Hurricane/tornado

Started by Alfamike, January 21, 2008, 09:56:38 PM

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Cyber-Angel

Sorry to go way off topic but would these techniques work for terrain as well (Wild I know) you might get some vary unique spiral shaped terrains with this (or it might not work at all) might be fun if some one has time?  ;D

Regards to you.

Cyber-Angel

dhavalmistry

Quote from: Cyber-Angel on January 27, 2008, 09:09:54 AM
Sorry to go way off topic but would these techniques work for terrain as well (Wild I know) you might get some vary unique spiral shaped terrains with this (or it might not work at all) might be fun if some one has time?  ;D

Regards to you.

Cyber-Angel

it should work if you use displacement shader....


and very nice work AM....this is turning out to be a real goodie!
"His blood-terragen level is 99.99%...he is definitely drunk on Terragen!"

Tangled-Universe

Quote from: Cyber-Angel on January 27, 2008, 09:09:54 AM
Sorry to go way off topic but would these techniques work for terrain as well (Wild I know) you might get some vary unique spiral shaped terrains with this (or it might not work at all) might be fun if some one has time?  ;D

Regards to you.

Cyber-Angel

Sure, if it works on the water plane shader it works on the terrain as well.

Tangled-Universe

Quote from: dhavalmistry on January 27, 2008, 09:22:44 AM
Quote from: Cyber-Angel on January 27, 2008, 09:09:54 AM
Sorry to go way off topic but would these techniques work for terrain as well (Wild I know) you might get some vary unique spiral shaped terrains with this (or it might not work at all) might be fun if some one has time?  ;D

Regards to you.

Cyber-Angel

it should work if you use displacement shader....


and very nice work AM....this is turning out to be a real goodie!

Ghehe, 10 sec. earlier than me ;D

j meyer

Hey Mr.L. that's excellent!Can't wait to have a look at your file. ;D

rcallicotte

This is very good, Mr. L.  Hope you share.   ;D
So this is Disney World.  Can we live here?

Alfamike

Quote from: Mr_Lamppost on January 27, 2008, 07:56:44 AM
Here is the first test rendered with any real quality of my procedural hurricane set up. There is some work to do yet.

The node network is a total mess at the moment I will go away and tidy it up before posting  ;D


Hey Mr_Lamppost, that's a great spiral you've got there.

I think my attempts at getting heights in the spiral are not going anywhere at the moment, but am still sticking with it for a while.

Hope to see a tgd or clip of your work here some time.

Good luck.

AM.

Mr_Lamppost

As promised here are the tidied up nodes and tgd.

As stated previously I have not looked in any detail at the previous methods; not because there is anything wrong with them, the results look interesting just different from what I had in mind and I wanted to follow my idea through without getting sidetracked.  A while ago I had posted a first thought on how a procedural hurricane could be made in a thread started by nvseal:

http://forums.planetside.co.uk/index.php?topic=3116.15

I have more or less followed this reasoning although I have had to modify things a bit because there doesn't appear to be any way to manipulate the integral Get Position of either a Power Fractal or cloud Density Fractal. 

The first step was to come up with a function that would start at zero, rise quickly to a peak then falloff slowly to zero again.  I ended up using the combined result of two functions (I have included a POV render of a graph showing these). This falloff function is used in two ways, firstly as a control for the density of the clouds and also to vary the amount of twist with distance from the centre.

I ended up using a simple Perlin noise function for the large features because I could get at and distort the output from the Get Position.  What I am doing is using a Get Position, rotating the output around the origin by an amount controlled by the falloff function as applied to the distance from the origin; there is also a control for the overall amount of twist.  This modified point is then passed to the input of the Perlin 3D Scalar.  I have included one of the tests showing this distorted Perlin used as a colour blend controller.

The final step is to take the output from the (Distorted), Perlin 3D Scalar, multiply it by the falloff function so that the hurricane is dense towards the centre and more wispy on the edges. This is then used as the Mix Controller for a Merge Shader merging a normal cloud Density Fractal and a constant zero (Clear sky).  The falloff function is also added into this density controller and the combined result passed through a Colour Adjust, these additional steps kept the hurricane confined without the whole thing going wispy.

I have marked the main controlling nodes in the diagram.

Last but not least the tgd have fun   ;D
Smoke me a kipper I'll be back for breakfast.

moodflow

Woah, this is incredible work all.
http://www.moodflow.com
mood-inspiring images and music

Alfamike

Hi Mr_Lamppost,

That's a great function, the way you've set up the control parameters. Still got to figure out an easy & customisable way to get heights in there.

I noticed the way you've built your spiral. You might want to have alook at changing the way you build your argument for the rotation. For my logarithmic-like spiral I worked this out.

Compute the distance from GetPos to the centre of the spiral, plug that into the input of a PowerScalar and then put a ConstantScalar into the other input. Plug that output into your sin and cos arguments. Play with the ConstantScalar values.

Maybe this speeds up your rendering, maybe not.

Great post and thanks for the TGD.

AM.

Mr_Lamppost

There are a few things that could be improved

I have already been looking at using a power of the distance from the centre to drive the density curve as a way to make the eye bigger.  Having the functions set up in a POV-Ray scene lets me very quickly make changes and see the graph of the result.  Once I have a result I like I can then build an equivalent node group.

There may also be some merit in using different functions for the rotation and density.  I used the same function for this test as they both needed a similar curve and it saved on the number of nodes, now they are more organised adding a second function shouldn't be a problem.

I am also looking at ways of adding roughness to the Perlin. 

I am not sure how vital this is but it may be worth adding the ability to set an arbitrary centre.  The hurricane can be positioned by adding a transform shader to the cloud layer but it would be neater to have this as part of the hurricane.


I noticed that Cyber-Angel asked about applying these functions to the terrain.

Hurricane Island  ;D
There is some fairly extreme displacement there so the shadows are mush but I kind of like it.
Smoke me a kipper I'll be back for breakfast.

rcallicotte

Wow.  Great work Mr. L.  And thanks for the instructions.
So this is Disney World.  Can we live here?

j meyer

Great,thanks Mr.L.!

Did some tests with AM's file as displacement and got some nice
crashes and peculiar render behaviour.Couldn't figure out why though.

Alfamike

Quote from: j meyer on January 27, 2008, 05:43:46 PM
Great,thanks Mr.L.!

Did some tests with AM's file as displacement and got some nice
crashes and peculiar render behaviour.Couldn't figure out why though.

I have only applied it to a watershader and cloud density. I have played quite a bit with the function nodes (apart from puting them into a displacement shader) but TG never crashed. I'll have a try later.

AM.

Matt

Quote from: Alfamike on January 25, 2008, 09:15:53 PM
Maybe Planetside can let us know for sure whether this vertical cloud density shading is (im)possible as a direct input into the Cloud Layer Density? 'Cause I'll keep at it for a wee while longer.

The density function is 3D; functions that use the Y component are perfectly acceptable and variation along the Y component is certainly possible, even if it is not very easy to see whether or not it's working. Just make sure that your positions are derived from "Get position in texture".

Matt
Just because milk is white doesn't mean that clouds are made of milk.