Exclusive New Device Sneak Peek

Alpha-2 went out to the testing group late last week. The GUI is getting closer to final quality, although there’s still a few huge things left to get done.

Functionality-wise, for Pro there is of course a slate of new devices that will make an appearance. I want to talk briefly here about one of the more exciting — and fundamental — ones.

The Spectral Combiner

The Spectral Combiner has multiple purposes. I’m going to talk right now about the first purpose (which is actually arguably the lesser purpose): as a very powerful companion for the regular Combiner.

Essentially, what the SC allows you to do is mix and match two terrains on a frequency basis. The best way to think of “frequencies” in a heightfield is that low frequencies correlate to slow, rolling changes in the terrain, whereas high frequencies are the sharp detail of the terrain. The SC allows you to average together the input terrains differently for different frequencies. The concept can be a mind-bender, so a better way to understand it is to look at the example image below and follow along.

(Click the thumbnail for full image)

Source A is the the result of some quick sketch lines I drew in Layout mode to create a mountainside. It looks roughly like a mountain but is certainly lacking in realism.

Source B is a perlin “billowy” style fractal.

The Spectral Combine A+B image shows you the result of a combination that draws from Source A for the low frequency data, but brings in Source B for the mid and high frequencies. The result is a terrain that follows the guiding contours of Source A, but has the details of Source B — it’s as if the major “mountain lumps” in source B just happened to be in the exact shape we specified. It’s a little hard to notice in this reduced size image, but the ridges of the mountain in Source A have been specifically damped out and are no longer razor-sharp, and won’t cause the dreaded “sawtooth” aliasing along the ridges.

With a little bit of erosion, the end result of the drawn sketch shapes is a quite realistic mountain! And even with this we started with a pretty crude approximation to a mountainside — with some tweaks to Source A it would be another leap better yet.

How is this any different than a normal combiner?

Check out the images of the normal combiner set to “multiply” mode, and the eroded version. The result isn’t really anything like what we want. You can pretty easily see that Source A was simply masking Source B. Areas that are low in Source A are low in the result, but areas that are high aren’t necessary high — our gradually increasing slope moving up the hillside is lost. Using “average” mode doesn’t fix the problem, and neither does erosion.

This is just one of the uses of the new Spectral devices. There are several other exciting things you can do with the control it gives you. I’m not going to tip my hand just yet though. 🙂

8 thoughts on “Exclusive New Device Sneak Peek”

  1. I find myself in the need to make a river: to allow all the drool build-up in my mouth to flow out, and leave a pleasant breath, so I can start chewing on that device, as well 😀

  2. Lovely! Is it possible to specify a real DEM as one of the sources? I’d be interested to see just what you could do with this…
    Like you say, with a bit of extra time with the original layout, the output would improve again. 🙂
    -and rivers, simply invert the layout method- I can see we’re going to have a lot of fun with this.


  3. No fair, you’re telling all the fun secrets in public first now. 😀

    I think this device is along the lines of something I’ve wanted for a long time now but couldn’t really articulate. Very promising indeed.

    – Oshyan

  4. I think Monks if you look neat the center of the “spectral combiner a+b and erosion pic you will see your glacial cirque, it is really close to this, http://pivin.com/davidsr/cruise/Album18.html, ( which is the Atahbascan glacier,I think. Just a good pic I found surfing). I can see headwalls and hanging valleys being easier to produce with this. SeerBlue

  5. I think I can see where you mean- on the right, there are a few examples, one especially good U shaped valley top rightish.


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