[Marble-bugs] [marble] [Bug 350105] Incorrect Flat Map representation

[David G Dawson]

https://bugs.kde.org/show_bug.cgi?id=350105

--- Comment #5 from David G Dawson <smokey9s at bigpond.com> ---
Hello Dennis,
Thankyou for responding.
Not going to be happy with any of those until I see a translation from 
yout Marble Globe onto a flat surface.
The compression at the North Pole is most unreal as is the stretching 
distotion at the South.
Have never agreed with a Gall-Peters due to the distortions involved 
unless someone can explain why it needs to be distorted from what I can 
see on my 15" Globe I have here.
This will always be a problem until someone flattens out the Globe 
correctly and will be a first.
I am not bad at CAD but in electronics and will have a go but this needs 
to be done and done correctly maintaining all relevant relationships 
with respect to true sizes.

There are several problems here in that we are not really sure just how 
much NASA is hiding from us in a true picture of the Earth Globe as 
taken from Space.
Secondly we have a problem in that engineers do not consider any 
curvature calculations when they decide to build a subway under a city 
and I am asking WHY?
This applies to roads and railways and mountain tunnels as well etc.
Thirdly I am rain engineering here and have also found that there is no 
curvature to the Earth as my magnetic long distance directional pointing 
is some 10º astray.
The Australian Bureau Of Meteorology has failed to respond to my letter 
on this question of 'no curvature'.
Can you translate your Marble Globe onto a flat surface, maintaining 
correct size relationships?
Thankyou.

David G

On 12/07/2015 8:45 AM, Dennis Nienhüser wrote:
> https://bugs.kde.org/show_bug.cgi?id=350105
>
> Dennis Nienhüser <nienhueser at kde.org> changed:
>
>             What    |Removed                     |Added
> ----------------------------------------------------------------------------
>               Status|UNCONFIRMED                 |NEEDSINFO
>           Resolution|---                         |WAITINGFORINFO
>                   CC|                            |nienhueser at kde.org
>
> --- Comment #4 from Dennis Nienhüser <nienhueser at kde.org> ---
> >From Google Earth Help: "What is a Map Projection? A map projection is a
> mathematical expression that is used to represent the round, 3D surface of the
> earth on a flat, 2D map. This process always results in distortion to one or
> more map properties, such as area, scale, shape, or direction. Because of this,
> hundreds of projections have been developed in order to accurately represent a
> particular map element or to best suit a particular type of map."
>
> The flat map and mercator projections available in Marble are not supposed to
> preserve area measure.
>
> You might be looking for a projection from
> https://en.m.wikipedia.org/wiki/Cylindrical_equal-area_projection
> There is a (not yet finished) patch at
> https://git.reviewboard.kde.org/r/123538/ which implements the Gall-Peters
>
> projection, see https://en.m.wikipedia.org/wiki/Gall–Peters_projection . Maybe
> you're looking for that one?
>

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