Hi Jorge On 24.06.2014 14:34, Jorge Tornero - Listas wrote: > Hello All, > > El 24/06/14 14:02, Matthias Kuhn escribió: >> Doesn't really make sense to me. Graticules are just another >> reference for distances (in degrees in this case) and an alternative >> or addition to scale bars. What problem exactly would the combination >> of a grid in degrees and a scalebar in meters solve? > > Well, you should try to think about people which may receive > positioning info in degrees but need to judge distances in "real > world" units: on ships, for instance (sorry but that's my > bussiness...). And remember, always taking into account that the area > should be relatively small. ... and close enough to the equator to have no horizontal/vertical length mismatch problems. In this case (comparing distances in real-world units) another projection should actually be preferred. Putting the degrees-grid on top of that in turn sounds very sensible. > > Grid in degrees --> Fast positioning in the map. > Scale in whichever units but degrees --> Fast estimation of distances, > travel times, speeds. > > Of course you shouldn't trust this kinds of map to navigate... but for > practical uses (survey planning (up to some extent), quick info, > simple illustration) they are OK and appreciated. > >> No idea.But if there should be proper support for scalebars in meters >> on degree-based maps, then it has to be configurable. And also the >> two different scalebars (horizontal vs. vertical) that you mentioned. >> Then it could be that there is a small enough area that this can be >> considered accurate enough to be useful. And there should be warnings >> to inform the mapper that he might be misleading readers and should >> consider to reproject. > > To tell you the truth, in the actual state of the scalebar, all this > is sort of tricky. It would be great to have it properly implemented, > as you suggest. But maybe this maps are seldom used by the majority of > QGIS users and it is not worth the effort and it may perfectly stay as > a trick.
Thinking about it. A warning for unsuitable scale bars would be a nice feature. That could be the shown if the scale varies by more than a certain threshold over the map. I expect that this would help a lot of people to even be aware of the risk involved when choosing projections and to make a conscious decision. Regards, Matthias _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
