Correct Elevations

During start up when you set your parameters for your base setup, do you leave your elevation offset as ZERO and the JAVAD system is smart enough to give you proper elevations or are you suppose to input the height of base plus the height of the 1/4 to 5/8 adapter, (and is the adapter 0.23m?)?

The majority of the time, I am not really worried about the Z value, but when I work adjacent to the TN-Tombigbee Waterway, I need correct elevations to tie to their easements which are a certain contour elevation, which was derived from NAD27 and NGVD 29. And also for any future construction and engineering staking.

Thanks,
The Still Newbie
Garrett
 

Adam

Well-Known Member
5PLS
You need to enter the vertical hieght of the pole plus the adapter which is 25mm or .082' . If you are setting the base on a tripod you will need to measure the slant height to the green arrow on the t2 and use no offset.
 

APADDEN07

Member
Similar issue with NAD27/NGVD 29. FEMA flood elevations along the shores of Lake Champlain are referenced to NGVD29, but when I attempt to setup a job in NAD27/NGVD29 i get a ? next to the coordinate system. When that coordinate system is selected, the project settings screen now shows WGS84(ITRF2008), instead of NAD27/NGVD29. If I try to use geoid12B(conus) it changes my heights to NAVD88. It seems like I'm just missing the proper geoid (I think clarke1866 ?) LS+ Running J-Field 3.0.9.439.

It does appear that if I change to the "?" NAD27/NGVD29 coordinate system AFTER the project is created with WGS84(ITRF2008), it allows me to change the coordinates, but I haven't tested that in the field.
 

Vladimir Prasolov

Well-Known Member
JAVAD GNSS
Similar issue with NAD27/NGVD 29. FEMA flood elevations along the shores of Lake Champlain are referenced to NGVD29, but when I attempt to setup a job in NAD27/NGVD29 i get a ? next to the coordinate system. When that coordinate system is selected, the project settings screen now shows WGS84(ITRF2008), instead of NAD27/NGVD29. If I try to use geoid12B(conus) it changes my heights to NAVD88. It seems like I'm just missing the proper geoid (I think clarke1866 ?) LS+ Running J-Field 3.0.9.439.

It does appear that if I change to the "?" NAD27/NGVD29 coordinate system AFTER the project is created with WGS84(ITRF2008), it allows me to change the coordinates, but I haven't tested that in the field.
Could you share the project please?
 

APADDEN07

Member
Uploading to support now. LS+ 00998 Project: WE-07-166-2 SP 11-20-20.

The issue I brought up was with creating ANY job in 27/29, but this particular job is one that's giving me issues as well.

To my knowledge it's in NAD27 with ellipsoid heights, because the other system wouldn't work and I don't need elevations on this job (I need it in 27 for old state highway and railroad takings). This particular file does not produce a DPOS report once the points have been processed, and for some reason the autonomous coordinates are N -2.087 / E 1.241 ... despite the base startup screenshot showing them in NAD27.
 

APADDEN07

Member
Nope. Started from autonomous base position.

20201120-10.39.56_6201.png
 

Vladimir Prasolov

Well-Known Member
JAVAD GNSS
Uploading to support now. LS+ 00998 Project: WE-07-166-2 SP 11-20-20.

The issue I brought up was with creating ANY job in 27/29, but this particular job is one that's giving me issues as well.

To my knowledge it's in NAD27 with ellipsoid heights, because the other system wouldn't work and I don't need elevations on this job (I need it in 27 for old state highway and railroad takings). This particular file does not produce a DPOS report once the points have been processed, and for some reason the autonomous coordinates are N -2.087 / E 1.241 ... despite the base startup screenshot showing them in NAD27.
You absolutely right. "The datum was not mean sea level, the geoid, or any other equipotential surface. Therefore, it was renamed in 1973, the National Geodetic Vertical Datum of 1929. (Geodetic Glossary, p. 56) " But there is VERTCON interpolation grids between NGVD 29 and NAVD 88. Our GeoData library supports VERTCON 2 files and those files are included in GeoData distribution. I will look how to use that functionality in Triumph-LS. Even if it is not implemented now? we will add it in the next GeoData release. Have a good day.
 

Bryan Enfinger

Active Member
Why not carry elevations all the time ? It's just as easy to carry heights as it is not to. Doesn't matter what vertical datum it is, though NAVD88 would be the preferred datum. You can translate the data back in the office to whatever you want. One day, you'll probably wish you would have determined elevations... just a thought.
 

Matt Johnson

Well-Known Member
5PLS
Do I unterstand correctly that a local system (like 1000, 2000, 500) as base coords will produce less precise measurements by the rover?
I am talking about the WGS84/NAD83 coordinates being broadcast by the base, not local coordinates that are transformed from WGS84 to local and displayed in J-Field. If you set the base to broadcast WGS84/NAD83 coordinates of 1000 , 2000, 500 you will never get a fixed solution with it being so far off.
 

APADDEN07

Member
As an update, and maybe some help/a reminder for myself in the future...

DO NOT USE NAD27/NGVD29 in a project in Jfield. It DOES NOT WORK. Just localize as if it were a local coordinate system, and check an existing Benchmark/NGS station to verify coordinates/elevation in 27/29.

20210928-12.10.05_00998_Coordinate_Systems.png
20210928-13.17.26_00998_3_STAKE.png
20210928-14.22.32_00998_Select_Point_Coordinates.png


Not sure why this doesn't work, SurvCE allows you to use the older datum, I'm guessing it's the newer satellite constellations not being backward compatible, but it seems like there should still be some kind of transformation to convert onboard in the LS+.
 

Vladimir Prasolov

Well-Known Member
JAVAD GNSS
As an update, and maybe some help/a reminder for myself in the future...

DO NOT USE NAD27/NGVD29 in a project in Jfield. It DOES NOT WORK. Just localize as if it were a local coordinate system, and check an existing Benchmark/NGS station to verify coordinates/elevation in 27/29.

View attachment 11956View attachment 11957View attachment 11958

Not sure why this doesn't work, SurvCE allows you to use the older datum, I'm guessing it's the newer satellite constellations not being backward compatible, but it seems like there should still be some kind of transformation to convert onboard in the LS+.
Dear Aaron,
Sorry, I'm on vacation now. I will fix the issue next week.
Best Regards,
Vladimir
 
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