Have a look at the definition of the Mercator projection: https://en.wikipedia.org/wiki/Mercator_projection
And now think about why Mercator projections usually stop somewhere between 80 and 90 °. And what must be the scale of a latitude of true scale getting close to 90°. Btw. there are more parameters to play with: ftp://priede.bf.lu.lv/pub/GIS/koordinatas/PROJ.4/proj4_GenParms.txt Have a look at +k_0 Oliver Am Sunday 13 December 2015, 14:32:20 schrieb zero: > Sorry to bother you again about this topic, > > I played a little bit with +lat_ts but I did not find any simple > explanation about it. > > From what I experienced with QMS : > With +lat_ts = 89 highest detail level is available even when zooming > out quite far but zooming in is quite limited > With +lat_ts = 60 I am happy > > but I am happy and ignorant (I know that knowledge does not always mean > happiness, but I would accept a little more knowledge taking the risk to > be a little less happy :) > > Can you explain a little bit ? > > Thanks a lot > > -------- Message transféré -------- > Sujet : Re: [Qlandkartegt-users] "Detail level" adjustment for Garmin > maps > Date : Sat, 12 Dec 2015 07:38:29 +0100 > De : [email protected] > Pour : [email protected] > > > > Thanks Oliver! > > By adding +lat_ts=xx.x to the projection string (where xx.x is the > current latitude of the displayed place) + by choosing "square" > (optimized for TMS and WTMS tiles) I get even more space than with QLGT. > > The only (minor) drawback is that a grid is visible on hillshading but > this is not a big deal. > > Bye! > > Le 11/12/2015 18:21, OLiver Eichler a écrit : > > QLGT used latitude of true scale (+lat_ts=) in the projection string. > > That's > > why scaling will not match 100%. You can add the lat_ts parameter to > > your > > projection string if you really want to a have a more or less 100% > > match. > > However QLGT does this dynamically for the center point of the loaded > > map. So > > it's a bit of a running target. > > > > But else the scale to bit relation is the same. You can cross check it > > yourself. In QLGT > > > > CMapTDB::scale_t CMapTDB::scales[] = > > > > and in QMS > > > > quint8 CMapIMG::scale2bits(const QPointF& scale) > > > > I checked the levels up to 20 bit. They match. > > > > Am Friday 11 December 2015, 16:34:56 schrieb [email protected]: Hello, > > > > in the previous email setting is "log". > > > > In this attached screenshot it is "square" : it is larger but still not > > as large as QLGT. > > > > Thanks ! > > > > Le 11.12.2015 15:37, Oliver Eichler a écrit : what scale mode do you > > use in View-> Setup Map View ? > > > > Am 11.12.2015 um 14:58 schrieb [email protected]: Hello again, > > > > Same test with QLGT (see attached screenshot) gives the same result : > > it looks like QMS detail level is set one step below QLGT. > > > > My main concern is that with QMS displayed area is smaller. > > > > (other possibilites are to buy a bigger screen or to print my maps : > > that is a big advantage of paper maps : highest detail level is > > available at every zoom level :) ) > > > > Bye > > > > ------------------------------------------------------------------------- > > ----- > > > > _______________________________________________ > > Qlandkartegt-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users > > -------------------------------------------------------------------------- > > ---- _______________________________________________ > > Qlandkartegt-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users > > ---------------------------------------------------------------------------- > -- _______________________________________________ > Qlandkartegt-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users > > > > > > --- > L'absence de virus dans ce courrier électronique a été vérifiée par le > logiciel antivirus Avast. https://www.avast.com/antivirus ------------------------------------------------------------------------------ _______________________________________________ Qlandkartegt-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users
