this post was submitted on 22 Feb 2025
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I have a clear globe that i would like to project to a flat map. Any common projection should work, since computer programs exist for converting map projections. Where should i start?

A couple of details: First, my "globe" is an empty plastic Christmas tree ornament, so it can be hung from a string at one end but it doesn't have a stand like a normal globe does.

Second, this is a worldbuilding thing. My globe does not represent any real planet or similar body, which is why i need to make a new map from the globe instead of finding an existing one.

EDIT: To be clear, i know about projections already. I'm not worried about picking a projection. What i'm asking about is the process is for taking a physical globe and projecting that globe's surface onto a flat rectangle. I don't know how to turn an imaginary cylinder or cone sitting on my globe into a tangible physical or digital map. I don't have the means to cut up and unfold my globe until it's flat. What is the actual process for making a map from a globe, for any projection? I know this isn't how maps are traditionally made, but surely there must be a good way to do this.

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[–] Successful_Try543@feddit.org 2 points 1 hour ago

The process of actually projecting the contours on the globe onto a flat (cylindrical) map is by either putting a strong light source inside the globe and place the paper cylinder around it. This projects the contours onto the cylinder. The contours then need to be traced onto the cylinder using a pen. The other option, e.g. if the globe isn't translucent, is to paint a longitude/latitude grid onto it and start with an empty map with the same grid. Then, for every trapezoid on the globe, its content needs to be transferred to a rectangle on the map.

[–] StellarExtract@lemm.ee 4 points 6 hours ago* (last edited 6 hours ago)

I'm not a cartographer, but the way I'd tackle this is to drill a small hole in the globe and spray paint in through it, so that the inner surface is opaque white. Then I would put together a cheap turntable-style 3D scanner using an off-the-shelf camera (there are open source designs available for this that you can buy as a kit or print using a 3D printer, then assemble following step-by-step instructions). Then, after scanning the globe and obtaining a textured 3D model of it, it should be relatively easy to convert the globe's texture from a spherical shape to a standard map projection using software. I don't know what software that would be offhand, but I'm sure it exists.

[–] potentiallynotfelix@lemmy.fish 3 points 7 hours ago (1 children)

Objectively, the Gott, Goldberg, and Vanderbel projection method distorts the least.

[–] Balthazar@lemmy.world 3 points 7 hours ago (1 children)

For some definition of "least".

[–] potentiallynotfelix@lemmy.fish 4 points 5 hours ago (1 children)

Using their own scoring system for distortion, a globe would be a 0, a Mercator projection would be 8.296, Winkel Tripel is a 4.563, and their projection would be a 0.881.

[–] Onomatopoeia@lemmy.cafe 2 points 2 hours ago

Well, gee, thanks for the rabbit hole!

[–] Zotora@programming.dev 6 points 9 hours ago* (last edited 9 hours ago) (2 children)

Any projection is a compromise. You conserve some properties at the cost of others.

You could always start with a mercator projection. They are easy enough to make (think cylinder wrapped tightly around the 'equator' of your globe.

Or you could go with a conic projection (think cone sitting on a gloabe like a hat) which are also simple to make. Lambert conformal conics are common in aeronautical charts.

Both of these projections are used in different maps in the real world for navigation.

Edit: Go for a browse; there are plenty of different flavors https://en.m.wikipedia.org/wiki/List_of_map_projections If your using software, then you can kinda do whatever you want without worrying about how hard or easy it is to make. 😄

[–] SubArcticTundra@lemmy.ml 4 points 5 hours ago (1 children)
[–] Zotora@programming.dev 1 points 3 hours ago* (last edited 2 hours ago)

Not quite what i meant haha: A conic projection uses a 3D cone laid over the top of a 3D globe and then the cone is spread out on a flat surface, rather then the map itself being a cone as you have done above.

The videos below might help illustrate what i mean.

Some relevent Videos:

[–] TropicalDingdong@lemmy.world 2 points 9 hours ago (1 children)

Mercator always a.crowd favorite.

[–] disguy_ovahea@lemmy.world 1 points 9 hours ago (2 children)

The AuthaGraph is considered the most accurate flat map from a globe.

http://www.authagraph.com/top/?lang=en

[–] SubArcticTundra@lemmy.ml 2 points 5 hours ago (1 children)

I guess you want a projection that distorts your oceans whilst keeping your land masses as proportional as possible, right?

[–] disguy_ovahea@lemmy.world 2 points 5 hours ago

Very good point. It would depend entirely on the locations of the land masses on OP’s globe.

[–] sxan@midwest.social 1 points 8 hours ago

Better than Butterfly? Better than Dymaxion??