Wilbur and Krita - what shade of black do I need as the lowest land in my height map?

[Mouse]

Hi Everyone... well, chiefly Waldronate, perhaps?

I've been doing some work in the background, messing around with the idea of shaded mountains - mountains that shade themselves when plonked down in a CC3 map, and I've got a bit side tracked by a request for a world map. (Odd, I know, since I'm not particularly known for my world maps, but this is a personal friend and I'm really just pottering around at the moment while I'm still not feeling very well, so I thought I'd have a go at it. I mean, just how difficult is this world map thing anyway Yeah - I KNOW about it now! LOL!)

Ok, so I've figured out that even though I have a really nice coastline shape from Fractal Terrains the mountains aren't necessarily in the right place, so I decided to use the coastline and draw the height map in Krita, so that I could then erode it nicely in Wilbur. Krita, because unlike GIMP it can work in and produce pngs that are 16 bit greyscale, and not just 8 bit like GIMP. (Working in GIMP leaves you with a few nasty terrace problems to try and resolve before you even think about erosion and stuff in Wilbur, which uses 16 bit greyscale height maps)

So I painted my land shapes not quite black in Krita, and painted my mountains in, using a sheet of fractal noise that I'd previously crafted in Wilbur, and almost immediately hit a problem.

The mountains are working out fine, as you can see below, but I can't work out exactly what shade of not quite black to paint my land shapes so that they are seen by Wilbur as being land, rather than sea. In the 16 bit greyscale there are 65535 different shades of grey between black and white, but which one of them should I be using to avoid the land itself looking like its way higher than the ocean (note the small cliff around the coast)

At the moment I have it shaded at grey 2570 on that scale, but I think it may be a bit high. What I'd like to know is - what is the right shade of grey to use for my land base in my height map?

[waldronate]

Wilbur interprets value 0 (the blackest black available on your 16-bit grayscale range) as sea level. The first grayscale value (1) above that will show as land. If you're getting cliffs around the sea, then you're not painting the first grayscale value as your first non-sea value.

I wouldn't worry too much about the absolute numbers in the import because you probably ought to be scaling the input to get your desired values. If you're going to go with the idea of grayscale values having some real-world value (e.g. 1 gray shade difference means one meter altitude difference), then sea level would be at 0 and you can't have any subsea topography and you will have 1-meter steps in your landscape. If you go with the notion that the grayscale values are just a convenient way to show differences, then you can pick an arbitrary grayscale value to be sea level, define white as some maximum altitude, and then offset your import by -grayscaleSeaValue and scale by desiredMaxAltitude*grayscaleMaxValue/(65535-grayscaleSeaValue). Or use Mathematical>>Span to go from your minimum altitude to maximum altitude. For example, if you define grayscale value 0 (black) as -20000 meters and grayscale value 65535 as +20000 meters, then grayscale value 32767 will be sea level. After importing into Wilbur use Filter>>Mathematical>>Span with values of -20000 for low and +20000 for high to get your final altitudes. You should make sure that your import map has at least one pixel of the minimum intended grayscale value (0) and one of the maximum grayscale value (65535) if you're using span to ensure that things don't have and undesired offsets or scales.

In Wilbur, you can figure out how high that cliff is by moving your cursor from the sea area (which should be reading as 0) and just move it one pixel onto land. You can use Filter>>Mathematical>>Offset with the negative of that cliff value to push the terrain down to sea level and then use Filter>>Height Clip with a low value of -0.01 and a high value of 100000000 to get rid of things below sea level.

[Mouse]

Thank you very much! Such a rapid response

I see I've been going about it all wrong (as per usual for me).

Thanks again. I can sort it all out a lot better now

[Mouse]

Well as you can see I've managed to solve the problem using the Mathematics>>Scale option, and setting the scale to max 39321, min -26214, and painting the land 26214+100. The added 100 seems to make it work better, even though its 100 shades above sea level

Now the only cliffs I have are those where I've accidentally painted the mountain texture sheet too close to the coast and consequently made it a bit too pale.

(This is only a draft example with a couple of experimental layers added in Krita btw)



EDIT: I can see from a comparison of the two images that I might have lost something in the interpretation of the mountain texture, but I'll work on that