I am trying to plot data on the sphere and use the hammer projection.
The data ploting works fine, but the angular grid isn't shown correctly.
In the attached picture you can see the error(mouse pointer is on the
position 60 E 30 S). Can anyone help me on this subject? Thanks.
On Wed, Nov 17, 2010 at 5:45 AM, Matthias Plum
> I am trying to plot data on the sphere and use the hammer projection.
> The data ploting works fine, but the angular grid isn't shown correctly.
> In the attached picture you can see the error(mouse pointer is on the
> position 60 E 30 S). Can anyone help me on this subject? Thanks.
Looking at the transform equation for Hammer, it looks like there might be a
mistake in the calculation. Can you include the script you used to make
that figure so I can test the fix?
On Mon, Nov 22, 2010 at 6:59 AM, Tobias Winchen <
> Dear all,
> > On Wednesday 17 November 2010 Benjamin Root wrote:
> > Nevermind about the example script, I tested it myself and verified the
> > problem. The fix was simple. We were missing a square root for the
> > denominator of the formula for x and y. Before I submit this patch, can
> > anybody with more knowledge about the hammer projection verify that the
> > equations on the wikipedia page are correct? I would like to verify the
> > transformation before making this change.
> The patch seems correct - see
> The Glossary of Mapping Sciences 1994,
> Best regards,
Tobias and Matthias, thanks for the confirmation. I have updated the
maintenance branch and the trunk with revisions 8808 and 8809.