Rectangular Noise

[Dune]

You should use the colors for displacement only, Michael, not as a child with the colors. And as you see from your sample, even a straight noise isn't straight in the terrain. A small patch szie in compute terrain certainly helps (I needed that in my winding river as well for the strata), and adding more compute terrains, compute normals, and XYZ shaders, also helps, but I'd like to minimize them for the reason Martin wrote; takes more time to render.

But you could look at the problem as needing to push a slanted surface horizontaly to become more verticle in steps

That indeed is the hard part!

Here's some of my results at testing...

[Oshyan]

I think square rocks_1okt14_v1var1-4.jpg is really excellent all around, square noise background cliffs and foreground too.

- Oshyan

[choronr]

Agree with Oshyan, in real life, I have seen these types of rock faces in places in Arizona and Utah ...they are spectacular. Love your images Ulco, especially the first one.

[TheBadger]

Yes I agree with Oshyan. That image is nearly perfect. I don't think the waving line is natural looking though. But in your last image the hard strata line is really good. There is some nice subtle details in the last image.

On image 1 above on the far left side, the rocks get a little crazy. Whats happing over there?

Nice work ulco! Nearly there!

[Kadri]

That rock structure in the first one looks good really.

[Dune]

On image 1 above on the far left side, the rocks get a little crazy. Whats happing over there?

That's the problem with the square noise, it works best on one angle. Easy if you have a north facing wall, just stretch the fractals or blues in Z.

[TheBadger]

Ulco,

What about the image you posted where the snow was only on one side of the hill. Would it be possible to attach the noise to that set up, once for each direction (N,S,E,W so four copies of the noise) and then have the rectangle head in the direction while limiting them by slope. Could that be a fix to the angle problem? Or just new problems?

[Dune]

That's what I did, but it's still not perfect.

[TheBadger]

That's what I did, but it's still not perfect.

LOL OK, time to re read all of this thread now.

...

"...still not perfect"
Perhaps adding the same in the NE, SE, SW, NW, so eight noises by your method? I am guessing that would be very slow to render even if it worked though?
Its an interesting problem, but I have to say Im still pretty happy how far this has gotten!

[Dune]

I divided into three directions.

[Tangled-Universe]

This took only 2 PF's (perlin), then some not so complicated tricks with slight warping and conditional blending.

The main trick is, like we're discussing now, how to apply this to a terrain in such a way that it looks nice regardless which direction the steep surface is facing.
This just on flat ground, for example, so getting it work on a vertical wall will probably be quite challenging.

I still have the feeling TG isn't fully 3D in this regard, but rather 2.5D at best.
The stretching and angle-dependent aspects we're discussing wouldn't happen when the noise is interpreted in full volumetric 3D, instead it shows clear resemblence to mapping a flat texture over an irregular surface, causing these issues.

[Dune]

Rightly spoken!

If you keep the white of the pf's clamped you can get flat rectangles and with some additional displacement can get you a long way, but it needs a good 'horizontal way'.

[Tangled-Universe]

Ulco, the noise was already clamped, but it was a nice idea to clamp them further
You should be quite careful though, because the effects can be very strong and quite devastating if you overdo it.

[Dune]

Yes, but if you add another fractal or warp a bit, you can overcome these sharp edges. And some rocks are VERY rectangular and hard edged. Now if you raise the amount of white, you get narrower cracks and more rock. Lots of possibilities, but my main wish would be to displace a (let's say 45º) angled slope (into any direction) into straight vertical blocks......  that would be quite something!

[Tangled-Universe]

I think I see what you mean.

This setup works best if if I adjust the offset of the PF's as well as a bias function down stream.
Manipulating the white color of the fractal changes the range of values for the whole function and thus I would need to re-adjust the clamping values. I don't like that.

The idea is to have this setup as easy as possible.

With that in mind I would really like to have the option in the transform node to rescale displacement amplitude.
This function uses 10 displacement shaders, each having a different displacement factor which is relative to the scales of the base noise.
It's all inter-linked/tied up to each other.
Now, if I would like to re-adjust the scale of those 2 PF's I'd need to calculate and alter the correct displacement values for those displacement shaders. Oh, and also for the 2 fractal warps.

Why do I need to work so hard to have TG do what I want? I wish we had easier tools for this like extra functions in the transform node, but a macro-approach would be ideal.