How to implement large world map like in grand strategy games

I would like to create a grand strategy game.

I really like how the totalwar series or paradox creates a good looking world map.
I wonder how to do the same.

So far i used terrains and calculated the textures and heightmap of the world from images.
So far so good the real problem comes when i want to place trees and objects. Beside performance they dont really look good from high above.

Surprisingly there are also no assets on the store to create good looking worldmaps that have trees/rivers and towns.

Any ideas/guides how to implement that?

 

ok. I am your person. I know everything there is to know about how Paradox makes their Grand Strategy maps.

here's a link to a Ck2 mod with a map based on Antartica... I've modded most of Paradox's games
https://www.dropbox.com/sh/qn4m11aqhif69xb/AAAhqP29YXdDtlakga8pj8hoa?dl=0

so, for starters, you want a World Map? I can make you a nice one, only I'm a little crazy... and I got weird ideas about maps, like I would enjoy a map, say , based on the Polar projection, then maybe flattens out when the camera zooms in... or actually better, you want a Sphere maybe instead of a "flat map"?

So, a good looking Worldmap that has trees and rivers... and a normal map, and a "texture atlas" like Paradox uses, and they have a "colourmap" and some other stuff to add detail...

That's not a bad project, and I'm just learning Unity (my 11 year old son and I did the Basic Tutorials today in under an hour... ) and I could use an Earth for the project that I want to make anyway. Maybe you give me a hand, and I can give you a hand..

Ok, first question, Pixel resolution... the Big paradox maps I've looked at for HOI are 16K resolution, if I recall, and it came down to about 12 or so real world miles to the pixel on the big colourmaps. Then detail from the "Terrain" map is added from image and normal dats in the "texture atlas", the trees have their own file... but they do it Stupid.. in Unity, you could have the forests done as a "partical effect" just one that doesn't move, but could change over time, and the colors could also change to reflect seasons... yeah a lot of good ways to make a worldmap... though I'm partial to a sphere.. from what I've seen so far the whole thing could be done in 8-9 image files and some simple primitives within Unity.

I should mention that I'm totally on "Art-side" and am not a coder. I'm a script-kiddy at best

 

I "borrowed" the images from crusader kings. I was able to build the terrain from the heightmap and had to manually smooth the edges. I also painted the terrain already based on the color texture map

The idea with the particel effect is interesting but how to do you control where you show the trees.
Do you have an example where you did it?

 

that looks nice, a little lighting and detail and it would be perfect

, here is my personal favorite of the Earth heightmaps, and I'm pretty sure HOI4 is based off of this one

https://1drv.ms/i/s!AitC9GDM_LELhTbidssGV0YMMc4Y

how to control where to show the trees.. Paradox uses an imagefile, called trees.bmp.. and it's just got some shades of green... lighter green to represent sparse tree placement and darker green to create dense trees...

I did some experiments in CK2 and this was the densest jungle that I could create with their engine
https://www.dropbox.com/s/10cpfmk3vff4u9l/01jungle.jpg?dl=0

not bad really...

but, that's not how I would make trees for a grand strategy map.. mainly because the scale always bothered me... those trees on any paradox map are like 12-20 miles across... so..if I were to design my own map, Id make the forests just a thin layer over some soil covering bedrock.. as seen from space, on a globe.

ok, how I would make your image tree placement file is this... I would take the whole Earth image, the color one, and select all the green.. this would give me a pretty good start base and I'd call it Earthgreen.dds or someth8ing. (if I'm going to make a rivers.bmp like Paradox does in Ck2, then I'd just take that rivers image and use it as a "selection map" in the trees image to select and delete any trees that are in the same place as the rivers... the hard part of Rivers is making them flow downhill only)...

 

Hey, would you please post the Earth heightmap again? The link is broken.

Thanks!