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Why Independently Reproducible Bearings are Bad

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(@kent-mcmillan)
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Virgnina &cloudy days

> Kent, can we still do a sun shot if it's overcast? The crew is wondering if they should wait around till the clouds part so they can get a sun shot?

No, if the sun never shines in New Hampshire, you're out of luck. Everywhere else though, solar observations work fine. What it pretty much boils down to is you can spend more time arguing why you'll never be able to make decent solar observations or you can just go ahead and make decent solar observations and let someone else explain why THEY can't do them. :>

 
Posted : May 6, 2013 10:49 am
(@shawn-billings)
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Virgnina &cloudy days

like like like

 
Posted : May 6, 2013 3:04 pm
(@perry-williams)
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Last Word

Just wanted to get in the last word on this thread.

 
Posted : May 7, 2013 8:12 am
(@james-fleming)
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Perry

> Just wanted to get in the last word on this thread.

If you think you can get the last word in, you might want to look up "gullible" 😉

 
Posted : May 7, 2013 8:42 am
(@stephen-ward)
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Perry

Given surveyors inclination toward competitiveness and stubbornness, this thread may go on for months if it becomes a contest to have the last word. B-)

 
Posted : May 7, 2013 9:04 am
(@bill93)
Posts: 9834
 

Last Word - zymurgy

At least that's the last word in my dictionary. So even if someone posts later I had the last word.

 
Posted : May 7, 2013 11:29 am
(@perry-williams)
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in an argument with my wife, I always get the last words....

Yes, Dear.

 
Posted : May 7, 2013 3:51 pm
(@loyal)
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zythum...

A malt beverage brewed by the ancient Egyptians.

Webster's New Twentieth Century Dictionary
Second Edition 1979
Unabridged
Page 2120

B-)
Loyal

 
Posted : May 7, 2013 4:50 pm
(@kent-mcmillan)
Posts: 11419
Topic starter
 

> Interestingly, when the the 1993 and the 2012 surveys, each as its own independent system, are correlated using least squares, the orientation difference between the two is only one arc-second. Results are as follows:
> (Course 1 = Pt 1 to 2 ... 6 = Pt 6 to 7)
> [pre]
> Point Residuals (ft)
> No vN ... vE
> 1 - -0.010 ... 0.001
> 2 - -0.012 ... -0.009
> 3 - -0.006 ... -0.012
> 4 - -0.013 ... -0.006
> 5 - 0.004 ... 0.006
> 6 - 0.012 ... 0.011
> 7 - 0.026 ... 0.009
>
> Translation:
> dN = 0.0129
> dE = -0.0036
> Rotation:
> theta = 00°00'01.0"
> Scale: unity
> [/pre]

Considering that the bearings from the 1993 survey were expressed in the Texas Coordinate System of 1927 and those from 2012 in the Texas Coordinate System of 1983, and that grid North of each system differs by about 0.3" from the other, the rotation parameter derived in the Helmert transformation (I assume) may well partly reflect that systematic difference.

I'm a bit surprised that the scale parameter of the transformation is 1.000000. I'd expect some minor variation and will have to check the calculation to believe it.

 
Posted : May 7, 2013 5:09 pm
(@deleted-user)
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Zzzz Zzzz Zzzz Zzzz Zzzz Zzzz Zzzz Zzzz

finally some peace and quiet..

but I sure would like to know if there are any standards for surveying in the Live Free or Die state...probably not....only trees which brings me to one of my favorites that I have posted before..
Before he talked to chairs, he talked to trees,,, 🙂 ,

[flash width=560 height=315] http://www.youtube-nocookie.com/v/nn8YubD01sk?hl=en_US&version=3&rel=0 [/flash]

 
Posted : May 7, 2013 8:55 pm
(@kent-mcmillan)
Posts: 11419
Topic starter
 

> Considering that the bearings from the 1993 survey were expressed in the Texas Coordinate System of 1927 and those from 2012 in the Texas Coordinate System of 1983, and that grid North of each system differs by about 0.3" from the other, the rotation parameter derived in the Helmert transformation (I assume) may well partly reflect that systematic difference.

Footnote: I see that I actually calculated the angular difference between TCS of 1927 Grid North and TCS of 1983 Grid North and found it to be 0.501 arc seconds in the vicinity of the example originally posted.

 
Posted : May 7, 2013 9:18 pm
(@perry-williams)
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Zzzz Zzzz Zzzz Zzzz Zzzz Zzzz Zzzz Zzzz

> finally some peace and quiet..
>
> but I sure would like to know if there are any standards for surveying in the Live Free or Die state...probably not....only trees which brings me to one of my favorites that I have posted before..
> Before he talked to chairs, he talked to trees,,, 🙂 ,
>
> [flash width=560 height=315] http://www.youtube-nocookie.com/v/nn8YubD01sk?hl=en_US&version=3&rel=0 [/flash]br>
NH lets us use any north we feel like. It's called metes and bounds for a reason.

 
Posted : May 11, 2013 11:42 pm
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