I am writing to you this email because I have not been activated on your forum of your website even though I become a member. I hope I can get any reply from you.
We are using DigiTerra Explorer Professional 188.8.131.52. My question is about Altitude and Height Above Ellipsoid fields. For Altitude the help menu says “Field value will be the height of the geometry = Mean Sea Level (MSL) if a geoid separation value is specified. On the other hand, again accoding to the help menu, HAE is the height above WGS84 (assuming data coming from GPS). It has been calculated using MSL and Geoid Undulation in NMEA GGA sentences, h= H (MSL)+N(geoid undulation).
Here is the question. For my project I am defining two fields: Altitude and HAE with no geoid file (so geoid undulation is always zero.) and antenna height (or upward offset) that is zero also.
When I get height using GNSS Survey (3 or 5 epochs), those two fields altitude and HAE must be equal but they are not. Sometimes there are 10 cm differences sometimes 70 cm sometimes. When I changed epoch time to 1 seconds, they are equal.
Would you please let me know how DigiTerra Explorer calculates those two fields, particularly for the case of epochs more than 1 second? Also let me know what I am missing?
Please let me know if you need further information about the question.
Eray SEVGEN [Mr.] | Geomatics Engineer, M.Sc.
The difference between "Altitude" and "Height Above Ellipsoid" is the following:
Altitude: this is the Z coordinate in the local projection system you are using after the received WGS84 LAT, LON, HAE position has been transformed into the local spatial reference system.
HAE (Height Above Ellipsoid): this is the received Height value above the WGS84 ellipsoid (without transformation)
Comment: You cannot change the epoch time on the GNSS Surveying panel, this is a misunderstanding. It is planned however to be able to average positions by time also. We are currently averaging by the number of received positions with the Mean option - if you are thinking on this.
More information about the GNSS Surveying panel available at: https://digiterraexplorer.com/downloads ... survey.htm
If any further question arises please do not hesitate to let me know. We are always here to help!
Senior Product Manager