1 Reply Latest reply on Aug 3, 2010 3:12 PM by MKennedy-esristaff

    Reprojecting State Plane & GCS_GRS_1980 to WGS_1984_Web_Mercator_Auxiliary_Sphere

    brianddurham
      We are attempting to reproject several raster and vector datasets from GCS_GRS_1980 to WGS_1984_Web_Mercator_Auxiliary_Sphere.  I have tried a several different transformations but each time there is a noticeable shift in the data.  Does anyone know the correct transformation to use?  Our data is mostly in the SE United States, mainly Georgia, South Carolina, & North Carolina.  We also have a few datasets that span the entire USA.

      I'm having the same problem determining the correct transformation from state plane (GA FT, SC Int FT, & NC FT) to web mercator.  Any ideas?

      Thank you very much in advance!
      Brian
        • Re: Reprojecting State Plane & GCS_GRS_1980 to WGS_1984_Web_Mercator_Auxiliary_Sphere
          MKennedy-esristaff
          We are attempting to reproject several raster and vector datasets from GCS_GRS_1980 to WGS_1984_Web_Mercator_Auxiliary_Sphere.  I have tried a several different transformations but each time there is a noticeable shift in the data.  Does anyone know the correct transformation to use?  Our data is mostly in the SE United States, mainly Georgia, South Carolina, & North Carolina.  We also have a few datasets that span the entire USA.

          I'm having the same problem determining the correct transformation from state plane (GA FT, SC Int FT, & NC FT) to web mercator.  Any ideas?

          Thank you very much in advance!
          Brian


          Hi Brian,

          I assume, because they're state plane, that the geographic coordinate systems are either NAD 1983 or NAD 1983 HARN (or both). Any NAD83 / WGS84 transformation should do minimal to no shifting, depending on which one is used. At worst, in that part of the country, they should differ by no more than a meter. Are you seeing shifts larger than that?

          NAD_1983_To_WGS_1984_1 is a null transformation (parameters are zeroes). It assumes NAD 1983 and WGS 1984 are equivalent. That isn't true any more, so a more current transformation, NAD_1983_To_WGS_1984_5, does try to compensate for the current differences.

          NAD_1983_HARN_To_WGS_1984 is another null transformation.
          WGS_1984_(ITRF00)_To_NAD_1983_HARN is similar to NAD_1983_To_WGS_1984_5.

          Melita