Standard fractal cirrus clouds are nice and all, but still don't have that dramatic sweeping flow that real cirrus tend to have. I've been working on a some new methods to pull this off and finally made some progress. I've been using the apline fractal shader to warp standard power fractals, and the results are looking spectacular.
Still more work to do, but its getting there.
Bary n-i-i-i-ce. ;D
Care to share your methods?
Very sweet (and useful) was this what you were looking for your gray scale extraction for?
richard
Quote from: calico on November 19, 2008, 12:35:26 PM
Bary n-i-i-i-ce. ;D
Care to share your methods?
Yea, as described above, take a standard power fractal (scaled appropriately of course), and then warp it with a warp shader, using the displacement from an alpine fractal (scaled appropriately). The alpine fractal will be the "warper" and the PF is the shader. Make sure displacement values for the alpine fractal are in the 10000 range since a cirrus layer is higher. Might take you some time to dial it in just right, but they look great. I have another version which looks even better (at least on the sample render). One trick is to use a redirect shader just after the alpine shader so some of the warp effect is on the X, or Z axis, to give that "flow" effect.
Quote from: cyphyr on November 19, 2008, 12:37:48 PM
Very sweet (and usefull) was this what you wrer looking for your gray scale extraction for?
richard
Cyphyr, yes, its one of the many reasons, as cirrus clouds look just like a 2d erosion map. I just want a procedural one so I don'thave to use image maps. I am currently testing an image map (heck, I might try the one you posted) :)
Just ran a test render using Cyphyr's alpine grayscale map image he posted. I had to tile the image using Photoshop for no seams. Additionally, since its an image and not procedural, the resolution and detail is limited, so I had to rely solely on the alpine fractal's detail settings to break up the image somewhat. It helped, but you can still see the limitations in using images, such as softness and flat color. A procedural method is the way to go for ultimate detail.
I think your first version is way better :)
However the image I posted is only very low res (just to show the principle), maybe something could be done with a better image. That said one advantage of using a procedural method is that it could be much better manipulated/distorted with further functions.
Good find
Richard
Yes, I am trying to get away from image maps if at all possible due to the resolution/detail limits. Many thanks for your input on this. 8)
Cool,something new to play with.Thanks for the inspiration. ;D
Very nice results!
nice work! could we please get a node network screenshot?
I love the new detail in your first render...
Pretty easy setup, you just have to think of using the alpine fractal.
Had a play with adapting my model to your idea. Because the distribution shader is based on elevation, a) the alpine fractal has to be able to reach the cloud layer and b) the altitude restriction should also include the cloud's altitude.
very interesting results!...more food for thought!
BigBen-
That looks superb! 8)
Thanks moodflow... another result for the forum approach.
Apart from the scale/displacement settings of the alpine fractal, you can tweak the degree of warping by adjusting the colour of the distribution shader.
Just keep in mind that the Alpine Fractal is probably the slowest of all the shaders in TG2, so don't use this for volumetric clouds unless you're some kind of masochist... :)
Have you tried using a Power Fractal displacement for the warper instead? Might be able to get similar results with quicker renders.
Matt
That thought had crossed my mind, as the slow down in the preview is quite noticeable. Here's a comparison with a plain fractal and the unwarped cloud density shader (screengrabs to include the render times). Without any surface shaders and only one cloud layer, the simple PF is about 4X faster than the alpine fractal.
Having a bit of a play with this model and 3d clouds. Swapped the Tex coords with a compute normal and then added a visualise normals node. Add a transform shader immediately below both fractals. Animate the warping shader downwards (direction is possibly irrelevant), and the cloud density shader upwards... looks promising so far for some very effective animations.
I took Big Ben's tgd and wedged some parameters.
variation method and noise flavour.
I think noise = ridges, mix1 and variation = multifractal variants are looking promising
(I had to over compress slightly :( to get it to fit in 512K but you can see pretty well)
Cheers...
Interesting comparison. That'll save us a bit of time ;)
Animating the displacement offset in the pf shader also seems to give nice animations.