A further suggestion, which may be too much.
UTM, and the various LCC used in the US at State Plane Coordinate
Systems, have x/y coordinates that are nominally in meters (well, the
older ones used ft or ftUS). Central meridian or standard parallel
scale factors are chosen to make distance measur
Nyall Dawson writes:
> I've been thinking about introducing a new warning when exporting
> layouts, which would look something like this:
>
> 1. For each scale bar, look at the referenced map
> 2. Measure the scale using multiple lines, each across the
> top/middle/bottom horizontally and left/c
Hi,
Thanks to Greg, Patrick, Nicolas and Nyall for the good discussion.
I never used lat/lon based layouts before and the result can be odd. I
was trying to make it work, but it is not easy. The layout must include
a warning about the difference in scales along the axes.
As Nyall said, addit
Hi Nyall,
That would be a "nice to have"!
Nicolas
On 2022-04-06 9:13 p.m., Nyall Dawson via Qgis-user wrote:
On Thu, 7 Apr 2022 at 10:26, Greg Troxel wrote:
Nyall Dawson writes:
In all cases (projected OR geographic) the scalebar logic is:
1. Create a horizontal line across the width of
On Thu, 7 Apr 2022 at 10:26, Greg Troxel wrote:
>
>
> Nyall Dawson writes:
>
> > In all cases (projected OR geographic) the scalebar logic is:
> >
> > 1. Create a horizontal line across the width of the layout map
> > 2. Calculate the length of that line using great circle/ellipsoidal
> > calcula
Nyall Dawson writes:
> In all cases (projected OR geographic) the scalebar logic is:
>
> 1. Create a horizontal line across the width of the layout map
> 2. Calculate the length of that line using great circle/ellipsoidal
> calculations, based on the project's ellipsoid settings.
> 3. Compare th
On Wed, 6 Apr 2022 at 09:34, Greg Troxel via Qgis-user
wrote:
>
> Jorge Gustavo Rocha via Qgis-user writes:
>
> > I need you help to understand how scale works with geographic
> > coordinate systems.
In all cases (projected OR geographic) the scalebar logic is:
1. Create a horizontal line acro
Hi,
Your calculations are based on a sphere. The different crs use a geoids. It
would help if you could say what crs you are using and the differences between
what you get and what you expect.
Nicolas Cadieux
https://gitlab.com/njacadieux
> Le 6 avr. 2022 à 13:13, Jorge Gustavo Rocha via Qgis-
Hi,
Thank you all for the comments.
As far as I can see from my tests, the behavior is not related with the
CRS in use. I've used more than one meter based projection to make sure
the areas were fine. I use the advanced digitizing tools to create
segments with the exact distance. Using projec
Patrick Dunford via Qgis-user writes:
> On 6/04/22 11:34, Greg Troxel via Qgis-user wrote:
>> Jorge Gustavo Rocha via Qgis-user writes:
>>
>> 2) Using a geographic CRS, the same 150mm x 150mm map, at the same
>>> 1:1 scale, the area is bigger then the 1500m polygon. The result
>>> is attach
Hi,
Great question! I am not the best person to answer it as this is a question
for the Proj4 project people. They do geodesy and generally, a conversation
with them bring me back to my worse math class experiences! I should have
listened, I say to myself!
Anyways, CRS are not all created th
On 6/04/22 11:34, Greg Troxel via Qgis-user wrote:
Jorge Gustavo Rocha via Qgis-user writes:
2) Using a geographic CRS, the same 150mm x 150mm map, at the same
1:1 scale, the area is bigger then the 1500m polygon. The result
is attached https://nextcloud.geomaster.pt/index.php/s/H2eAytsPAN
Jorge Gustavo Rocha via Qgis-user writes:
> I need you help to understand how scale works with geographic
> coordinate systems.
A good question.
> This is my use case:
It seems like your minimal example to show what doesn't work like you
think it should, instead of what you want to do, but tha
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