Thanks Oliver ! Now I know what I do when I change the latitude of true scale of a Mercator-projected map.
+k_0 works fine too, and is easier to catch. I use +k_0=0.5. Bye ! Le 13/12/2015 15:27, Oliver Eichler a écrit : > 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 --- 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
