dear all good morning,
i would like to know how can i measure correct instrument height for the traversing at a new site,because when i am measuring the measuring tape is not in vertical to reference station to instrument height mark.
that is why there is showing error in all elevation measurements.
please explain me good suggestions for proceed my work.
thanks
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Replies
If your measured heights with tape are 4.5' to 5.5' then simply subtract 0.015 and this should get you very very close to true height. Sounds to me you might have some other error going on because typically the survey total stations will not measure vertical that accurate consistently to come to the conclusion that the height of instrument is the problem. How long are the shots being taken. That makes a big difference as well.
If you're using Leica, then you have ways to do that. Using a height meter is for one. Another is to employ the "Transfer Height" application if you're using the SmartWorx data collection system.
Horizon announced last year I gues that it had developed a new way to measure HI. I did not see it how it works.
In extreme cases, level to a stud adjacent to the traverse station. Set the instrument VA to 90 and read the "instrument height" to a staff above the TBM. I have used this method when intersecting from 2 instruments when collimation heights were critcal.
If you are getting an error in just V. I would also suggest doing a 2 peg test as equipment such as Trimble corrects for this height measurement error in the software and the Total Station may need adjusting.
It is not necessary typically to consider such an "error" since it is compensating. In other words all the instrument heights, if measured the same way, will contain the same error therefore it has no effect on the result. However you can compute the difference between the true height (TH) of the instrument and the measured height (MH) of the instrument by considering the width of the instrument divided by 2 (WI/2). MH squared minus the WI/2 squared equals TH squared.
Or C2 - A2 = B2