[Az-Geocaching] Find the center
David Thompsen
listserv@azgeocaching.com
Mon, 26 Apr 2004 08:00:37 -0700 (PDT)
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I've done a lot of puzzle caches, and one thing being left unsaid, maybe it's obvious, it that if you want to work the math... convert all waypoints to UTM. This gives you nice (x,y) coordinates to work with, which respond nicely to geometry and trigonometry.
As for the triangle, yeah, there's a lot of ways to define the "center". Intersection of medians, orthocenter, and circle touching all three points of the circle. I've seen puzzle caches using all of the above.
--Dave
Team Cowspots
Steven Stringham <sstringh@stringham-family.org> wrote:
When I did orbis - in Tucson, I used Autocad to calculate the center of
that triangle. The radius of the circle is only about 2 miles. And, that
had me off (because I was not taking the curvature of the earth into
account) about 900'. I then recalculated, and was still off, but came up
with another way to figure it out (because of the way the points are layed
out, it allowed me to do some triangulation on it).
Good luck.
http://www.geocaching.com/seek/log.aspx?LUID=e0d67a76-96ce-4797-a186-0de15bfff37a
> Robert & Linda Smith wrote:
>> Thanks Brian,
>> The page you listed is a very interesting read. I really enjoyed it
>> (didn't understand all of it) but enjoyed the read. I don't need to be
>> this close and accurate. A few feet this way or that is fine. I just
>> wanted to be close.
>
> Hopefully you are talking about 3 points that are fairly close together.
> The error actually gets large rather quickly.
> a couple points that are half the height or width of arizona apart can
> have an error of 1/4 mile if you don't calculate it correctly.
>
> Brian Cluff
> Team Snaptek
-----------------------------------------
http://stringham-family.org/
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<DIV>I've done a lot of puzzle caches, and one thing being left unsaid, maybe it's obvious, it that if you want to work the math... convert all waypoints to UTM. This gives you nice (x,y) coordinates to work with, which respond nicely to geometry and trigonometry.</DIV>
<DIV> </DIV>
<DIV>As for the triangle, yeah, there's a lot of ways to define the "center". Intersection of medians, orthocenter, and circle touching all three points of the circle. I've seen puzzle caches using all of the above.</DIV>
<DIV> </DIV>
<DIV>--Dave</DIV>
<DIV>Team Cowspots<BR><BR><B><I>Steven Stringham <sstringh@stringham-family.org></I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">When I did orbis - in Tucson, I used Autocad to calculate the center of<BR>that triangle. The radius of the circle is only about 2 miles. And, that<BR>had me off (because I was not taking the curvature of the earth into<BR>account) about 900'. I then recalculated, and was still off, but came up<BR>with another way to figure it out (because of the way the points are layed<BR>out, it allowed me to do some triangulation on it).<BR><BR>Good luck.<BR><BR><BR>http://www.geocaching.com/seek/log.aspx?LUID=e0d67a76-96ce-4797-a186-0de15bfff37a<BR><BR>> Robert & Linda Smith wrote:<BR>>> Thanks Brian,<BR>>> The page you listed is a very interesting read. I really enjoyed it<BR>>> (didn't understand all of it) but enjoyed the read. I don't need to be<BR>>> this close and accurate. A few feet this way or that is fine. I just<BR>>> wanted to be
close.<BR>><BR>> Hopefully you are talking about 3 points that are fairly close together.<BR>> The error actually gets large rather quickly.<BR>> a couple points that are half the height or width of arizona apart can<BR>> have an error of 1/4 mile if you don't calculate it correctly.<BR>><BR>> Brian Cluff<BR>> Team Snaptek<BR><BR><BR><BR>-----------------------------------------<BR>http://stringham-family.org/<BR>____________________________________________________________<BR>Az-Geocaching mailing list listserv@azgeocaching.com<BR>To edit your setting, subscribe or unsubscribe visit:<BR>http://listserv.azgeocaching.com/mailman/listinfo/az-geocaching<BR><BR>Arizona's Geocaching Resource<BR>http://www.azgeocaching.com</BLOCKQUOTE><p>
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