Ellipsoid / Geoid Changes when updated to new 2.09 Version

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Ellipsoid / Geoid Changes when updated to new 2.09 Version

Postby cycleslip » Wed Mar 11, 2009 9:12 pm

Has anyone had a problem when reusing .ref and .loc files after they upgraded the software version to 2.09?

for some reason the elevations misclose by 13-16 m (depending on the locations) which "conveniently" is the geoid - ellipsoid difference for this area.....

it seems almost like the new version has a built in geoid.


any ideas?
cycleslip
 
Posts: 2
Joined: Wed Mar 11, 2009 9:05 pm

Possible Geoid Issues

Postby bhammer » Thu Mar 12, 2009 1:53 pm

If you go into Equip / Localization / GPS tab = do you have a Geoid Set
If so, I would recommend tapping "Geoid File" button / tap the Red X in the upper right. Then check the elevation in Mon Skyplot or Stakeout a known point.

Are you using a Geoid and a .loc? How is the elevation effected by turning the Geoid on and off?
bhammer
 
Posts: 11
Joined: Tue Oct 23, 2007 8:43 pm
Location: Watertown, MA

Postby cycleslip » Fri Mar 13, 2009 2:01 pm

No, we never use a geoid file because we localize to known benchmarks with have the orthometric elevation incorporated. (I don't think we even have any geoid files anyway)

It has come to my attention that this has happened (rarely) before the software update, so it may not be a problem related to 2.09 specifically.

Looking at the raw and loc files more closely it's almost like the data collector is doing the localization correctly the first day and then recording the wrong info into the .loc file for the ellipsoid elevation. It's when we come back to the job another day is when we notice the problem.

The funny thing is, it doesn't happen all the time. It's just some simple addition and subtraction to put the right number in the .loc file, I don't understand why this problem occurs.

Here's an example:

Localization file:
"<record>"
Lat" value="51.0441703698404"></value>"
Lon" value="-114.0480717831215"></value>"
Ellipsoid_Elv" value="1053.3337167519078"></value>"
Local_X" value="-3372.7062999999998"></value>"
Local_Y" value="5657912.7291999999000"></value>"
Local_Z" value="1042.0050000000001"></value>"
HRMS" value="0.0147610975"></value>"
VRMS" value="0.0172"></value>"
Use_Horizontal" value="Yes"></value>"
Use_Vertical" value="Yes"></value>"
Description" value="924"></value>"


Raw file:


BP,PN,LA51.024257521403,LN-114.024891323349,EL1041.2862

LS,HR1.9195

GPS,PN1924,LA51.023901335198,LN-114.025305827010, EL1038.919700,--ASCM 379248

--GS,PN1924,N 5657912.6581,E -3372.6943,EL1042.0070,--ASCM 379248
--DT01-22-2009
--TM10:10:32


In the Loc file, the Ellipsoid Elev is recorded as 1053.334, which is absolutely ridiculous because the orthometric height at the spot is 1042.005 (the ellipsoid is around 16m lower in our corner of the universe)

In the Raw file, the GPS is recording a height of 1038.920 (not including rover height)

Any Ideas?
cycleslip
 
Posts: 2
Joined: Wed Mar 11, 2009 9:05 pm

Postby bhammer » Fri Mar 13, 2009 3:58 pm

Please e-mail this question to support@carlsonsw.com so that we in Tech Support may help you resolve this issue.
bhammer
 
Posts: 11
Joined: Tue Oct 23, 2007 8:43 pm
Location: Watertown, MA


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