AnsweredAssumed Answered

Issues with WGS_1984_(ITRF00)_To_NAD_1983 Datum transformation

Question asked by jdeloretta_rettew on Dec 10, 2018
Latest reply on Jun 17, 2019 by mitchj_madsewer

Hi,  

 

Recently been having issues while working with this datum transformation.  My company is working on a project where data comes from Trimble GPS receivers and also survey data.  The survey data is both exported from Trimble Business center and also transformed with PostGIS using Proj4 into local state plane coordinates.  The GPS data is post-processed with Trimble Pathfinder office and exported as shapefiles into the local state plane coordinate system.  The shapefiles are then imported into our SDE which is in WGS84 using the WGS_1984_(ITRF00)_To_NAD_1983 Datum transformation. 

 

When comparing data exported from PostGIS to the data in our SDE they line up fine in ArcMap, until I apply the WGS_1984_(ITRF00)_To_NAD_1983 Datum transformation to my map document (ArcMap 10.5). We see a 1m shift between the datasets when the datum transformation is applied.

 

It appears that there is no datum transformation applied to the survey data that is transformed using PostGIS/Proj4.  Digging deeper I found that between WGS84 and NAD83 there is essentially no difference between the two- at least the original iteration of WGS84 and NAD83.  Going even further, I confirmed in Pathfinder Office that there is no transformation between WGS84 and NAD83 (see attachment) .  I noticed that the transformation values applied in ArcGIS using WGS84 using the WGS_1984_(ITRF00)_To_NAD_1983 match the transformation values exactly to what Trimble Pathfinder office uses for NAD 1983 (Conus) CORS96 (see attachments). 

 

It is at this point where I am questioning everything I know about datums and coordinate systems.

 

 

Does anyone have any input on this workflow? Should Survey be exporting using a transformation in Trimble Business Center/Proj4 or should I ignore the datum transformation?

 

Any input or clarification would be greatly appreciated, I've run myself into an infinite loop.

Outcomes