[Qgis-user] How to display a scale bar in km on a map in degrees?

[Cascafico Giovanni]

Should't be enough plotting in UTM with grid and overlying also Latlong
grid?
Il giorno 16/apr/2013 15.46, "Carlos Cerdán" <sig.upagu at gmail.com> ha
scritto:

> Hi Barend:
>
> You're right, Lat-long maps are just a plane representation of another
> representation of Earth as an ellipsoid and fails on poles.
>
>    > why not use UTM or another projection to start with?
>
> Because some times we need simple maps, for example touristic maps of
> small areas where you can forgot the ellipsoid and take Earth as plane.
> Examples here:
>
> - http://www.rumbosonline.com/images/issue13/13-64-map.jpg
> -
> http://www.kuelapadventure.com/spanish/index.php/tips-de-viajero/mapa-turistico-chachapoyas
>
> A Lat-long grid would be useful to locate any place of these maps in
> Google Earth but it's missed on both of them.
>
> An UTM grid not always is a complete help. For example Where is the place
> of next map: http://dynacorgold.com/en/casaden-overview-map-casaden.php
>   ?  You have 60 options if you don't know what UTM zone is it.
>
> If this is not sufficient for you... well I'll be wrong but I find useful
> this kind of maps.
>
> Thanks for the dissertation
>
> Carlos
>
>
>
>
> 2013/4/16 <b.j.kobben at utwente.nl>
>
>> Dear Carlos,
>>
>> I understand that you think the combination is useful, but my point is
>> actually that the scale bar is NOT useful because it is plain wrong, it
>> does not even approximate distances in many places in the map! Try
>> wrapping you head around the fact that the North Pole (a single point of
>> length 0 km) is actually shown as a line of the same length as the equator
>> (40075 km), and you see how wrong your "approximate" distances can be....!
>>
>>
>> And you do not answer my question: why not use UTM or another projection
>> to start with? Latlon SEEMS simple, but many casual users fail to
>> understand that they are actually looking at angles from the center of a
>> Globe, plotted as if they are XY-coordinates on plain.
>>
>>
>> And do not worry, your english is fine!
>>
>> Barend
>>
>> On 15-04-13 22:17, "Carlos Cerdán" <sig.upagu at gmail.com> wrote:
>>
>> >
>> >
>> >
>> >2013/4/15 <b.j.kobben at utwente.nl>
>> >
>> >Hi there,
>> >
>> >I appreciate the clever tip for having a km scale bar on a lat-long maop,
>> >but as a cartogra[her I must protest, because the scale bar is of course
>> >mostly nonsensical. The differences in distances between the two
>> (mercator
>> >projected UTM and non-projected degrees) can potentially be huge. The
>> >scale bar therefore cant be grossly wrong...
>> >
>> >
>> >
>> >Ajá.. As a simple user I find useful a scale bar to measure approximate
>> >distances on a lat-long map.
>> >
>> >If you have your map in UTM, why not print that one with the proper scale
>> >bar? The question to the original poster therefore would be: why do you
>> >feel the need to have a map in degrees, why not use one that is projected
>> >and where km is the proper scale-bar...?
>> >
>> >
>> >
>> >
>> >In the same sense: If you want  to show the location of a place on Earth
>> >to not GIS skills people, Lat-Long is useful for a first reading location
>> >and scale bar to measure approximate distances ... so Why no use that
>> >combination?
>> >
>> >
>> >
>> >Developers please fix an issue (Correct me if it's not an issue):
>> >when you have two or more maps in a compositor and the scale bar is
>> >related to map 1 (or more), and you close your file, next time you open
>> >it, scale bar is related to Map 0 and you have to select Map 1 again.
>> >(QGIS 1.8 - Ubuntu 12.04).
>> >
>> >
>> >Carlos Cerdán
>> >
>> >
>> >
>> >PD Sorry if my English is bad.
>> >
>> >
>> >
>> >
>> >
>>
>>
>
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