I have done a survey 4 months ago, but for accuracy proposes when I repeat it again with tow kinds of prism (in total station menu was selected just mini prism).
1 Lieca round prism
2 lieca mini prism
But the result shown me the objects relocation than preveus work, in none systematic manner, a building corner the same location the other deffren or have skew than preveus work or other building in correct location in which was read a complete building by the same prism mini or round.
Any suggestion or ideas?
This Content Originally Published by a land surveyor to Land Surveyors United Network
Yes. different prisms have different offsets, Is normally written on the prism. Leica round is 0mm (or -30mm) to other manufacturers
It's wise to check the prism's you are using.
Be aware of the fact that all the Leica prism's incorporate a standard difference of -/-34,4mm, which is regarded as Leica 0 (zero) value.
So I would like to propose a small test with 3 tripods in line. 1--2--3.
Take a distance measurement from 1 to 2 plus 1 to 3.
After that that set up on 2, and measure the distance to 1 and 3.
Compare the distances.
The first distance uses only 1x the prism constant value. When you set up from position 2 it's using 2x the prism constant value.
If possible use a seccond total station to,eleminate system failures.
hope this helps.
you can always define a new prism name + constant value in your instrument settings.
Hi NAYUM KHAN
May you say in English plz
your prism constant is very valid.Normally a -30mm constant is applied for large prisms.A small prism has a different prism.
Set up test locations (possibly inside) and check everything periodically
The mini and the regular circle prism should have the same accuracy but the 360 degree prisms are typically 6" or 8" rated so aren't advisable for long traverses