[Az-Geocaching] Find the center
Robert & Linda Smith
listserv@azgeocaching.com
Tue, 27 Apr 2004 16:55:43 -0700
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I fear I've opened a can of worms with my question. Very interesting
read on all of your comments. If and when I get this together it will
not be as hard as several have suggested. No math, just a suggestion as
to where you might want to park and then go to approximate center.
Thanks again, Bob Smith, 1/2 of Team Petite Elite
David Thompsen wrote:
> 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
>
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I fear I've opened a can of worms with my question. Very interesting
read on all of your comments. If and when I get this together it will
not be as hard as several have suggested. No math, just a suggestion
as to where you might want to park and then go to approximate center.<br>
Thanks again, Bob Smith, 1/2 of Team Petite Elite<br>
<br>
David Thompsen wrote:<br>
<blockquote type="cite"
cite="mid20040426150037.3137.qmail@web12306.mail.yahoo.com">
<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 <a class="moz-txt-link-rfc2396E" href="mailto:sstringh@stringham-family.org"><sstringh@stringham-family.org></a></i></b>
wrote:</div>
<blockquote class="replbq"
style="border-left: 2px solid rgb(16, 16, 255); padding-left: 5px; margin-left: 5px;">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>
<a class="moz-txt-link-freetext" href="http://www.geocaching.com/seek/log.aspx?LUID=e0d67a76-96ce-4797-a186-0de15bfff37a">http://www.geocaching.com/seek/log.aspx?LUID=e0d67a76-96ce-4797-a186-0de15bfff37a</a><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>
</blockquote>
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