Celestia Forums

Hello people.

Im working on an addon at the moment to show the Earth were it rotated, so that the poles were in different places. For example, the north pole on Malaysia and the south pole on South America, or the north pole on Africa and south pole on Hawaii

What I need is a way to (using the current Earth map) produce rotated versions of them, as if I put them onto a sphere, rotated the sphere, and then unwrapped it again... I hope that makes sense?
Once ive got that ill retexture them so they look realistic and everything

I currently use Anim8or for 3d modelling, Im fairly basic with it. If anyone knows a way to do it in Anim8or, or another good program that I can use to do what I want, that will be brilliant

Thanks

But isn't that a most easy task??

I don't know Anim8or, but every decent image manipulation software (GIMP, Photoshop,...) has the possibility of offsetting textures in cylindrical projection independently in x and y directions.
All you got to do is to activate the switch: /Wrap/ texture. Then you offset the earth texture in latitude (and possibly also in longitude) such that Malaysia becomes equal to the upper border =pole of the offset and wrapped texture. It's a less than 20 second affair.

Bye Fridger

I am going to show my ignorance here. I must admit that I use Photoshop, but I haven't used Gimp yet (I am downloading it now). When you offset in Photoshop it is purely rectangular. The polar regions will not spread out in a rectangular offset as they would need to for Neethis. Is there a plug in that I need?

Another image manipulation program that will let you change projections is Iris. It's available for free at
http://astrosurf.com/buil/us/iris/iris.htm

The somewhat cryptic documentation for its Map commands is at
http://www.astrosurf.org/buil/us/iris/iris20.htm

You can tell it to input a simple cylincrical map and project it onto a sphere. Then you can reproject it to a simple cylindrical map while specifying a different north pole. It'll be a bit of work since you'll have to do it several times from different viewpoints and then merge the results into a single map.

[edit]
Iris is only available in binary format for Windows
[/edit]

Yet another map manipulation package is MMPS.

It's available for free at http://www.users.globalnet.co.uk/~arcus/mmps/mmps.html
You'd essentially have to do the same manipulations as with Iris.

[edit]
MMPS is available only as souce code in tgz format.
[/edit]

Buggs,

probably what I proposed above is not what he wants, although it looks cute There is an icy belt around the equator of the new earth ...


If he really just wants to rotate the earth's axis (without any further distortion), one needs to invoke projection software, like I was using frequently. You have to start from the given cylindrical projection to reproject it into a spherical view. Thereafter you redo a cylindrical projection from that wrto another axis.

But since he uses Windows I cannot help more explicitly. My software (MMPS, see Selden's post above) needs Linux or CYGWIN on Windows. From Selden comments I vaguely remember a similar projection program for Windows.

Bye Fridger

Oh well, Ill try to get used to those programs you suggested Selden, thanks.

I was just thinking on this. Perhaps it would be far easier to convert TO a cylindrical from another projection (which exist aplenty). I will look into this a bit tonight.