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

Wes Johnston wes at kd4rdb.com
Tue Jun 13 15:59:14 UTC 2006

Actually, the 60' limit of a standard aprs position is killing me with the 
rino radios.  It's very difficult to explain to the layperson looking at a 
photo of an event why all there is only one icon showing near the trailer 
we're using.  The most confusing it seems is when the letters overlay from 
the name of the object.  For example, the objects STIDOM  and BLANKENSHIP 
over lay and become STIDOMNSHIP.  To the non-layperson it's difficult to 
visually local my resources on the map when they are all in a stack right on 
top of each other.  We had 4 people standing at a checkpoint and it looked 
like one.  I had to use the 'find station' option to center that stack on my 
screen, then just accept the person I was interested in was in that pile. 
Of course, just as aggrivating was seeing the rino program catch a position 
from a user and plot him off the viewable area of my map... I spent over a 
minute looking before it dawned on me to zoom out.


----- Original Message ----- 
From: "Curt, WE7U" <archer at eskimo.com>
To: <russo at bogodyn.org>; "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Sent: Tuesday, June 13, 2006 11:32 AM
Subject: Re: [aprssig] Re: TIGER maps what-s the problem?

> On Tue, 13 Jun 2006, Tom Russo wrote:
>> And for regular uncompressed posits, there's something like a 60 foot
>> resolution just because of the limits of the transmitted data.  If zoomed 
>> in
>> to the point that the icon/symbol/pinprick is substantially smaller than 
>> 60
>> feet on the map, it would be reasonable to display a 60 foot circle or
>> rectangle instead, even for a posit with no deliberate ambiguity.  A 
>> similar
>> argument can be made for compressed posits with their extra digit or so 
>> of
>> precision, and !DAO! posits. (FWIW, Xastir is as guilty as the next 
>> program
>> on this bit, but it wouldn't take much to fix just by having an extra 
>> piece of
>> data stored with the station record ("how many digits of precision did we
>> decode from the packet's position fields?") and drawing a circle around 
>> the
>> station marker if that circle would be big enough to be visible)  This, 
>> again,
>> is all that Bob said.
>> All of this is completely independent of the precision of the underlying
>> map data (which Bob never mentioned), and dependent only on the number of
>> digits of position that come in and how zoomed in the map is, which the
>> programmer of the APRS application certainly *DOES* have access to.
> Correct (Like I ever stand a chance of correcting Tom?).
> I got an evil glint in my eye while reading the above...  I think we
> _should_ capture that data in Xastir and use it to "obscure" the
> plotted position as one zooms in.  It would make the advantages of
> Base-91 and OpenTrac positions that much more evident!
> All those running Mic-E protocol or standard APRS-format packets
> would only be able to see their position down to roughly 60 feet.
> Base-91 positions would capable of showing down to 2 or 3 feet
> (OpenTrac much better yet), capable of displaying the accuracy of
> non-SA/WAAS/DGPS-corrected GPS positions.  ;-)
> --
> Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
> "Lotto:    A tax on people who are bad at math." -- unknown
> "Windows:  Microsoft's tax on computer illiterates." -- WE7U
> "The world DOES revolve around me:  I picked the coordinate system!"
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