Hi!
Just a wild guess (didn't try), but what if you rendered your map in an
equal area projection (e.g. Mollweide) and reprojected the resulting
raster image - in a second step - to equirectangular (for example using
GDAL)? That could result in something more towards your objective...
Cheers,
Martin
Christopher Stevens <[email protected]>:
Hello Dane,
Thanks for taking a look. So far I can produce an EPSG:4326 image nicely,
your comment boosted that setup (thanks!). This one is quick and ugly,
but
should work for illustration purposes:
http://www.flickr.com/photos/8139783@N08/9309514743/
Now to add some basic large labels:
http://www.flickr.com/photos/8139783@N08/9309518499/in/photostream/
If I then project this on a sphere (virtual one in this example, but
looks
the same in real projection), the geography placement looks great and
lines
up well with other datasets. The styling gets odd with labels and lines
getting thinner horizontally.
http://www.flickr.com/photos/8139783@N08/9309514621/in/photostream/ -
side
view
http://www.flickr.com/photos/8139783@N08/9309514685/in/photostream/ -
pole
view, the presenter often turns the globe this way for audience
Let me know if that helps illustrate the challenge better.
Thanks again,
Chris
On Wed, Jul 17, 2013 at 11:41 AM, Dane Springmeyer <[email protected]>
wrote:
Chris,
It would be helpful to explain what you've tried already. Mapnik
supports
proj4 and proj4 understands quite a few projections. I'm no expert in
equirectangular projections but
https://en.wikipedia.org/wiki/Equirectangular_projection states that
this
is basically a term for the well know set of lon/lat based geographic
coordinate systems.
So, can you try simply changing your Mapnik Map `srs` value to EPSG:4326
or a specific Equidistant cylindrical projection like
http://spatialreference.org/ref/epsg/3786/
The specific Mapnik Map XML syntax can be found by following the link
for
"Mapnik XML" like:
http://spatialreference.org/ref/epsg/3786/mapnik/
Dane
On Jul 17, 2013, at 9:41 AM, Christopher Stevens <
[email protected]> wrote:
Hello gurus,
I'm thinking that I may need to find some alternative data visualization
software to make this work, but I love mapnik and thought it would be
good
to start here first.
I'm hoping to create a basic themed map of different types of data and
plot it on a full-Earth image (I can figure this part out, starter
examples
cover this as well). The challenge is that I'm then projecting this on
Science
On a
Sphere<http://www.spacefoundation.org/visit/northrop-grumman-science-center-featuring-science-sphere/science-sphere%C2%AE>,
which requires equirectangular images that distort more towards the
poles.
Here's a quick example of something I made in a 3D program to show
latitude
and longitude lines (note how the lines and labels get fuzzy and
stretched
near the poles).
http://www.flickr.com/photos/8139783@N08/9305646391/
Is there a way to add this type of distortion in mapnik? I'm guessing
not
as mapnik is optimized for other uses (but who knows). I'm guessing
that it
would "work" as is, but labels would get distorted (there are
work-arounds), and lines would get very thin near the poles.
Thanks for the feedback in advance. Let me know if I can answer any
questions.
Best regards,
Chris
_______________________________________________
dev mailing list
[email protected]
http://lists.openstreetmap.org/listinfo/dev
