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Heights are 30 metres out for MSL Output

Source data: ebee images in WGS84, no GCP’s.

Desired output: WGS84 (x and y), vertical datum: heights relative to MSL on EGM 2008 geoid.

Heres the issue: The heights after selecting MSL are still showing a negative value.

We know the geoid/ellipsoid separation is approx -33m.

 

After entering -33m in the next option, results after Optimisation are still showing negative numbers.

Its as if the offset is not being applied by Mapper.

Also - if I change the offset value to positive 33m, the resultant heights after optimisation are -90m!

 

The whole thing is completely weird. All I want are orthometric heights relative to MSL.

Hi Philip,

We have already solved the issue via personal support :slight_smile:
However, I would like to comment on this Forum post, too, so that more people with similar issues can be helped!

The problem is related to the automatic detection of the images’ altitudes. The images’ altitude was detected as egm96 altitude. This is not correct for your case. The sensefly drones, by default, give ellipsoid altitudes (for the images). Changing the images’ altitudes should solve the problem.

Let us know if you get similar problems in other projects.

Have a nice day,
Christina

 

The images are incorrectly adjusted for heights relative to EGM96 geoid on import, rather than having raw ellipsoidal /spheroidal height values. Only an eagle eyed user would spot this :slight_smile:

The solution is to manually select WGS 84 during image import, rather than replying on Mapper Pro to do it automatically.

 

It took me a week, but we managed to find the systematic error.