Warping explained

Started by EmDee1, August 03, 2013, 06:48:09 am

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EmDee1

Can someone explain me on a very basic level how warping works? I've read about it in the Terragen Forums, but it stays to abstract for me. What I need is a simple example showing me where and what to connect with each other in the node structure. For example in a cloud layer or in a surface layer. How does a layer look like with or without a warp shader attached to it?
Besides the above question I want to express that I'm very enthousiastic about Terragen3 (version 3.0.05.0 already!) and that I'm very curious about the upcoming final release!
Greetings!
Mario

cyphyr

Well I'll give it a go. There are four types of warping in Terragen.

1/ The "Warp input shader" and "Warp merge shader"
2/ The "Fractal warp shader"
3/ The "Vortex warp shader"

and separately

4/ The Lead in warp effect>1 Octave Perlin warp on power fractal and cloud fractal warping tab.

Before I dive into an attempt at explaining these I will say the best way to find out answers to these (and any other TG question) is to set up a VERY simple scene. Create a power fractal (Perlin) with a very low octave (1 or 2) and a small overall scale so it's easy to see what is going on and apply the effect (try a Feature scale of 100, a lead in of 100, and a smallest scale of 10 to 50), and a displacement of 100. This will give you small rolling hills. Now you can apply the different warp effects and see what they do.

1/ The "Warp input shader" and "Warp merge shader"
Your shader that you want "warping" goes into the "shader" input and the thing doing the warping goes into the warper input. You could use a power fractal or an image passed through a displacement node. The greater the displacement the greater the "warp". Imagine your power fractal as an image projected onto a rubber sheet, the "warper" can be viewed as something pushing through and distorting the sheet and the image on the sheet. "If" the power fractal or image you are using as a warper was instead simply being used as a displacement then the areas where the displacement is steepest (NOT GREATEST) is where the warping is larger. So in this image of a teddy bear the white areas and black areas and areas of constant value are not warped but where there is change in greyscale value, ie something that if it was a displacement would create steepness then these areas are warped. Long winded I know but I hope this makes sense.
[attach=1]

2/ The "Fractal warp shader"
This applies a roughening of the displacement based on the slope of the area. The steeper the slope the more it is roughened. It's controls apply amount and size if the roughening. As always with terragen try some extreme values.

3/ The "Vortex warp shader"
Simple one this time, twists what ever is plugged into it about the centre defined in its dialogue. be aware that if you use more that one the following vortexes will  have their centre  positions moved by the previous vortex shaders (unless you add a compute terrain, I need to test this).

and finally :)
4/ The Lead in warp effect>1 Octave Perlin warp on power fractal and cloud fractal warping tab.
To be honest I really don't know what is going on here

Hopefully someone with a better understanding will jump in and correct my no doubt many mistakes but hopefully this will get you started.

Richard
www.richardfraser.co.uk
https://www.facebook.com/RichardFraserVFX/
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Ryzen 9 3900X @3.79Ghz, 64Gb (TG4 benchmark 6:20)
i7 5930K @3.5Ghz, 32Gb (TG4 benchmark 13.44)

EmDee1

Hello Richard, thanks so much for your detailed explanation! I'm sure it will be very helpful in understanding more of the warping technic. I'm gonna set up a very simple scene as you adviced and gonna work your remarks about the different kinds of warping into that scene. I'll keep you informed...
Greetings!
Mario

EmDee1

Hi Richard, studied on the warping effects. The first three you explained to me in your reply gave me a better understanding of what warping can add to a scene. All was very clear, the only one I couldn't get to work was the "warp input shader". But that's mainly because I didn't quite understand what to do. I took a "warp input shader" and connected as input the terrain of the scene (a power fractal shader) and as a warper an image map shader; the image should go through a displacement node you wrote... Do you mean I should connect the image map shader with the displacement node of the power fractal shader that creates the terrain? Or should I connect the image map shader with a new displacement shader and then connect that displacement shader with the warp input shader? Maybe I make things more complicated than needed, sorry for that...  ;)
Mario

cyphyr

August 05, 2013, 07:56:41 am #4 Last Edit: August 05, 2013, 08:04:27 am by cyphyr
Sorry I should have explained better. Take a look at the attached image, hopefully this will show what I mean better. If I have time I'll post a working example later but for now you should be able to work out whats going on from the two examples in the image below.

the image just shows TWO examples, they are separate and nothing to do with eachother

Actually in the second example you don't need the displacement (I always forget this!) simply use the displacement tab in the image node!)
www.richardfraser.co.uk
https://www.facebook.com/RichardFraserVFX/
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Ryzen 9 3900X @3.79Ghz, 64Gb (TG4 benchmark 6:20)
i7 5930K @3.5Ghz, 32Gb (TG4 benchmark 13.44)

EmDee1

Yes, now it's working better! I mixed things up, connecting the nodes...If you could post a working example one of these days: would be great!Thank you for your replies so far. Helped me a lot!  :)
Mario