Well its just that most terrain based apps work off of a height map which is just a greyscale bitmap. So you can use the lighten and darken in any paint package to modify it. Then you only need a small app to show the height map in 3D. I used to give one away but right now I haven't got one to hand. But you can easily do it in any number of apps. Blender does it great but there is a bit of a learning curve to get that sorted and I know I have seen a few people post on here about how to do that. Also, I know a very quick and dirty way to get a 3D view of a lower res terrrain is to use OpenSCAD. The bonus being once you have that correct you can export it for a 3D printer and handle it. There are numerous but to my knowledge I think Celestia does it well and I think Wilbur will and that has the bonus of being able to apply lots of processing to it like erosion and other natural effects. Obviously some of the big gun terrain apps will do it too for a cost like World Machine and Terragen etc. But since I use my own stuff I don't have a lot of experience with other apps.
I am not into Macs so not sure whats available for an iPad. Can you use Windows or Linux based stuff ?
Edit: For info, in OpenSCAD I got a nice 3D image with code in one line like this:
Code:
scale([1, 1, 0.5]) surface(file = "Terrain.png", center = true);
Where I had a small 256x256 sized Terrain.png as a full RGB file with only greyscale image on it where white is high and black low.
Also:
https://www.cartographersguild.com/s...ad.php?t=22236
https://www.cartographersguild.com/s...ad.php?t=35516