topic Re: EGM96 Transformation - Ambiguous error on the help web page in Data Management Questions https://community.esri.com/t5/data-management-questions/egm96-transformation-ambiguous-error-on-the-help/m-p/639250#M36172 <HTML><HEAD></HEAD><BODY><SPAN>The first equation, </SPAN><BR /><BR /><SPAN>h = H + N</SPAN><BR /><BR /><SPAN>is correct which means the second is not. It should be:</SPAN><BR /><BR /><SPAN>H = h - N</SPAN><BR /><BR /><SPAN>My references include Wolfgang Torge's Geodesy, 2nd Edition and </SPAN><A href="http://www.ngs.noaa.gov/GEOID/IMAGES/d05.jpg">National Geodetic Survey</A><SPAN>. I've sent an email to a colleague on the raster team. </SPAN><BR /><BR /><SPAN>Melita</SPAN></BODY></HTML> Wed, 31 Oct 2012 15:22:59 GMT MelitaKennedy 2012-10-31T15:22:59Z EGM96 Transformation - Ambiguous error on the help web page https://community.esri.com/t5/data-management-questions/egm96-transformation-ambiguous-error-on-the-help/m-p/639249#M36171 <HTML><HEAD></HEAD><BODY><SPAN>I am doing some conversions from ellipsoidal to geoid heights and was referring to the help page </SPAN><A href="http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009t000001vm000000">http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009t000001vm000000</A><SPAN> (Converting from orthometric to ellipsoidal heights).</SPAN><BR /><BR /><SPAN>The problem is that the equation </SPAN><BR /><BR /><SPAN>h = H + N</SPAN><BR /><BR /><SPAN>Where</SPAN><BR /><SPAN>h = ellipsoidal height</SPAN><BR /><SPAN>H = orthometric (geoid) height</SPAN><BR /><SPAN>N = geoidal separation</SPAN><BR /><BR /><BR /><SPAN>is restated further down the page as&nbsp; </SPAN><BR /><BR /><SPAN>H = N - h </SPAN><BR /><BR /><SPAN>which is not equivalent.</SPAN><BR /><BR /><SPAN>Which equation is correct? I suspect that the first equation is correct but would prefer to have some independent confirmation of this as opposed to assuming. Thanks in advance.</SPAN></BODY></HTML> Wed, 31 Oct 2012 13:18:39 GMT https://community.esri.com/t5/data-management-questions/egm96-transformation-ambiguous-error-on-the-help/m-p/639249#M36171 GeordieHobart 2012-10-31T13:18:39Z Re: EGM96 Transformation - Ambiguous error on the help web page https://community.esri.com/t5/data-management-questions/egm96-transformation-ambiguous-error-on-the-help/m-p/639250#M36172 <HTML><HEAD></HEAD><BODY><SPAN>The first equation, </SPAN><BR /><BR /><SPAN>h = H + N</SPAN><BR /><BR /><SPAN>is correct which means the second is not. It should be:</SPAN><BR /><BR /><SPAN>H = h - N</SPAN><BR /><BR /><SPAN>My references include Wolfgang Torge's Geodesy, 2nd Edition and </SPAN><A href="http://www.ngs.noaa.gov/GEOID/IMAGES/d05.jpg">National Geodetic Survey</A><SPAN>. I've sent an email to a colleague on the raster team. </SPAN><BR /><BR /><SPAN>Melita</SPAN></BODY></HTML> Wed, 31 Oct 2012 15:22:59 GMT https://community.esri.com/t5/data-management-questions/egm96-transformation-ambiguous-error-on-the-help/m-p/639250#M36172 MelitaKennedy 2012-10-31T15:22:59Z