topic Re: What is the difference between horizontal transformations using the ArcMap Project Tool and NOAA VDatum for transforming WGS84 (ITRF00) to NAD83? Which one is more accurate? in Geoprocessing Questions https://community.esri.com/t5/geoprocessing-questions/what-is-the-difference-between-horizontal/m-p/475365#M15909 <HTML><HEAD></HEAD><BODY><P>If your data's RTK then it's not on NAD 1983. You'll get access to other transformations if you use a later realization like NAD 1983 (2011) or NSRS2007. I would recommend using WGS_1984_(ITRF08)_To_NAD_1983_2011 instead, for instance. </P><P></P><P>Equation-based transformations (coordinate frame, position vector, Molodensky-Badekas, geocentric translations) will also give (slightly) different results if you run them with or without ellipsoidal heights.</P></BODY></HTML> Fri, 01 Jul 2016 21:46:41 GMT MelitaKennedy 2016-07-01T21:46:41Z What is the difference between horizontal transformations using the ArcMap Project Tool and NOAA VDatum for transforming WGS84 (ITRF00) to NAD83? Which one is more accurate? https://community.esri.com/t5/geoprocessing-questions/what-is-the-difference-between-horizontal/m-p/475364#M15908 <HTML><HEAD></HEAD><BODY><P>I've noticed a ~30cm horizontal difference between data that I transformed from WGS84 (ITRF00) to NAD83 using the ArcMap Project Tool and the same points transformed using NOAA's Vertical Datum Transformation Tool (VDatum). Is there a difference in the parameters used in these transformations? Is one more accurate? Or did I do something funky? Unfortunately, this small of an error could make a big difference for my data, which was collected by RTK and should be accurate to ~2cm. I saw that the WGS_1984_(ITRF00)_To_NAD_1983 transformation has an accuracy of 0.10m, which is less accurate than I would like. It seems like the difference between the two should not be more than 3x the published accuracy, so I think I must be missing something. Let me know if you have thoughts on the best transformation method to use. Thank you for your help!!</P></BODY></HTML> Wed, 29 Jun 2016 21:50:32 GMT https://community.esri.com/t5/geoprocessing-questions/what-is-the-difference-between-horizontal/m-p/475364#M15908 KelseyMcDonald 2016-06-29T21:50:32Z Re: What is the difference between horizontal transformations using the ArcMap Project Tool and NOAA VDatum for transforming WGS84 (ITRF00) to NAD83? Which one is more accurate? https://community.esri.com/t5/geoprocessing-questions/what-is-the-difference-between-horizontal/m-p/475365#M15909 <HTML><HEAD></HEAD><BODY><P>If your data's RTK then it's not on NAD 1983. You'll get access to other transformations if you use a later realization like NAD 1983 (2011) or NSRS2007. I would recommend using WGS_1984_(ITRF08)_To_NAD_1983_2011 instead, for instance. </P><P></P><P>Equation-based transformations (coordinate frame, position vector, Molodensky-Badekas, geocentric translations) will also give (slightly) different results if you run them with or without ellipsoidal heights.</P></BODY></HTML> Fri, 01 Jul 2016 21:46:41 GMT https://community.esri.com/t5/geoprocessing-questions/what-is-the-difference-between-horizontal/m-p/475365#M15909 MelitaKennedy 2016-07-01T21:46:41Z