Aloha, Happy 2015!
What is the proper field procedure for creating redundant shots that will be used for LSA to a control network?
See attached image below for reference.
Let say I occupy pt. #1 and BS to pt #5. My FS point is pt. #2. Pt. # 6 is visible from my current OC #1. I take a side shot then I occupy pt. 2, BS pt.# 1 and FS pt. 3. Point #6 is not visible from any other points except points #1 and #5. So once I occupy pt #5 I take side shot of #6 again. Am I okay so far?
1. Do I need to occupy point #6 and take side shot #1 or #6? (depending which one I use for BS).
2. Should I complete my traverse loop without any side shots then setup again to collect redundant shots?
What do the pros do in the field?
Mahalo!
Occupy 6, if it was important to side shoot and you want to strengthen the LSA
If it is a tie to monument and not to be used in the lsa, then side shots from 2 points is acceptable as long is the inverse between to two side shots is within your error tolerance
I don't believe it's that important to occupy it as long as you turn angle sets to it from at least two of your main traverse points, but when doing an LSA I guess more is always better - It would give you a great check on your setups and HI/HT at 1 and 5.
Occupy 1, BS 5, FS 6, BS 2, FS 6.
Occupy 5, BS 1, FS 6, BS 4, FS 6.
Occupy 6, BS 1, FS 5.
Adjust.
Paul in PA
> What do the pros do in the field?
All or any of the above. It depends on how certain, and how precise, you need to be.
Once you occupy 5 you should certainly turn the angle 4-5-1 toi close the figure, but itn't doesn't always happen. And 4-5-6 is appropriate for redundancy, but not strictly necessary. Occupying 6 and turning 5-6-1 will greatly enhance your solution, but that would be a greater investment of time and often gets left out in practice. Unless 6 is a very important point.
If you are surveying in a world that is flat, buff white, and contained within an 8 1/2" x 11" rectangle you can get away with less. In practice you will want to compensate for the world's imperfections as far as you can afford to with extra measurements.
> Occupy 6, if it was important to side shoot and you want to strengthen the LSA
> If it is a tie to monument and not to be used in the lsa, then side shots from 2 points is acceptable as long is the inverse between to two side shots is within your error tolerance
Aloha, Blake:
Thank you very much your input.
> I don't believe it's that important to occupy it as long as you turn angle sets to it from at least two of your main traverse points, but when doing an LSA I guess more is always better - It would give you a great check on your setups and HI/HT at 1 and 5.
Aloha, Lee: Thanks!
I know you use S6...how many angles do turn for the controls with that gun?
Thanks!
> Occupy 1, BS 5, FS 6, BS 2, FS 6.
>
> Occupy 5, BS 1, FS 6, BS 4, FS 6.
>
> Occupy 6, BS 1, FS 5.
>
> Adjust.
>
> Paul in PA
Aloha, Paul: Thanks!
> > What do the pros do in the field?
> All or any of the above. It depends on how certain, and how precise, you need to be.
>
> Once you occupy 5 you should certainly turn the angle 4-5-1 toi close the figure, but itn't doesn't always happen. And 4-5-6 is appropriate for redundancy, but not strictly necessary. Occupying 6 and turning 5-6-1 will greatly enhance your solution, but that would be a greater investment of time and often gets left out in practice. Unless 6 is a very important point.
>
> If you are surveying in a world that is flat, buff white, and contained within an 8 1/2" x 11" rectangle you can get away with less. In practice you will want to compensate for the world's imperfections as far as you can afford to with extra measurements.
Aloha, Mark:
As always appreciate your detailed explanations!
I want to train myself to precise so extra field work is good for me and I am not on any deadlines 🙂
Looks like from all the post above, I should occupy #6. And I will!
Thank you so much!
Once you have the data in hand you can remark out the 5-6-1 tie and rerun the adjustment to see how much difference it makes to your final solution.
> Once you have the data in hand you can remark out the 5-6-1 tie and rerun the adjustment to see how much difference it makes to your final solution.
Aloha, Mark: Will do.
Might take longer than you think...
> I want to train myself to precise so extra field work is good for me and I am not on any deadlines 🙂
>
I'll be right out there to give you a hand!:-D
Might take longer than you think...
> > I want to train myself to be precise so extra field work is good for me and I am not on any deadlines 🙂
> >
>
> I'll be right out there to give you a hand!:-D
>
Aloha, Bob:
I am at it since 2012. The more I learn, the slower I perform. With knowledge comes responsibility! I thought I could do it in couple months when I started too:-$
The folks here groomed me pretty well. It is very humbling! I started with zero knowledge. I was inspired by the site to be the best survey student and it is a work in progress.
Might take longer than you think...
You had to show that, you are a bad, bad man yawami:-(
And turn that last angle, you wont regret it.
Might take longer than you think...
> You had to show that, you are a bad, bad man yawami:-(
Sorry MM... Could not help it when I saw RFC's post. I do get to be a mischievous monk once in a while right?:-D
>
> And turn that last angle, you wont regret it.
Will do! Thanks
> What is the proper field procedure for creating redundant shots that will be used for LSA to a control network?
What I would do is run the traverse that you've surveyed through an adjustment by least squares, using the standard errors of the angles and distances characteristic of the instrument you're using (preferably as determined by test) and the centering errors of instrument and targets over the control points.
If inspecting the relative error ellipses of the control points shows them to be larger than you want, then about all you can do is to add more measurements to network, meaning: remeasure angles and distances and add those to the adjustment.
All other things being equal, the ties to 6 from 1 and 5 will be of relatively little value.
It depends... usually 3 direct and reverse. The S6 is so fast it doesn't take much longer to add a set or two when needed.
> > What is the proper field procedure for creating redundant shots that will be used for LSA to a control network?
>
> What I would do is run the traverse that you've surveyed through an adjustment by least squares, using the standard errors of the angles and distances characteristic of the instrument you're using (preferably as determined by test) and the centering errors of instrument and targets over the control points.
>
> If inspecting the relative error ellipses of the control points shows them to be larger than you want, then about all you can do is to add more measurements to network, meaning: remeasure angles and distances and add those to the adjustment.
>
> All other things being equal, the ties to 6 from 1 and 5 will be of relatively little value.
Aloha, Kent:
Thanks for the input. I am yet to do the centering error for my TS. Got the poles and tribrach calibrated so far.
Thank you.
Not addressing directly your question (others have)...
When I run a traverse I try to sight something that can be seen by three or more stations, for example a radio tower or water tower. I then include that in the adjustment. I do not compute any lines individually, I compute them all simultaneously.
> When I run a traverse I try to sight something that can be seen by three or more stations, for example a radio tower or water tower. I then include that in the adjustment. I do not compute any lines individually, I compute them all simultaneously.
Angles only, or angles and distances. Is part of the objective to pick something far away, as opposed to just another station within the network?