled 
on-the-fly from multple databases at aprsworld.com at findu's request. 
In turn,  the various layers of data come from different public-domain 
sources and have varying degrees of accuracy, especially when data 
referenced to one datum is converted to another.

The water features database which contains coastlines, lakes and rivers 
seems to have major errors in it.  I see the same problems here in 
Southern California where most of Santa Monica, LAX and parts of the San 
Diego Freeway (I-405) are "underwater".  [And, please, no smart cracks 
about them really being that way after the recent January floods!]


The real issue is how much do you want to <<PAY>> to have access to 
commercially enhanced and corrected data versus using free public domain 
  data???


Note:  You can see some similar errors in Precision Mapping 7.0   Zoom 
in on the channel between the eastern tip of Michigan's Upper Peninsula 
  and Sault Ste Marie, Ontario.   You will see Canadian roads, including 
Ontario Route 548 apparently in the water, along with a bunch of small 
towns.  Somehow the outline of an entire island (St Joseph's) slipped 
through the cracks of the Canadian database provided to Undertow 
software by GDT (Geographic Data Technology).




Stephen H. Smith                wa8lmf (at) aol.com

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