Make continent-scale heightmap based on existing coastline

[Amy Worrall]

I'm trying to make a realistic height map based on a fantasy sketch map. I know the shape of the coastline, the size, and details at the level of "there are mountains here" and "there are plains here". I know the locations of some rivers, and some other features, but there's plenty of scope to add additional stuff.

What software can I use that can:

1. Work at that scale (I need a map of size about 1500x1500 miles)
2. Let me start with my known coastline
3. Will help me build mountains in the places I want them, etc, adding realistic erosion.

I don't need 3D rendering. (Well, I want to do some, but I'm happy to do that in a different program if necessary -- I definitely want access to the 2D height map either way!)

[Turambar]

I'm trying to make a realistic height map based on a fantasy sketch map. I know the shape of the coastline, the size, and details at the level of "there are mountains here" and "there are plains here". I know the locations of some rivers, and some other features, but there's plenty of scope to add additional stuff.

What software can I use that can:

1. Work at that scale (I need a map of size about 1500x1500 miles)
2. Let me start with my known coastline
3. Will help me build mountains in the places I want them, etc, adding realistic erosion.

I don't need 3D rendering. (Well, I want to do some, but I'm happy to do that in a different program if necessary -- I definitely want access to the 2D height map either way!)

My recommendation would be either Wilbur or Gaea. There are some tutorials on here for both programs.

[Amy Worrall]

My recommendation would be either Wilbur or Gaea. There are some tutorials on here for both programs.

Can Gaea cope with that sort of scale? From my searches, I thought it couldn't without having to tile things. Any experience of using Gaea with very large maps?

[Turambar]

Can Gaea cope with that sort of scale? From my searches, I thought it couldn't without having to tile things. Any experience of using Gaea with very large maps?

You certainly can, it just takes some adjustments. But Gaea can really do any scale from up close rocks to planetary heightmaps. However, for mapmaking purposes, I have found Wilbur is still much quicker for world scale maps. I often use a combination of the two.

[Amy Worrall]

For Wilbur, do you know what a plausible maximum size in pixels is? It crashes if I try to do 1.5 million pixels across -- I know I don't necessarily need 1m scale for the high level map, but the more detailed I can make it the better. Also, how do I tell Wilbur how many metres each pixel represents? I assume that is necessary knowledge for e.g. erosion algorithms to work?

I'm trying to decide whether to just bite the bullet and accept I'll be working on smaller sections at once and compositing in Photoshop, or whether I can get a tool that'll let me work on the whole thing all together.

[Redrobes]

How I do it:
https://www.cartographersguild.com/s...ad.php?t=33666

[waldronate]

I agree with Turambar's recommendations. I will also suggest that the better the quality of the input, the better than quality of the results because most software can elaborate small details better than it can generate big-picture stuff. Also, expect that the results of most sims are unlikely to be "realistic", but are definitely likely to be "plausible" (that is, features will likely be self-consistent, but may bear only a passing resemblance to real-world places because sims tend to use too many of one kind of feature and too few of another).

https://www.cartographersguild.com/s...ad.php?t=30645 is a similar question from ten years ago and I expect that the state of the art has no doubt advanced well beyond what was discussed there.

Some examples of what one particular elderly piece of software (Wilbur) can do with sufficient fiddling around can be found by searching for "johnsondale" here at the guild. https://www.cartographersguild.com/a...chmentid=43440 is the original CSU Johnsondale map result for reference. Another example can be found at https://www.cartographersguild.com/s...ad.php?t=28052 with the high-resolution result at http://fracterra.com/wilburiax.jpg if you want to skip past the thread.

Another common solution is to use collaging (stitching together real-world heightmap pieces). You can do this manually common image editing tools by slicing up existing DEMs and rotating/stitching them together (https://www.cartographersguild.com/s...ad.php?t=51301 has a discussion of this technique), but there are undoubtedly many software packages these days that can do a semi-automated result. About 20 years ago, Howard Zhou showed a result that used flow analysis and automated collaging to match the flow constraints, but I never saw a commercial result from it ( https://www.howardzzh.com/research/terrain/ is his project page ). It's been a while since I've looked too much at these kinds of techniques and it always required way too much talent and technique for my tastes.

As what you want broadly comes under the heading of image synthesis and/or style transfer, I would expect that many of the "AI" image synthesis tools can get you started. This is especially true if the backing model will take an input image and let you say things like "convert this sketch of a map into a heightmap and replace the brown areas with plains, light blue areas with rivers, dark blue areas with ocean, yellow areas with hills, and gray areas with high mountains." Or something like that. I'm not what the kids are calling a "prompt engineer" (similar to a "sanitation engineer", I suppose) these days.