Putting Gores to bed.

[Redrobes]

Every few weeks we have a question on how to make a map with Gores projections. Why use Gores ? Well its usually done so that you print out the result and then cut out the shape and glue it to a sphere to make a globe.

There are other solutions but I thought I would make a windows and linux app for everyone. You can copy this and give it away (freeware) but its not open source. If you find bugs then let me know.

I have a windows ZIP file containing a 32 bit and a 64 bit version. As usual its a simple command line app.

In linux there is only one 64 bit app (and I hope it works based on your version of the C standard libs). As usual you open a terminal and run it.

All versions contain the usage and help info for the args. But basically its a variant of:

Gores.exe 12 Input.JPG Output.png

To give you a 12 gore version of the input file which should be a usual type of mercator / cylindrical projection.

I have tested it on 16K x 8K images no problem and it uses bi-linear interpolation.

Feedback welcome.

[WilliamLear]

I have used the program a couple of times, it looks good.

Now I want to draw a parallel on it, it turns out like this (topview):


I am new to mapping the world and spheres, can't find a solution. Do you know how I can fix this?

[Redrobes]

I am guessing you want the app to generate the top view.

But if you are asking if the app will put a line like that on the gores reprojection from a horizontal in mercator then my app wont because as was pointed out to me, I cut corners and squsihed in the X axis only. There is supposed to be a subtle Y shift too. So if you generate the gores with my app then the parallel will bend slightly and look like a spiders web. If you use a lot of gores like 36 then the effect is minimal but if you go with 8 like your image it will be more noticeable.

There are loads and loads of posts about gores and there are many other solutions which do include the top view and the compensation of the Y axis too but most are more tricky to use. I dont think that I have time right now to adjust my program to do that compensation, or add in a top & bottom view generator to it too.

But if its allowable in your situation then draw the parallel on the mercator map and use a lot of gores - like 36 or something then it will probably be sufficient. I.e:
Gores.exe 36 Input.JPG Output.png

[WilliamLear]

The topview is only to show what I happens, don't need it in any other way.

I'm already looking into other programs (not a lot of time lately).
I liked your program because it's fast and easy to use. I thought maybe there is an easy fix that I could do to make it work.

Thanks for the reply, I will look into it