Software that meets specific technical needs in manipuation of projection and display

[Snargash Moonclaw]

I need to be able to take a pair of (north and south) polar projections and manipulate the display of that data to show an accurate flat map display of the equatorial region which is cut in half by the polar projections. The following hand drawn maps should make the actual need and requirements pretty obvious.

The two flat maps are an the equator progressing eastward within the first 1/8th sections of the polar grids- I need to be able to take the polar projections and zoom in on any part of this and the next 1/8th segments moving eastward around the circumference of those grids so that they are joined together in that same fashion, if need be modify/clean up the flat map and have the changes likewise carry over into the polar displays. In short, have a single set of visual mapping data which can be presented both in polar and Cartesian projections. I think CC3 may be able to do this, but I'm not sure. If more than one program is capable of this then the next criteria tend to be finances followed by ease of use although small increase in the first may be worth substantial increase in the latter.

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[waldronate]

http://www.jhendor.de/tutorials/cc2-ft.pdf shows how Ralf over at ProFantasy did something similar years ago. Steps 1 through 4 should be applicable.

There are better bits of software out these days that some of the folks hereabouts prefer such as G.Projector or Flex-projector.

[Snargash Moonclaw]

http://www.jhendor.de/tutorials/cc2-ft.pdf shows how Ralf over at ProFantasy did something similar years ago. Steps 1 through 4 should be applicable.

There are better bits of software out these days that some of the folks hereabouts prefer such as G.Projector or Flex-projector.

Thanks for the input. Unfortunately the tutorial doesn't really offer any info on converting projections - while he started with a polar projection in CC2 and ended with the type that I would like (to go back and forth between) that seems to be more of a side effect of whatever he was seeking to accomplish in converting the data format from CC2's to FT. I didn't really comprehend most of it as I have never used either program nor any of the other utilities he utilized during the intermediate stages.

I am hoping to locate a single program that will simply handle both types of projections from a single initial map. (Which is why I'm wondering if CC2 or 3 would do that - if the change in projection had been all that he was seeking did he even need any second program?) Because of the unusual way the two continents are situated over and surrounding the two poles I have to start with the polar projections when mapping the entire globe. I simply can't perceive the coastlines and other features clearly and properly in my head in another type of projection to draw them broken apart in pieces or spread out linearly. Even having the initial polar projections I still find it extremely difficult to attempt to map the more extreme parallels by hand in any sort of rectangular presentation.

The two programs you mentioned looked promising, but after downloading and running both I found that neither will deal with polar projections in any fashion (starting or ending) - they work solely with rectangular representations of an entire globe centered on the equator which adjust for the distortion that flat Cartesian mapping produces as you approach the poles. I may have use for them later, but sadly they don't do what I'm needing here since they start and end with variations on the sort of projections I'm unable to produce.

HF, PW,
AOK
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[waldronate]

Using ReprojectImage I got the first two images shown below and assembled them in Photoshop to get the third image (approximately the equirectangular projection needed for the other reprojection programs). Putting that image into FT I got the last image, which shows that world on a globe.

Note that this was a quick operation and I didn't fiddle with the parameters to reprojectimage to get a perfect layout. Some things don't perfectly line up along the equator and the lines aren't perfectly straight. The curved lines are caused by not getting the reprojectimage parameters correct. Things not lining up correctly may be partly due to that problem but may also be partly due to source material.

I tried to get the other images to line up but I couldn't find a good location to do that.

[Snargash Moonclaw]

That globe totally rocks! It also tells me that I need to make some changes to my coastlines to get what I want in this perspective (the projection is very informative) - bring them a little further down from the poles and carry the southern continent's equitorial coastline eastward more before turning it south as the concept for the equatorial (The Suntrack) Sea is a longer band of water between the two continents. I would love a program that would create this projection from the two polar ones and allow me to make the changes I mentioned directly on the global projection then convert the modified file again back to polar or some other projection. I get the feeling that CC3 is the only likely candidate in that regard but I don't know if that can even do it.

As far as my attempting to repeat the process you used, what is ReprojectImage, where is it available and is it free/share/or market ware ? Will GIMP do the photoshopped step? While I'd have to purchase FT, even being able to create an acurate equirectilinear projection would be very useful and the two projector progams you mentioned earlier can take care of a lot of the distortion. I knew I'd have mapping problems when I first envisioned the planet but its unusual geography creates some desirable effects upon the game setting.

[waldronate]

ReprojectImage is a program I wrote long ago to get general map projections into the equirectangular/Plate Caree projection. It's the tool that Ralf used in his tutorial to reproject his image to get it into FT and can be found at http://www.ridgenet.net/~jslayton/ReprojectImage.zip if you'd like to fiddle with it. It's free to use.

GIMP or any other image manipulation tool will work well for manipulating the images. All I did in Photoshop was up the contrast of the base images and stitch together the two half images.

FT isn't a required part of the activity, it was just convenient way to do the globe projection. There are many other ways to do that part, including Wilbur (http://www.ridgenet.net/~jslayton/software.html). Please note that I am in no way attempting to discourage you from buying a copy of FT.

CC3 doesn't do projections.

I would recommend working on the equirectangular projection if you can because going back and forth between projections causes some pretty significant distortions of the image near the pole.

[RobA]

Here is the exact same thing done completely in gimp...using the polar/rectangular filter on each hemisphere.

I was hasty in selecting the initial squares (or the source is off as waldonrate states).

And I'll throw in the sphere, too, also vanilla gimp.

-Rob A>

[Snargash Moonclaw]

Hmm. Will anything permit me to work on this in the way I was describing? I don't really know what the different programs will do. I have GIMP but really don't know how to use it - basically I've just resized pictures with it - I know nothing at all about graphic software. I'm simply trying to find something which will let me perceive the mapping data (image) in different ways and edit it in them. i.e. - both globes (the one RobA did in GIMP and yours) only show a portion - what would let me move the globe around (as if I were in Worldwind or GoogleEarth)? I don't understand your last recommendation - the equirectangular projections are extremely distorted around the edges - I don't see how I could work in them if I were doing anything to the coastlines beyond about the 45th parallels. After doing some referencing those coastlines may not be as bad as I first thought seeing the globe (but I need to see them completely in that form) - the planet's axial tilt is less than Earth creating ant/arctic circles at about 73.5 degrees and tropics at about 16.5 rather than 66.6 and 23.4 - those are the red lines - not specifically calculated - placed on the polar projections as eyeball approximates of where I want them.

HF, PW,
AOK

CC3 doesn't do projections.

I would recommend working on the equirectangular projection if you can because going back and forth between projections causes some pretty significant distortions of the image near the pole.

[Snargash Moonclaw]

How did you do this? I'll be checking into the tutorial - but as I said above, I don't really even know the basics of the GIMP and what it can do. I'm currently struggling just to cut the two polar projections out into separate circular image files which I can blow up to fit a standard page and print.

Here is the exact same thing done completely in gimp...using the polar/rectangular filter on each hemisphere.

I was hasty in selecting the initial squares (or the source is off as waldonrate states).

And I'll throw in the sphere, too, also vanilla gimp.

-Rob A>

[waldronate]

Any flat representation of a sphere will have distortions when you put it on paper; that's the nature of map projections. I do not know a good drawing tool that works on spheres directly. A 3D modelling tool would likely have this capability but I'm not much up on modern 3D tools.

The image overlay painting tools in FT are laughably primitive and prone to brush shape distortion but they do let you paint on projections other than equirectangular, including orthographic (the sphere one).