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[aprssig] Re: TIGER maps what-s the problem?

Robert Bruninga bruninga at usna.edu
Fri Jun 16 02:03:23 UTC 2006


>> If the guy writing the software can't confirm the map data, 
>> why is he using the most misleading possible icon, a pinpoint 
>> or speck, to (mis)represent that data?
>
> Big circle, little circle, pinpoint or speck, it makes no difference 
>in the least.  The guy writing the software has zero, none, zip, 
>nada, information about accuracy or lack thereof,

I disagree.  Each different maping system has to be understood
by the code writer inorder to draw it on the PC.  Therefore he
should have an idea about the map accuracy and should not
let the indicated position be shown as more precise than the
map data (or the APRS amiguity).    In the absence of anything
else, at least he should not allow a zoom so great that the
displayed symbol or ICON is smaller than the 60' accuracy
of standard APRS (unless the compressed format or !DAO! format
is used.

>  Making a big fuzzy circle would be more bogus than
> making a pinpoint.

Not if the pinpoint is smaller than the known errors in the map
or in the transmitted ambiguity of the sender.  It missleads the
viewer and this violates the integrity of APRS.

Even if a BIT map is used.  The author clearly can compute the
"size" of the map, and can compute at what zoom it is inappropriate
to display a position as a pin-point.

de WB4APR, BOb







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