Hi Matthias,
probably this is academical...
Am 24.06.2014 10:42, schrieb Matthias Kuhn:
Hi Bernhard,
I wouldn't say no sense at all. It strongly depends on the context, but
if you have for example a lesson for geography students and are
introducing CRS/projections and their properties one could want to add a
scale bar in degrees.
But would that scalebar show the degrees for lon or lat?
If the first (lon) for which latitude?
Either of the two: how do you want to tell people that this scalebar is
only true for North-South (lat) or East-West (lon) measurements and must
not be used in any other direction? IMHO a scale bar is to enable
readers to use their ruler to measure a distance on the map in _any_
direction.
I agree that it's not very common and most people
are probably unused, but if you explicitly state the fact that the map
is in degrees you might even avoid confusion and prevent people from
trying to compare distances.
But adding a scale bar encourages users to compare distances! The fact
that a map is suitable to measure and compare distances is not decided
by the map units but by the used projection and the covered area. If
your map is in degrees just enable the graticules and (if useful) add a
scalebar in m/km/miles (does that work with degrees? I have not tried.
If not this would be a feature request.)
BTW: for which point of a map is the scale bar currently created
(thinking of non-distance-true projections and large areas e.g. continents)?
regards
Bernhard
Best,
Matthias
On 24.06.2014 10:24, Bernhard Ströbl wrote:
Hi,
IMHO a scale bar in degrees doesn't make sense at all apart from being
unused to readers of the map. Because one degree in latitude is always
(uhmm if I recall correctly) 110 km, in longitude this is only true
for the equator, the closer you get to the poles the less km per
degree in longitude (until 0 at the pole itself). If you display only
a small part of the earth you migth manage with two scale bars
(lon/lat) but how would you imagine a scale bar for e.g. north America?
Bernhard
Am 24.06.2014 10:07, schrieb Jorge Tornero - Listas:
Hi, Ted, Matthias and all,
If you enable CRS transform on-the-fly, meter/feet/NM scales can be
shown in WGS84 projects.
About what Matthias said in
Concerning the scale-bar issue. I think, that one should always be
allowed to show a scale-bar, but that the units need to match with the
one in the projection, so in the case of WGS84, the units should be
degrees.
In my opinion, despite this is completely true from a formal point of
view, sometimes you need scales in 'real world' units just to make
possible for people to understand your maps. For the most of the people
I know that see my little work it makes no sense a scale in degrees (in
fact, they could have it in the grid labels) but a scale in nautical
miles (or whatever) makes sense inmediatly for them, even if it is not
accurate. So, providing that the person who is making the map should
know what he/she is doing, it is nice for the user to have the
possibility to show the scale in whatever units he wants. Maybe it could
be corrected just using a projection (I guess that's the proper way),
but sometimes it leads to "weird" (in the sense of people is used to see
*their geography* in a determinate way) maps which somehow annoy people.
All the best,
Jorge Tornero
El 24/06/14 08:59, Matthias Kuhn escribió:
Hi Ted,
I don't get a crash here (Linux/latest prerelease). It would be much
appreciated if you could follow Richards advice for testing/reporting.
Concerning the scale-bar issue. I think, that one should always be
allowed to show a scale-bar, but that the units need to match with the
one in the projection, so in the case of WGS84, the units should be
degrees.
Regards,
Matthias
On 24.06.2014 08:29, Richard Duivenvoorde wrote:
Hi Ted,
I'm not on Win, but if possible can you test this with latest release
candidates, see
http://qgis.org/en/site/getinvolved/development/index.html#location-of-prereleases-nightly-builds
and if that one is crashing, please file an issue:
http://qgis.org/en/site/getinvolved/development/index.html#bugs-features-and-issues
Current dev version has a lot of changes under the hood, but also an
awfull lot of fixes!
So please test the latest version and let us know if that crashes also
Regards,
Richard Duivenvoorde
On 24-06-14 01:30, Ted wrote:
forgot,
using Windows OS
Win 7 Professional x64
Thanks
Ted
On Tue, Jun 24, 2014 at 7:27 AM, Ted <tiruchirapa...@gmail.com
<mailto:tiruchirapa...@gmail.com>> wrote:
Hi Developers
Encountered a very serious problem, looks like this issue is
there
in 2.x
Ways to reproduce;
1. Add a world boundary shp file in wgs84 (you can use other
files too)
http://thematicmapping.org/downloads/world_borders.php
2. Open the print composer, add a new map
3. add scale bar
4. close the composer, return back
5 remove the layer from layer list
6. boom, qgis crash
hope you can fix this soon, thanks
The scale bar issue
1. When a file is degree (wgs84), the scale-bar in print
composer is
useless since its trying to use the map unit.
2. Its logical that, in map composer its always linear map
unit as
in meter, feet, km, etc
3. using qgis in schools and this pose a serious issue, since
the
users dont understand projection etc.
4. the expected behavior is, immaterial of underlying
projection the
scale-bar should have the option to use linear map unit,
specially
meters, km, mile
5. read in stackexchange, this is a known issue. hope the dev
community can help to fix this one.
thanks a lot.
hurt my fingers, not able to type proper :(
cheers
ted
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