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shiv_d

Cloud FX for Rolling, Evolving Cloud

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Hi Everyone!

 

Greetings from Toronto :)

 

I am trying to do rolling clouds that evolve sideways as they move. Here is the reference:

 

 

Have to make it look photo-realistic.

 

I tried the Cloud FX tool but it does not give me the nice rolling motion that Pyro sims do although the former does give me really nice detail.

 

I am trying to find a happy middle ground. Can someone tell me how I can upload zip files

 

Your help on this would be much appreciated!

 

We are still in the R&D phases of production.

 

Thank You.

 

Regards,

Shiv

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Sidefx added the 'Sky Rig' shelf tool which creates a setup much like that in your video, it renders with cvex, so I would rely more on the render preview than the opengl preview. It allows for 'evolution' of the noise pattern which for the most part does a good job, it takes some tweaking.

 

If you wanted more control or smoother motion you can always create something similar with vops, you could even use the skyrig system to create the initial volumes then in a pyro simulation you could add to the density field with a fast dissipation rate which should give the illusion of smoothly changing clouds.

 

-Nathan

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Thanks for the prompt reply Nathan, I appreciate it! :)

 

I see what you mean by relying more on rendering with Cvex than the OpenGL preview. I am making my own Vops utilizing cvex with rotation matrix and multi-step displacement.

 

How do I add to the Pyro sim density field though, by using it as a fluid source?

 

I am utilizing dissipation, disturbance and turbulence at the moment.

 

Regards,

Shiv

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Ok, I am getting really nice results with Cvex Generated Volumes but I am getting a lot of noise jitter on the fine edges / areas of low density. Any tips on how I can get rid of them? Increasing the volume sampling doesn't do it.

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I am also doing some R&D on the sky rig and I find that increasing volume quality in mantra or transparent samples worked for mine? Could you share a hip file if it is convenient? Thanks!

 

-Darren

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Hi Darren,

Thanks for the prompt reply, I appreciate it!

Unfortunately, I am unable to share the hip file since it is for production. Is there a way to reduce noise jitter in the OpenGL preview? I am not using the sky rig. I am creating my own volume vops using aaflow noise and a few math nodes.

Thank You.

Regards,

Shiv

----

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Hi Shiv, 

I understand :D  just thought that you might be able to share an example file but it's all cool! 

 

Pardon me for my lack of knowledge of OpenGL, when you mean opengl preview do you mean using the OpenGL ROP?

 

About how you did the volume vops, from what I infer, you used a cvex shader? If so, the jitter is most likely caused due to your render settings? Not too sure though, but for the case in mantra, the render settings affected my noise alot.

 

Sorry if my information was not of any help :mellow:

 

-Darren

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Hi Darren,

 

No worries, I'll try to prepare an example file :)

 

By OpenGL preview I mean in the view-port.

 

The jitter is happening in the view-port, I haven't rendered it yet.

 

Thanks!

 

Regards,

Shiv

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Hi again, sorry for late response, notifications were not being sent to me of your replies :( !

 

CVEX is directly related to volume quality/samples so increasing transparency samples and volume quality will have it looking better, you can also try adjusting the volume filter on the geometry object to give a little bit softer of a result. Also keep in mind you can run the cvex on any volume, so you could always read in the density of your pyro sim and apply your cvex noise to it.

 

-N

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Hi Darren,

 

No worries, I'll try to prepare an example file :)

 

By OpenGL preview I mean in the view-port.

 

The jitter is happening in the view-port, I haven't rendered it yet.

 

Thanks!

 

Regards,

Shiv

 

 you might try looking at what your maximum 3d texture resolution is set to (in display preferences).  If it is much lower than the actual size of your volume you could get artifacts.

 

 -G

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Hi again, sorry for late response, notifications were not being sent to me of your replies :( !

 

CVEX is directly related to volume quality/samples so increasing transparency samples and volume quality will have it looking better, you can also try adjusting the volume filter on the geometry object to give a little bit softer of a result. Also keep in mind you can run the cvex on any volume, so you could always read in the density of your pyro sim and apply your cvex noise to it.

 

-N

 

Thank You Nathan, I'll keep those things in mind for the render. I see what you are saying about running the CVEX on any volume and by reading in the density in the pyro sim and applying the cvex noise to it.

 

However, there are a few caveats:

 

1. I wish to fix the noise / jitter in the viewport, so that would be the OpenGL display.

2. To get the same result in the pyro sim is a challenge. For the evolution of the clouds and the rotation, one would need to reproduce conditions such as temperature and atmospheric humidity. Rolling motion can be caused by the process of cooling down of hot gas. At the beginning, gas rises due to high temperature and buoyancy force. As it begins to cool down, gas starts to descend under the influence of the gravity force.

3. The other way is by using external forces like vorticles etc.

Edited by shiv_d

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Without an example, it is really quite hard to say how to improve especially if you created the cloud yourself, it is even harder to tell :\ 

 

Anyway just a few things I would like to mention, since your simulation is done by a cvex shader, the viewport and render may differ alot, thus it would be better if you just render a short sequence of perhaps 10 frames? 

 

I find that the sky rig tool in Houdini was really well done and you might want to consider to study how they built it and integrate with yours for the motion, I have gotten some pretty nice rolling animation just by animating a few of the parameters.

 

Let me see if I could post up a few of my test renders back in work tomorrow~ 

 

-Darren

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Here is my cloud animation, evolving and rotating.

 

As you can see, I am getting nice feather-shaped tendrils, organic rotation and evolution of the noise, appearing and disappearing.

 

Thanks for watching!

sd_cloudTestDynamic_v016.mov

post-11156-0-33335900-1410371703_thumb.j

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How can I get the clouds I did above to elongate(scale) as they move towards screen right while still preserving the resolution of the cloud?

Edited by shiv_d

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Hi Shiv,

 

Here's a render in HD from what we worked on so far. I will upload an alpha version soon after its rendered.

 

 

I think you can try playing with noise in your cvex shader, that might help

Edited by dszs

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Thanks for the test Darren, I appreciate it!

 

Unfortunately, my client's needs are very specific.

 

Here is another version I made with elongation, unfortunately, a lot of jitter is visible. I think it is something to do with high band aanoise in the volume vop.

 

Regards,

Shiv

sd_cloudTestDynamic_v018.mov

post-11156-0-25139500-1410446001_thumb.j

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Hi Shiv, for some reason, I can't open your .mov files can you upload a video sharing web or re-upload a different format. Sorry for the trouble! 

 

-Darren

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How did you animate the noise? I faced a similar problem once and the problem was the my noise offset was too fast, I changed it to $T and it was gone. Perhaps you could try?

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How did you animate the noise? I faced a similar problem once and the problem was the my noise offset was too fast, I changed it to $T and it was gone. Perhaps you could try?

 

I am using aanoise, the Flow attribute is set to $T / 400

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