Hi
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.
Matthias
Matthias,
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?
Thanks,
Ben Root
On Wed, Nov 17, 2010 at 5:45 AM, Matthias Plum <plum@…669…> wrote:
Hi
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.
Matthias
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.
Ben Root
hammer.patch (620 Bytes)
On Wed, Nov 17, 2010 at 8:44 AM, Benjamin Root <ben.root@…1304…> wrote:
On Wed, Nov 17, 2010 at 5:45 AM, Matthias Plum <plum@…669…> wrote:
Hi
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.
Matthias
Matthias,
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?
Thanks,
Ben Root
Dear all,
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
http://www.progonos.com/furuti/MapProj/Dither/CartHow/HowAiHaW3/howAiHaW3.html
or
The Glossary of Mapping Sciences 1994,
Best regards,
Tobias
On Wednesday 17 November 2010 Benjamin Root wrote:
--
Tobias Winchen
III. Physikalisches Institut A
RWTH Aachen University
+49 (0)241 80 27326
Tobias and Matthias, thanks for the confirmation. I have updated the maintenance branch and the trunk with revisions 8808 and 8809.
Ben Root
On Mon, Nov 22, 2010 at 6:59 AM, Tobias Winchen <winchen@…2509…> wrote:
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
http://www.progonos.com/furuti/MapProj/Dither/CartHow/HowAiHaW3/howAiHaW3.html
or
The Glossary of Mapping Sciences 1994,
Best regards,
Tobias