<div dir="ltr">Hello,<div><br></div><div>I am quite new to the use of  Proj4. I spend a few days to investigate a problem but I have no clue how to solve it. So that's why I am writing to you.  I hope you will be able to answer me.</div><div><br></div><div>I have 2 different <span class="" id=":18k.22" tabindex="-1" style="">CRS</span> for the same planet : one is based on<span style="background-color:rgb(250,210,207)"> the sphere</span> (CRS1, radius=<span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">3396190</span>) and another one based on the ellipse (CRS2, <span style="font-size:small;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">a=</span><span style="font-size:small;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">3396190 b=3376200</span>). When I give the (longitude, latitude) in the CRS1 as inputs (<span class="" id=":18k.27" tabindex="-1" style="">planetocentric</span> <span style="background-color:rgb(250,210,207)">latitude = planetographic</span> latitude), I want to get the <span class="" id=":18k.31" tabindex="-1" style="">planetographic</span> latitude expressed in the CRS2. So, I wrote the following command :</div><div>cs2cs +<span class="" id=":18k.32" tabindex="-1" style="">proj</span>=<span class="" id=":18k.33" tabindex="-1" style="">latlong</span> +a=3396190 +b<span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">=</span><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">3396190 +to <span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">+<span class="" id=":18k.34" tabindex="-1" style="">proj</span>=<span class="" id=":18k.35" tabindex="-1" style="">latlong</span> +a=</span><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">3396190 +b=3376200</span></span><br></div><div><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">> 0 80  # longitude latitude</span></span></div><div><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></span></div><div>I get the following result "0dE<span style="white-space:pre">        </span>80dN 0.000" . The latitude should change but it is not the case !!! Should I add some options ?  Is it possible to do this kind of transformation with proj4 ?</div><div><br></div><div>Thanks in advance,</div><div>Jean-Christophe</div></div>