Hi-Res topographic maps, equal area projections

[Siegfriedfr]

FAQ

What is the goal of this thread?
Learning to get hi-res topographic maps with a flat earth-curve projection of any part of the world quick and easy.

What's new here?
I've looked in the numerous mapping tutorials on twcenter but couldnt find one which would point me to hi-res maps of the world and how to "curve" them to get equal-areas projections.

What is an "equal-area" projection?

Instead of having a flat rectangular map, you can bend and curve it to mimic closely the curving of earth on a flat surface.
Practically this allows 2 things for total war modding:
- remove alot of steppe/desert area in excess
- properly depict the size of each area

Examples:
Classical "Robinson" projection:


Alberts Equal Area Projection:


PRACTICAL EXAMPLE!

Robinson projection:


Albers Equal Areas projection:

Step 1 : Where can i get hi-res maps of the world for free ?

When creating a R/M2 TW map, you need the following ressources:
- a topographic map for heights; [most important and the base for all your work]
- a watercover map for inland waterbodies;
- a landcover map which is not necessary to create a mod but helps immensely when drawing rivers and outlining deserts/grass area;

The NASA provided the web with the bluemarble project which is a collection of satellite images of Earth.

[For our purpose and if you are a beginner, you only need 5400x sized maps - it's however entirely possible to use the 21600x maps as a base before downscaling if you have the hardware and knowledge of mapping]

The map download center can be found here

Easy links:
Topographic map
File :srtm_ramp2.world.5400x2700.jpg
Ocean's Cover
File :world.oceanmask.5400x2700.png
Landcover map
File :world.200407.3x5400x2700.jpg

Step 2: How to get "equal areas" map projections ?

The NASA also provides a very nice tool : the G projector: Global Map Projector, allowing you to modify the "projection" of a map
The best one is arguably the "Albers Equal Area Conic", which bends the map and respects landmass' size.

[This software only loads images 5900x or smaller]

Once you "projected" your flat map, you can zoom in or out, remove the grid, determine the "center" of your map etc...and eventually save your work as a jpeg file.
[Max resolution supported when saving seem to be 2500x]
[You should save in the jpeg format and then transform to TGA format with gimp]

Step 3 : How do i modify TW map files ?

Gimp, a free and powerful image editor almost equal to photoshop, at least for TW map-modding:

Gimp - GNU Image Manipulation Program



What you NEED to master in gimp in order to succeed in mapping:
- extensive use of layers
- color selection

It takes alot of trial and error, trying and failing before understanding how to use gimp efficiently and create a proper map.
Patience is key!

For the next steps in mapping, i leave you browsing the numerous quality mapping tutorials on totalwarcenter!