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 Site calibration with predefined projection or with no projection no datum?

Vukasin Majkic's profile image
Vukasin Majkic posted 04-20-2023 10:24

So, could someone explain me what would be difference when doing site calibration with a job that has for example UTM projection set up or doing it with no datum no projection job. As far as i could see, in trimble access a no projection job with calibration gets 3-Parameter transformation and the job with UTM stays with 7-Parameter. I mean I get the same results while staking out  at the end, just wondering if there is any difference? 

Marian Plucinski's profile image
Marian Plucinski posted 04-20-2023 15:31

Are we talking GNSS only jobs, or GNSS + Total Stations or Total Station alone?

Scale factors can play a big role if you're constructing structures. Your stake out can be on the the money, but it doesn't mean that 100m on the ground = 100m on the grid.

I'd personally refrain from using any site calibrations, only using published Coordinate Systems. For the structures we're using Scale Factor Only 1.000000 setup on Access.

Site Calibration done wrong can look tip top on the screen and during set outs, but can me miles our, especially in elevation, from the local datum you're trying to tie into.