Reply With QuoteDoes Google Earth do that kind of stuff?
building a 3d world globe
I found these instruction on internet about which projections are needed to build a 3d earth globe:
"Create a series of 12 Transverse Mercator projections that are 32 degrees in longitude and 91 degrees in latitude to form a "flower petal" projection for making globes. If the northern hemisphere is being created, the latitude range is -1 to +90. If the southern hemisphere is being created, the latitude range is -90 to 1. The petals are formed by changing the center longitude and map rotation in steps of 30 degrees for each Transverse Mercator projection. Each section is put into the mosaic. The final center of the projection is a Lambert Azimuthal Equal-area centered on the pole and covers from -90 to -75 or 75 to 90 degrees latitude and 360 degrees in longitude. This is the last cube that is placed in the mosaic"
But I can't find suitable (free) programs to obtain needed projections!
Any help?
I need a Java or Windows program which any raster image input and produces raster output.
Last edited by jumpjack; 02-05-2009 at 08:47 AM.
Does Google Earth do that kind of stuff?
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Nope google earth doesn't do anything like that.
Your easiest choice is to use a flattened dodecahedron (20-sided die) map, sort of like the maps traveller used, and then glue the sides together appropriately.
Either that, or just paint your map on a spherical object to begin with.
it just SHOWS a globe, I need to PRINT it to BUILD it.Originally Posted by Steel General
no, I want to print one of these:
http://astrogeology.usgs.gov/Gallery/MapsAndGlobes/
But I want to be able to choose MY map and MY size.
it just SHOWS a globe, I need to PRINT it to BUILD it.
Sorry I misread what you wanted to do
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You can do a globe with many different kinds of projections. The idea is to get small enough pieces to cover the globe without too much distortion when you paste them down. For example, sinusoidal gores (optionally with azimuthal equidistant endcaps) work well.
I have used Fractal Terrains ( http://www.profantasy.com/products/ft.asp and Wilbur ( http://www.ridgenet.net/~jslayton/software.html ) to generate images for such projects in the past, but there are more modern programs out there such as G.Projector ( http://www.giss.nasa.gov/tools/gprojector/ ) or FlexProjector ( http://www.flexprojector.com/ ) that might be better suited for the task. G.Projector wants input in the equirectagular projection but that's doable (I have successfully used my elderly ReprojectImage program at http://www.ridgenet.net/~jslayton/ReprojectImage.zip for this task). I haven't done much more than just barely play with FlexProjector so I can't say how useful it would be in this context.
There were a few discussions here about making globes here a while back ( http://www.cartographersguild.com/showthread.php?t=2109 is one) so there is probably additional information drifting around.
Attached is an example of the old Forgotten Realms Interactive Atlas map reworked for cutout and paste to a globe. It was reprojected from its original Equirectangular projection to the one shown in one step in Fractal Terrains.
I also responded in this thread:
http://www.cartographersguild.com/showthread.php?t=4216
Not sure if they are for the same thing or not. If OK, I would like to merge the threads.
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I played a bit with it, but I can't figure out how to produce a Lambert Azimutal Equal Area projection centered on north pole, can you please help?
Thanks, I searched the forum a bit, but didn't find that thread.There were a few discussions here about making globes here a while back ( http://www.cartographersguild.com/showthread.php?t=2109 is one) so there is probably additional information drifting around.
@Roba:
yes, it's the same subject, I posted in different forums because I didn't know which one was the more suitable (i.e. which section usually is read by users knowing solution to my problem)
ReprojectImage takes an image in some projection other than Equirectangular and produces an image in the Equirectangular projection. This step is usually the hard one. You would then take that image and run it through a piece of software such as Wilbur or Fractal Terrains (I'm most familiar with those two as I wrote them).
In Wilbur you would reproject the Equirectangular image as follows:
1. Load the image using File>>Open with the Type set to Color Image Texture.
2. Set the map boundaries using Surface>>Map Info (Top=90, Left=-180, Right=180 and bottom=-90 for a whole-world image).
3. Reproject the map using Window>>Map Projection. Pick the desired projection (Lambert Azimuthal Equal-area in this case) from the drop list and drag the image in the window around to get the desired result. For world endcaps you will want a Center of Projection with Latitude=90 for the north pole and Latitude=-90 for the south pole.
4. Click Export BMP on the Map Projection window to save a bitmap of the desired resolution.
Below are examples of this process on a basic Earth map to get polar caps.
Last edited by waldronate; 02-06-2009 at 04:42 AM.
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