Advice on cloud scene

[johnsonmax]

Hey guys,

 

I'm fairly new with Houdini, and I was wondering if I could get some advise on how to create this cloud effect.

 

http://cdn.londonist.com/wp-content/uploads/2014/03/london-mist-800x321.jpg

 

I've been playing around with the Off the shelf clouds but they not getting me the right look. Is it possible with the Off the shelf cloud tools? 

 

Thanks

 

[iamyog]

If you create a cloud via the shelf tools, you basically lay down 3 assets :
- the first one convert your geometry into a volume
- the second add some position noise
- the third takes care of the lighting

What's interesting for you here is the noise. Even though it changes the global shape, it does not affect the density. It means that you probably ends up with a linear ramp of values between 0 and 1.

You want to add some noise to variate that. A volumeVOP might help where you modify the input density via some noise functions.
According to your ref picture, you're aiming for quite low density values, that means your render times will increase a lot and a search on the forum will bring you answer on how to control that.

 

Use a volume slice to check the density in your volume.

 

I'm not sure that using the cloudFX shelf tool is really helpful in your case. It is good to quickly create single beauty clouds but it don't think it is the most efficient way for the look you're after.

Edited January 13, 2015 by iamyog

[johnsonmax]

If you create a cloud via the shelf tools, you basically lay down 3 assets :

- the first one convert your geometry into a volume

- the second add some position noise

- the third takes care of the lighting

What's interesting for you here is the noise. Even though it changes the global shape, it does not affect the density. It means that you probably ends up with a linear ramp of values between 0 and 1.

You want to add some noise to variate that. A volumeVOP might help where you modify the input density via some noise functions.

According to your ref picture, you're aiming for quite low density values, that means your render times will increase a lot and a search on the forum will bring you answer on how to control that.

 

Use a volume slice to check the density in your volume.

 

I'm not sure that using the cloudFX shelf tool is really helpful in your case. It is good to quickly create single beauty clouds but it don't think it is the most efficient way for the look you're after.

 

Thanks iamyog, I was actually trying to volume with VOP, still messing with it now.

 

I was thinking I could play about with a very slow smoke sim, thin it out and see how it would look like. Think it will work? 

Any other solutions come to mind to create that sort of look?

[kev2]

I think you could get a solid hero cloud (screen left in your shot) and use the smoke tools to achieve the low density clouds (screen right). The low density will exhibit motion more than the hero which probably shouldn't move in this perspective (unless motivated by something in a prior shot).

One thing I would add to iamyog's suggestions is try a variety of source geometries. I get very different clouds based on different source geo (same for pyro). 

Good luck.

[teratera]

According to your ref picture, you're aiming for quite low density values, that means your render times will increase a lot and a search on the forum will bring you answer on how to control that.

 

Care to help finding those threads? Or any advice is good too. Really wondering if there's something else to this than Volume quality and Transparent samples. Thank you.

[iamyog]

old school exhaustive really good explanations : http://forums.odforce.net/topic/6143-how-do-i-optimize-my-volume-lighthing/#entry40892

Some other tips by Peter Claes : http://forums.odforce.net/topic/15440-rendering-on-a-budget/#entry95194

[khedkarsanto]

Hi 

johnsonmax,

 

I can help you out with this,

 

There are couple of  ways to achieve the same effect which you have specified in the image.

 

I prefer openvdb method.

 

steps.

1. Create a simple box with some height, width and length as you want.

2. Convert it into openvdb(density).

 

Now ther are two ways with which you can add noise ( or pattern ) in it.

* Using Volumevop in SOP level.( takes very less time to render)

* Using Noise at shading level.( takes long time to render)

 

I will upload a scene file once I get free from my work, mean while you can try.

[johnsonmax]

Hi 

johnsonmax,

 

I can help you out with this,

 

There are couple of  ways to achieve the same effect which you have specified in the image.

 

I prefer openvdb method.

 

steps.

1. Create a simple box with some height, width and length as you want.

2. Convert it into openvdb(density).

 

Now ther are two ways with which you can add noise ( or pattern ) in it.

* Using Volumevop in SOP level.( takes very less time to render)

* Using Noise at shading level.( takes long time to render)

 

I will upload a scene file once I get free from my work, mean while you can try.

Hi khedkarsanto,

 

Cheers for the help, trying that out now.

 

Thanks

[borbs727]

Hi 

johnsonmax,

 

I can help you out with this,

 

There are couple of  ways to achieve the same effect which you have specified in the image.

 

I prefer openvdb method.

 

steps.

1. Create a simple box with some height, width and length as you want.

2. Convert it into openvdb(density).

 

Now ther are two ways with which you can add noise ( or pattern ) in it.

* Using Volumevop in SOP level.( takes very less time to render)

* Using Noise at shading level.( takes long time to render)

 

I will upload a scene file once I get free from my work, mean while you can try.

 

Hi Santosh,

 

I'm pretty new to Houdini, could you elaborate on this process or post a HIP?  I'm not sure how to convert geo to openVDB or what type of settings to use in the volume VOP.