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ZL3AI > APRDIG 19.03.07 00:25l 148 Lines 4833 Bytes #999 (0) @ WW
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To : APRDIG@WW
Today's Topics:
1. Re: RE: Core Server Port changes (Gerry Creager)
2. Re: Core Server Port changes (Gerry Creager)
3. filtering using shape files (John Habbinga)
4. RE: filtering using shape files ('Scott Miller')
5. Re: filtering using shape files (Steve Dimse)
----------------------------------------------------------------------
Message: 1
Date: Sat, 10 Mar 2007 11:37:23 -0600
From: Gerry Creager <gerry.creager_at_tamu.edu>
Subject: Re: [aprssig] RE: Core Server Port changes
A fourth server is hidden away and will take the load as required.
Gerry
Cap Pennell wrote:
>Hi Gerry. Thanks to you guys for the new ports! Cool!
>
>One tiny detail: at one point the http://core.aprs.net website still
>mentions four servers (instead of three).
>
>"rotate.aprs.net will pseudo round-robin load balance across all four
>servers automatically."
>
>73, Cap KE6AFE
>
>>-----Original Message-----
>>From: Gerry Creager
>>Sent: Friday, March 09, 2007 13:40 PM
>>
>>The APRS-IS Core Servers have today added several new port connections,
><snip>
--
Gerry Creager -- gerry.creager_at_tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
------------------------------
Message: 2
Date: Sat, 10 Mar 2007 11:38:29 -0600
From: Gerry Creager <gerry.creager_at_tamu.edu>
Subject: Re: [aprssig] Core Server Port changes
Noted that last night in additional testing. This has been a rough month
to try to do something useful: Work keeps getting in the way.
I am seeing lots of activity now on that port. Thanks for identifying the
issue.
73 gerry
John Habbinga wrote:
>first.aprs.net:24579 doesn't seem to do anything.
--
Gerry Creager -- gerry.creager_at_tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
------------------------------
Message: 3
Date: Sat, 10 Mar 2007 13:50:27 -0600
From: "John Habbinga" <kc5zrq_at_gmail.com>
Subject: [aprssig] filtering using shape files
Has anyone considered developing a filter that uses shape files? It would
be really nice to select specific counties, regardless of their shape, and
only receive data from those areas. You could build a filter for all of
Texas that doesn't include Oklahoma, Arkansas, Louisiana and New Mexico.
I would imagine that it would require that the operator of javAPRSSrvr, or
other server, to download the shape files to their computer. A filter
would then be defined by the user.
------------------------------
Message: 4
Date: Sat, 10 Mar 2007 13:51:02 -0800
From: "'Scott Miller'" <scott_at_opentrac.org>
Subject: RE: [aprssig] filtering using shape files
I've done it, but only for database access and not live stream filtering.
I've got an Oracle Spatial database on my development machine, and I'm able
to import shape files and run queries against them. For example, I can have
it select all stations in Santa Barbara county, all stations in Oklahoma
within 1 mile of Interstate 40, and so on.
I think you'd need to find a different solution for stream processing,
though.
Scott
N1VG
>-----Original Message-----
>
>Has anyone considered developing a filter that uses shape files? It would
>be really nice to select specific counties, regardless of their shape, and
>only receive data from those areas. You could build a filter for all of
>Texas that doesn't include Oklahoma, Arkansas, Louisiana and New Mexico.
>
>I would imagine that it would require that the operator of javAPRSSrvr, or
>other server, to download the shape files to their computer. A filter would
>then be defined by the user.
------------------------------
Message: 5
Date: Sat, 10 Mar 2007 17:12:08 -0500
From: Steve Dimse <steve_at_dimse.com>
Subject: Re: [aprssig] filtering using shape files
On Mar 10, 2007, at 4:51 PM, Scott Miller wrote:
>I think you'd need to find a different solution for stream processing,
>though.
The algorithm is well known and it is easy to find code examples on the
internet. Distilled, the idea is to draw an imaginary line segment between
the point under test and an arbitrary distant point (known to be outside
the shape, e.g. the north pole), then check mathematically to see if that
imaginary line crosses each of the line segments in the polygon under test.
If the number of crossings is odd, the point lies within the polygon. If
the number of intersections is zero or even, the point lies outside the
polygon.
Steve K4HG
------------------------------
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End of aprssig Digest, Vol 33, Issue 12
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