Hello! I'm messing around with large heightmaps that have tall and sharp mountains - specifically the USA heightmap available on BaNaNaS. I've cut it in half (I only want the west half), and blown it up with an image editor to 4096x4096.
Unfortunately, OpenTTD seems to really struggle with the mountains. With default settings, the Sierra Nevada is cut off and flat on top - the game does not render anything higher than a certain point. Unintuitively, though, this isn't simply a max height issue, as I can set the max map height to 255 and still get cutoffs in places (many of which apparently aren't even at the max height), and that still causes a lot of the rest of the map to be rescaled upwards and more bumpy than I'd like (eg causing San Francisco to be just a straight peak, and thus annoying to found a city at; or having mountains with bases seemingly too wide).
At the moment, my solution is to rescale the heightmap colour gradient in the GIMP, but this is rather unsatisfactory, as I can't seem to preserve both tall mountains and shortish hills, and getting a reasonable result requires some very good precision defining the rescaling curve (or else I get odd things like foothills starting suddenly, then flattening out, then rising sharply again).
Does anyone have suggestions for ways to cope with this? My goals are:
- No cutoffs (or tiny cutoffs at the highest points)
- Reasonable foothill behaviour
- Not obliterating lower features (I'm happy with a bit of unrealistic scaling where this is concerned)
- Not having lower features problematically sharp thanks to having everything scale up to a huge max height
It may simply be that I need a better rescaling curve in the GIMP, but I'd like to hear if there's an easier solution. It would be nice if I could somehow set the worldgen to not -necessarily- go to the max height, and only go as high as it really needs to. I suspect, though, that I might just have to use a larger map in order to really get what I'd like; but so far, it seems that increasing the map size causes the cutting off to get -worse-.