<div dir="ltr"><div><br clear="all"></div><br><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">I
am trying to project some EPSG:4326 locations (from a GPS) to
EPSG:5677 (DHDN Germany Zone 3). I have sample data from the German road
authorities (BASt). They feel that the locations provided by proj
(9.6.0) are consistently 1.5 meters or so away from that they expect.
They were also expecting a change in altitude as the ellipsoid was
different. I
have implemented this with something like this:</div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">myCRS = proj_create_crs_to_crs( 0, "EPSG:4326", "EPSG:5677", 0);</div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">And then calling proj_trans(myCRS, PJ_FWD, PJ_COORD);</div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">My
question is if I need to do more than this as EPSG:5677 is ellipsoid
Bessel 1841. </div><div style="font-family:Aptos,"Aptos_EmbeddedFont","Aptos_MSFontService",Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"> </div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">Roger Oberholtzer</div></div>