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pointing" precision

sir what is meant by pointing precision

most theodolite specifications are stated in terms of a "pointing" precision, the ability to repeat a reading to a single point

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  • Land Surveyor


    Assuming that what you mean is "What is the standard error of pointing the telescope of a good quality total station or theodolite at a well-defined target in sharp contrast?", the answer is that it depends mainly upon the magnification of the telescope. If you were unable to point a first-order theodolite at a target with a standard error of point well under +/-1", then the problem was probably as much with the target as with the observer.
    Billy I got somethingĀ after some research check it out
    Ā The usual empirically derived values for the standard error of point are:

    Distant targets in poor contrast: 20"/M, where M = Telescope magnification

    Close range targets in good contrast : 12"/M

    So, for a 30X telescope the pointing uncertainty would be expected to fall in the range between +/-0.40" and +/-0.65". Naturally, much worse results can be obtained under adverse conditions.

    • Hello Raymond, All thisĀ  plays intoĀ  this .Ā  But your Instru. can be set, or a DataĀ  Coll. on average's of it's readings exam.Ā  most's are 1 shot select,Ā  3 shot avg. select,, the 3 shot avg. wouldĀ  be a exam. of this, some have more options to select ,Ā  also you angles can be taken and added many different ways then divide for a avg. your sightings can be arrange in direct to indirect,Ā  there many different versions of this closure'sĀ  Your instu., no matterĀ  how good the calibration is contains a small error, that whyĀ  you reverse your sighting , if you setup andĀ  bs a point, make sure theses are set at the same dist. flip your barrel and mark a point like on a batter board , then reverse scope back sight the same point flip the barrel and mark another point beside the first one, this is the error in your instru. If they are the same that is good, Ā  divide this dists. from these marks and mark it , this is the true line 180 degrees of your instru. . the distance that you have chosenĀ  like , 200,500,1000. feet or meters,Ā  will reflect the error foundĀ  on each one ,this is also a good way to set trueĀ  line on a line. now this goes back to why you take multiplies readings, then they are avg,to correct the values of the sum because every dist. shot is not the same, and your instru. angles can be multiply in one directions that good, but it is better to multiply forward and reverse these sums will add up to your pointing precision value.Ā  I hope this help's youĀ  andĀ  anyone with this ?.

  • Hi Raymond, The only way this could be used in a total station is in your settings, on how many winding's you have set on your angle's, then it will average it to one, and how many shot's are set for it to take , to average it to one . this can also be found in most data collectors config. or settings. This is all i can think of in referenceĀ  to a total station, but i have never seen this label on any program or setting. If you find one please let me know.

    Raymond keep them a comingĀ Ā Ā  still a good ?


    • GEO Ambassador

      great stuff Billy! Ā Nice assist!

      • Thanks ,Ā  Survenator and Justin. and Raymond for this ? This is also a ? given on many surveying test. Point Precision ,Ā  and does accuracy and precision mean the same thing.Ā  True or false


  • Hi Raymond,Ā  You will not find this in or on any thing in your total Station.If you do please let me know.This will be a learning experience to me,this is not a program or setting in the gun , this is used in terminology, used in surveying.If it is not can someone tell were it is. And thank youĀ  again my Friend.I hope this helps Raymond ....


  • Hi Raymond, Yes it is good that Survenator to point out thatĀ Ā  Accuracy and Precision are not the same.One defines the other,Ā  in this case Precision defines the Sum.Ā  To define the Accuracy of the Pointing.But keep in mind they are not the same. I hope this help anyone with this ? Also some more, Ā  Running multiplies turn's with level run , multiplies rod face readings (first order levels) the list goes on. for this terminology . still good ? Raymond.


  • Survey Legend

    Great explanation Billy! Ā Also Take a look at thisĀ and the attached docs... hope this helps..

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