From paint to photoshop - collaborative worldbuilding - advice needed

[Lawrencelot]

Hello all. This is my first post here so sorry if I do something wrong. On another forum we started a collaborative world-building game, where players add one country at a time, in paint. This has resulted in the following map at the moment:
colabwb10.png
All the countries have a name and backstory, and the white area is not yet claimed/explored. Now, for aesthetic purposes and also to be able to play a game (atwar) on the map, we were thinking of making a geographical map for this world. I tried some photoshopping techniques I knew together with the atlas tutorial to make this:
cwb_geo_labelled2000.png
Note: the labels are copied from something else, they are not done yet.
I was hoping I could get some advice on the following:
-How can I make the pixelated areas smoother?
-How should I tackle the rivers?
-I want to include land borders as well, but I'm not sure how to do this, as the edge function in photoshop gives all the mountains as well.
-I did not follow the atlas method for the mountains, but just used a standard photoshop texture, is this fine? I used the same texture for underwater mountains as for normal mountains but there might be another option.
-The lines in the south are supposed to be huge waterfalls. Any idea how I can change the paint version to a realistic version?
-The North Ring is supposed to be a mountain range of immense height, separating two worlds. Does this come across? Also, the ice world north of this range is supposed to be some kilometers higher than the main world, any ideas to get an effect for this? And can you see it's ice? Because right now it looks more like sky to me.
-The world is supposed to be doughnut-shaped, not spherical. Are the grid lines correct for this?

Hope you can all give me some feedback and help me out. Thanks for your time!

[johnvanvliet]

-How can I make the pixelated areas smoother?

define that
i have zero idea about what you are referring to

if you are seeing single pixels then enlarge the image

[Lawrencelot]

define that
i have zero idea about what you are referring to

if you are seeing single pixels then enlarge the image

These are some areas that don't look natural to me, in the sense that you can clearly see that it came from an originally smaller image:
cwb_geo_labelled_pixelatedareas.png
(click the image in the first post to zoom in on the areas)

[Lawrencelot]

I've tackled the pixel problem more or less doing something like this:

-make a selection of the coastline: 2 pixels inland and 2 pixels into the sea.
-make a new label
-generate Gaussian noise in the selected area.
-fill original land with black, original sea with white
-use magic wand to select the new land. Same with sea. Adapt land and sea

For the rivers, I have just used a pencil of 1 pixel in size. There are some artifacts but they don't bother me too much now.

Any advice on the other points? Especially the waterfall looks like a real challenge, I wonder what a massive waterfall would look like from such a distance

[Azélor]

-I want to include land borders as well, but I'm not sure how to do this, as the edge function in photoshop gives all the mountains as well.

I usually just draw them with the pencil tool or the paintbrush if you want something smoother. r if every country have a shape, add another border around them, on another layer from the mountains.

-The lines in the south are supposed to be huge waterfalls. Any idea how I can change the paint version to a realistic version?

At this scale, each pixel represent several square kilometres. The highest waterfall might spread to 2 pixels if it was about the size of Mt Everest which would be very unlikely using normal physics.
Also, having so many waterfalls there is unlikely to happen without a serious magical help.

So it depends if you what the scale of the waterfalls to be consistent with the rest of the world or not.
If it's larger than it really is then it l would put white vertical and irregular stream of water with some mist around it especially near the bottom.