[Award Winner] Building a ridge heightmap in PS

[RobA]

That works pretty well!

I'm still playing but this is what I have managed so far...

-Rob A>

[su_liam]

Nice work RobA. I assume your using GIMP and, maybe povray?

It seems less clumpy/hummocky than my results. I presume your blurring it and then using an iteration of spread/blur/dilate. Part of the difference is that I think the dilate filter in GIMP is strictly 1 pixel at a time. If I understand Dilate properly, the single pixel dilate, or contract basically looks at a 3x3 neighborhood around each pixel and sets the pixel to the smallest value it finds(Erode or expand sets the central pixel to the highest value it finds. With a radius of 3, as I've been using, contract finds the smallest value in a 7x7 window this is naturally clumpier. I've also been using a second pass with the Spatter filter with a higher smoothing value. This can be simulated nicely in GIMP by using a pass with the Pick filter after the Spread. Hopefully, that might help, if you WANT the more hummocky look. Also, adding more fractal noise at the end with clouds makes a difference.

Actually, I've been meaning to do an experiment with a more conservative spread and blur, no intentional clumping stage, and a slower, but less clumpy radius 1(3x3) dilate. I'm hoping it would make a good approximate way to remove terracing. Better than my previous erosion idea. Still not so good if you want an exact interpolation, but hey...

I think I'll call it the Stochastic Deterrace Algorithm if it works. Heehee!

[su_liam]

Hi in the vast Himalayas, water, wind and ice have conspired to create this odd formation.

I put a High Passed differenced Cloud fractal under a blurred, noised and dilated text layer. The text is applied using Linear Light(additive) mode. In Bryce, I applied(perhaps too much of) both types of erosion.

[pyrandon]

This is amazing! Ok, you've convinced me: I need to play with these apps and your process!

[su_liam]

I'd give my left pinkie and two toes to be able to do this in 16-bit. Or better yet 32-bit float...

[Redrobes]

I'd give my left pinkie and two toes to be able to do this in 16-bit. Or better yet 32-bit float...

Heh heh - GeoTerSys is float...

Anyway, I was going to say that this looks just great - thats some nice erosion effects there.

We have found that getting from this stage to the next is where it gets hard so ill pick your brains. In a real landscape the water runs downhill and pools up. In almost all systems the app does not compensate for this which is why I was challenged to write GTS in the first place. What we have seen is that in almost all terrain you get lots of huge pools. We have a solution but I'm telling ya that GTS takes ages to run and if we could feed it nearly right terrain then it could fix it up a lot faster. Do you have any tips n tricks so that the valleys in these mountain ridges would form terrain that would not pool up water. Sorta glacial U shaped ones. I know thats a tall order but thats what I am up against - not just providing it but providing it at a rate thats not so stupendously slow that its going to take multiple years to generate.

If your more interested then post the grayscale heightmap of the Hi in the mts and ill post some more.

BTW, Can't Bryce use 16 bits formats then ?

[su_liam]

Bryce accepts 16-bit formats. Photoshop is the problem. PS7 can open 16-bit files, it just can't do much with them. Possibly, you could create an 8-bit file in 512x512 resolution(for example), and interpolate it up to a 16-bit file in, oh, 4096x4096 with GTS, perhaps?

Erosion is kind of a sore point with me right now. I just spent more than a month trying to implement linear precipiton erosion in planetgenesis, and I have nothing to show for it but a huge mass of nonfunctional kludgy code that I just don't understand anymore. Too many little hacks trying to make it work rendered it incomprehensible. I'll have to start over from scratch, but I'm not up to it at the moment. If I ever get that going, I have some thoughts about using a pit-fill algorithm to find an edge to the lake and then erode the pit down starting from the low point that stops the pit-fill. Still a little nebulous, and I haven't put much thought into it while trying to get the $%#@ precipiton to work.

I wonder if geologically very young areas more closely resemble the results of applying fractal noise. Maybe hills could be gradually built up in user defined areas with frequent erosion steps in between? Hmmm...

I've been playing around with some ideas using gradients combined with a variation of this method to do something along the lines you're talking about. No great breakthroughs so far. Even if something pans out, I really don't have anything algorithmic, more kind of painterly case-by-case judgement call things. If anything works out I'll definitely put it up here. My grotesquely overdeveloped ego demands it of me.

Wish I could give you more. I'm definitely working on it, though.

[Asharad]

Nice tutorial. Here is mine. No Bryce. All photoshop. I see potential with this!