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elevation not correct

Maybe some on can help me with this?

Have done a test project with 3D X-8 M here on Aruba.

We use 3 GCP because of the small area. Also we did a check with rtk gps on the area. I have found errors of 30 to 50 cm in the elevation? How is this possible?

The report give a 3D accuracy of 3 to 4 mm?

any help will be welcome.


thank you in advance


Jairo Maduro

3D surveying

Hi Jairo,


Did you use the RTK gps for your GCPs that you used for data processing, or just to verify the accuracy? Oliver put out a webinar (on improving accuracy) that might point out multiple reasons for the accuracy errors you’re reporting, but my guess would be that you’re within the range of expected elevation error if the project did not use the RTK GPS (especially for elevation, which I believe has an accuracy range of 2x-3x the GSD). 


P.S. - Can you attach your processing report? 

Hello Derrick,


We used RTK gps for the GCP’s and to verify the accuracy.


I will send you the report on the support mail.


thank you