Geoid correction gives wrong value
Latest version of Locus on a Google Galaxy Nexus, in a place that is ~35 m above sea level.
Disabling both pressure sensor and offset correction, I get 15 m in a particular moment (it can vary depending on atmospheric weather, number and position of satellites, etc)
If I enable "offset from NMEA" sentence, I get 45 m, that is slightly better (although overcorrected)
If I enable "automatic offset" (i.e. from internal geoid model, if I understand correctly), I get -612m!
At first I thought that it could be a double correction (i.e. data comes form the GPS already corrected for the geoid, and I'm asking Locus to correct them again). However, I checked on internet and the geoid value here is -29m, so there is no way I can get -612 even applying it twice.
The same problem 
Hello Giacomo,
nice description, but quite useless for me, sorry.
Please post me source of HGT files and exact coordinate, where I can test it. Thank you
Hello Giacomo,
nice description, but quite useless for me, sorry.
Please post me source of HGT files and exact coordinate, where I can test it. Thank you
Hi Menion,
I did a more precise test. I stood in the parking lot of my home, with good satellite visibility, and started to record a track; then, every minute, I changed the offset setting.
The track is attached. Here is how to interpret it (times are approximate):
from 0 to 60 seconds: offset OFF; oprimize gps altitude OFF
from 60 to 120 seconds: offset ON, automatic correction; offline optimization OFF
from 120 to 180 seconds: offset ON, nmea correction; offline optimization OFF
from 180 to 240 seconds: offset OFF; offline optimization ON
Pressure sensor was OFF during the entire test.
The "real" altitude of the place as obtained from a variety of sources (including the details of the point in LOCUS) is about 28 m.
Hi Menion,
I did a more precise test. I stood in the parking lot of my home, with good satellite visibility, and started to record a track; then, every minute, I changed the offset setting.
The track is attached. Here is how to interpret it (times are approximate):
from 0 to 60 seconds: offset OFF; oprimize gps altitude OFF
from 60 to 120 seconds: offset ON, automatic correction; offline optimization OFF
from 120 to 180 seconds: offset ON, nmea correction; offline optimization OFF
from 180 to 240 seconds: offset OFF; offline optimization ON
Pressure sensor was OFF during the entire test.
The "real" altitude of the place as obtained from a variety of sources (including the details of the point in LOCUS) is about 28 m.
Hello,
thank you very much for your testing. You found out very serious issue, that happen in case, Geoid correction should be below 0. Omg, I can't understand, such issue were in Locus for such long time.
Thank you!!
I'll release one more BETA version 3.1.3.11 probably today evening (UTC+2) ( https://plus.google.com/communities/105669867009952671671 ), so if you will have a while and taste to test, it will be welcome.
Hello,
thank you very much for your testing. You found out very serious issue, that happen in case, Geoid correction should be below 0. Omg, I can't understand, such issue were in Locus for such long time.
Thank you!!
I'll release one more BETA version 3.1.3.11 probably today evening (UTC+2) ( https://plus.google.com/communities/105669867009952671671 ), so if you will have a while and taste to test, it will be welcome.
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