Did a job north Dallas today which is over 200 miles from my normal work area. We logged into the local Leica network base and started collecting data. If we cared about the vertical solution we would have checked into a local NGS BM but since we where only concerned with a relative horizontal we just collected data.
When we downloaded the points I noticed that the verticals where about 85 feet different that what I would have expected for this area. Sure enough I did some checking and we had travelled outside the limits of the geoid03 file I had created for working in the Houston area.
If this had happened with our old trimble gps and TDC1 we would have gotten a warning that it could not process the ortho elevation because it did not have a valid geoid file. With the SurvCE Surveyor Plus DC we didn't get a warning, this is not normally a problem in Houston because if our elevations are off by 85 feet we would be getting negative verticals but I can see where if working in an area with terrain and you wandered past your geoid limits all the sudden your elevations are out by 85 feet and you might not notice it.
Is there a setting in the DC that would warn of this.
Robert,
There must be a setting in there somewhere. I run SurvCE, and always get a message when we are outside of our Geoid area.
Maybe you have an older version? Just a guess.
FYI- I experimented with making the Geoid coverage area larger (Geoid 2009), but it seems to bog the collector down...I try to keep it under 80 miles or so.
Thanks I will ckeck and see if we missed something.
Robert,
Be it a subtle item to notice on your data collecter, but while taking your RTK shots,if the Elevations are labled "Orthometric Height", you can be confident you have a Geoid Model attached to the coordinate system/job.
While taking RTK shots, if the height labels indicate "Ellipsoid Heights", you may have out-run your local Geoid Model Field file. Fallen off the edge of the world, so to speak. Or the local Geoid Field file is simply not attached to the Coordinate System/Job.
-BbB
Robert,
If you are collecting data for export into another system I think you can just replace the gem file with one that covers your area before you export. The alternative is to import it into LGO for export.
Robert
We have had this problem before and It seemed liked earlier versions on Carlson gave a warning, however I cant recall any newer releases (2.0 and above) giving one.
We switched in 2010 to the VIVA collectors from Carlson (magically all of our Carlson vs Leica issues went away) and have been able to upload a geoid file for the entire state so its not a problem now.
That works I reprocessed the raw file in carlson xport and it calculated all the orthos
We are also using the latest version and I don't see a warning but I think the hint about the type of elevation may help. Is the Viva a Carlson collector or a Leica collector?
VIVA is a Leica controller, Leica has a version of SurvCE to run on their collectors.
Robert
Viva is the new Leica controller. It far exceeds Carlson's capabilities now in dealing with Leica.
FWIW, TDS will do the same thing if you are surveying in Tampa and still hooked into Alabama West.....:-S
The fix was simple, just wrote a spreadsheet with the corrections for elevation (never underestimate the value of an old school 3 wire level loop through control) and batched the file through it, all good. Once transformed to the correct coordinate basis it overlaid on aerials just fine.
Leica did (finally) wake up a bit. A lot more user friendly. But a bit of a heavy set-up I was told.
Bonus, their Viva solutions (icons and graphics) have a bit of a Facebook feel, that should attract the young workforce as well as reminding them to update/check their pages while @ work.
:beer:
