3D Specialist - because the world (probably) isn't flat | Reality Capture | Georadar (GPR)
Is sub-centimetre accuracy realistic for a GNSS topo Survey? Here we tested the Trimble Geospatial R12i GNSS positioning against the Trimble S7 total station, using Integrated Surveying and a tripod to stabilise the pole while measuring the same points with both systems. The accuracy of less than a centimetre horizontal and vertical error from a quick GNSS measurement offers a viable option to total station measurement for many project requirements. - GNSS points are 5-second observations. - Total station points are single face measurements. - Total station fixed points measured with mini-prism (100 mm prism height). - Fixed points were established with the average of two GNSS observed control points, with the pole rotated 180° between the 30-second observations to reduce the effects of any equipment imbalances. As ever, the project and environmental conditions should be suitable for GNSS measurements, and the accuracy feedback in Trimble Access should be observed. #surveying #vermessung #rtk #gnss #trimbleS7 #TrimbleR12i #TrimbleAccess #workflow #productivity #geospatial
Agnieszka Sójka
11mo
The difference between TPS and GPS will depend on the scale used in TPS. If you are using scale 1 pretending the Earth is flat you will get even a few centimetres difference over 100mbetween both. It will depend on the location of survey, coordinate system used etc. GNSS will give you good absolute accuracy, TPS better relative accuracy. For test like these it is important to state the coordinate system (projection) the test is done in as the biggest differences between TPS and GNSS comes from coordinate system scale (projection)
Kurtis Grantham
11mo
Great set up. Testing on the arms I bet though!
David Woolley, PLS
11mo
Actually, as much as we want to believe, this is simply not true. The R12i GNSS instrument specifications state the RTK vertical is 15mm (presumably) at one sigma - this is 30mm (3CM=0.09') at two sigma with 10% of the measurements falling outside of the 30mm. Trimble has a vested interest in making and advertising these instruments as accurate as possible. If their tens of millions of epochs of testing could report better accuracy, they certainly would do so. A couple of parking lot shots is meaningless as to restating Trimble's testing to determine their specifications. Take Trimble's word for it before you get sued for negligence and have to write a check for damages. Check out OC CLSA videos, video 4, for more information: https://lnkd.in/g9wu8GQK
Greg Bull
11mo
Integrated surveying is the best!! Awesome for when you're doing a big topo, and there's a few trees or structures in the way of the gnss. Plus, gps search gets a whole lot more accurate with the reciever on top!!
Gord Wallace
11mo
Love this
Ivan A.
11mo
Uesd it with Land2maps . Great tool
David Mitchell
11mo
Regardless of the merits of the different equipment setups, do we really need sub-centimeter accuracy for topographic surveys? As measurement specialists, accurate and reliable results are of course crucial, but we need to keep in mind the purpose of the survey and the level of accuracy associated with the purpose. I have not come across any specs for sub-cm accuracies for topographic mapping in 30 years of surveying.
Lakhan Chauhan
11mo
Good to know! Robert Greenhalgh
John Preston
11mo
This is not really a real world comparison. Who would want to wait 5 seconds between each GNSS observation when doing a topo? Time is money. What you should really be comparing is the accuracy of a one second GNSS observation vs total station.
Survey Party Chief with Oneida Engineering Solutions
11moI’ve encountered many office staff afraid of GNSS collection because it didn’t work well for them in the 90’s & 00’s. The R-12i running there has a dual frequency band to mitigate any multi path error reliably. As well the instrument is connected to 26 birds - huge observation density for accuracy. Those superstitions surrounding GNSS collection are simply antiquated. That quick release mount on the glass is an interesting setup! It explains the 2.034 rod height on the 12i. Curious to learn more about your survey outfit in Leeds!