<div>Hi again Pavel,</div><div><br></div><div>the information provided by PROJ is correct, you just need to be aware that most software interpret it in a different way. In fact a cartographic programme like QGis should not portray datasets defined in a geodetical system, and always request an explicit projection. Depending on your goal, it is possibly wiser to use a cartographic system.<br></div><div><br></div><div>Regards.</div><div class="protonmail_signature_block"><div class="protonmail_signature_block-user"><div><br></div><div>-- <br></div><div>Luís Moreira de Sousa<br></div><div>Email: <a href="mailto:luis.de.sousa@protonmail.ch">luis.de.sousa@protonmail.ch</a><br></div><div>RingID: ring:7ca91d83f4f9dec82fec9f1144b8e5c1ef2a110c<br></div><div>URL: <a href="https://ldesousa.github.io">https://ldesousa.github.io</a><br></div></div><div><br></div><div class="protonmail_signature_block-proton">Sent with <a target="_blank" href="https://protonmail.com">ProtonMail</a> Secure Email.<br></div></div><div><br></div><div>‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐<br></div><div> On Sunday, 18 November 2018 23:24, Pavel Hančar <pavel.hancar@gmail.com> wrote:<br></div><div> <br></div><blockquote type="cite" class="protonmail_quote"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><div><div><img data-darkreader-inline-bgcolor="" class="proton-embedded" name=":0" src="https://ssl.gstatic.com/ui/v1/icons/mail/profile_mask2.png" style="background-color: rgb(137, 211, 178); --darkreader-inline-bgcolor:#3c624e;"><br></div></div><div> Hi Luís,<br></div></div><div> Thank you for your answer. The <a href="https://en.m.wikipedia.org/wiki/Equirectangular_projection">linked article</a> says the Marinus of Tyre's projection is also called the equidistant cylindrical projection. It implies, that the 'lonlat' and 'latlong' are just aliases for 'eqc'. Right? In that case I would expect to get this information after I enter<br></div><div>$ proj -l=lonlat<br></div><div>IMHO the output<br></div><div>lonlat : Lat/long (Geodetic) <br></div><div><div>does not say much.<br></div><div><br></div><div>I am just a beginner, so I might be wrong, but a note saying it's an alias for 'eqc' could improve the description listing.<br></div></div><div><br></div><div>Best wishes,<br></div><div> Pavel<br></div></div></div></div><div><br></div><div class="gmail_quote"><div dir="ltr">so 17. 11. 2018 v 23:52 odesílatel Luís Moreira de Sousa <<a href="mailto:luis.de.sousa@protonmail.ch">luis.de.sousa@protonmail.ch</a>> napsal:<br></div><blockquote data-darkreader-inline-border-left="" class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex; --darkreader-inline-border-left:#4c4b49;"><div>Hi Pavel,<br></div><div><br></div><div>that equates to Marinus of Tyre's projection [0]. Even though PROJ itself takes it as a geodetical coordinate system, pretty much all other software (Qgis, GRASS, etc) treats it as cartographic. You should keep this in mind when computing distances or areas in this system.<br></div><div><br></div><div>Regards.<br></div><div><br></div><div>[0] <a href="https://en.m.wikipedia.org/wiki/Plate_carr%C3%A9e_projection" target="_blank">https://en.m.wikipedia.org/wiki/Plate_carr%C3%A9e_projection</a><br></div><div><br></div><div><br></div><div>Sent from ProtonMail mobile<br></div><div><br></div><div><br></div><div><br></div><div>-------- Original Message --------<br></div><div>On 17 Nov 2018, 21:03, Pavel Hančar < <a href="mailto:pavel.hancar@gmail.com" target="_blank">pavel.hancar@gmail.com</a>> wrote:<br></div><blockquote class="m_-9114605361177031736protonmail_quote"><div><br></div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div> Hello,<br></div><div>I
am trying to understand some basic concepts of map rendering, but I've
got really confused by the fact, that "longlat" or "lonlat" are often
mentioned as a name of a projection. For example:<br></div><div>+proj=longlat +datum=WGS84 +no_defs<br></div><div><br></div><div>AFAIK
longitude and latitude stay for a coordination system, not for a map projection. Thus I
thought it was a kind of simplification and the actual projection must have been
the Equidistant Cylindrical. But I found the Equidistant Cylindrical
being determined by "eqc" not "longlat". So what is the "longlat"? I ended up running
`proj -lP`, but found just this:<br></div><div><br></div><div><div>lonlat : Lat/long (Geodetic)<br></div><div>latlon : Lat/long (Geodetic alias)<br></div><div> <br></div></div><div>The
only explanation is, that it is geodetic. But to me it seems it is not
any explanation, but a further specification saying it is not
geocentric, but the angles are taken from normals of the ellipsoid.<br></div><div><br></div><div>So, what projection is the "lonlat"? Or how are longitude and latitude projected to the flat map when nothing else is specified?<br></div><div><br></div><div> Thank you very much.<br></div><div><br></div><div> Best wishes,<br></div><div><div> Pavel Hančar<br></div><div><br></div></div></div></div></div></div></blockquote></blockquote></div></blockquote><div><br></div>