[Qgis-developer] QGIS Crash - Serious problem in 2x
Jorge Tornero - Listas
jtorlistas at gmail.com
Tue Jun 24 03:45:49 PDT 2014
Hello all,
Sorry Matthias I didn't replied properly before to the list, I guess you
have seen my message later in the list.
Anyway, my point about this is just:
Is QGIS able to add a scalebar to a map in the units "academically
correct"? It looks like the answer is 'yes' --> COOL!!
Is QGIS able to add a scalebar to a map in **whatever unit** the user
(of QGIS) wants to, for reasons X, Y or Z? The answer seems also to be
'yes' --> COOL!!
is QGIS Composer scalebar improveable in many ways? Certainly!!
Look, maybe a nice improvement is make a real **whatever unit** work!!!
I mean not just meters, feet, NM but also user-defined units. This would
be nice for those who use QGIS for astronomy-related work, for instance,
or as micro-GIS... Same should be appliable for mesaurement... just
dreaming a little...
And, answering to Bernhard about
> 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?
Yes, you can do it (wgs and CRS on the fly on): See the picture in
https://twitter.com/imasdemase/status/479189061975162880/photo/1
(Sorry I uploaded it to flickr and QGIS showcase but don't know why it
doesn't show at all)
Best regards,
Jorge Tornero
El 24/06/14 11:06, Bernhard Ströbl escribió:
> 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 <tiruchirapalli at gmail.com
>>>>>>> <mailto:tiruchirapalli at 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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