Volumetric render tests (large pics)

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Maximus
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Re: Volumetric render tests (large pics)

Post by Maximus » 12 Jan 2012, 14:02

Hm i never been successfull with this shader, lots of parameters and is not easy at all to setup, wish this would be a little smoother to use.
Interesting images anyway :)

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gustavoeb
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Re: Volumetric render tests (large pics)

Post by gustavoeb » 17 Jan 2012, 20:26

never had the oportunity/need to use this shader. I also thought it was a little daughnting, not so much when you get down to business with it. Wish only I could know what settings would get more phisically-based vs hacky results... as this shader seems to have a lot of options and optimizations. here is a lame first image

ps: thank you for motivating us on getting our feets wet :)
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Mathaeus
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Re: Volumetric render tests (large pics)

Post by Mathaeus » 18 Jan 2012, 22:58

here's my attempt

I've tried to avoid textures at all, it seems to be hard to avoid repeatable pattern, also all these fractals aren't so fast to render, nicely to say. So, entire shape is created by ICE.
Render settings are almost default, except high quality for ray-marching ( but adaptive subdivision was disabled, set to zero), full light trace. About minute on AA 0-0, on Quad Core.

Here is simple ICE compound. Basically, it creates clouds in three steps. First step is a basic emission of just few points ( here's about 20).
Then compound emits a huge number of clones, distributing them in small tetrahedron between closest points - that's what you see in third pic. Last step is turbulence over all. Usage:
1: create empty point cloud
2: create no-simulated ICE tree
3: connect null or implicit cube ( implicit cube should be 1 unit size, for better preview). Scaling of null or cube, determines a 'bounding box' of cloud. Higher number of 'first points'
means more detailed base structure, turbulence is for small details. Compound is able to set particle color by relative particle position into tetrahedron, let's say, more transparent at border.

Image

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Zybrand
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Re: Volumetric render tests (large pics)

Post by Zybrand » 19 Jan 2012, 08:28

Wow some of these renders look very cool guys!

I have the same problem as Tekano, I can get good results for stills with this shader but not in animated scenes. Don't know if I'm just missing something obvious.
I currently working on a project where I'm trying to create Evaporating clouds and boiling clouds. Does anyone have some ideas for me on how the achieve this effect?

Thanks for the compound Mathaeus I'll see if I can get anything going that way.

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Mathaeus
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Re: Volumetric render tests (large pics)

Post by Mathaeus » 19 Jan 2012, 12:05

Zybrand wrote:Wow some of these renders look very cool guys!
Thanks for the compound Mathaeus I'll see if I can get anything going that way.
well, with this one, hardly you'll get anything smarter than usual "swimming" through the turbulence noise. As some rule of the thumb: take look at fluid flow in real world, then, if there is anything that goes backward to original flow, there is a time for some plugin, emFluid, Fury or maybe Curl Noise.
Motion should be first, when you get the motion, you choose how to shade this.

Anyway, I hope I'll find some old sequences rendered with this shader, and post them.

edit: I meant Slipstream instead of Fury, didn't know which one is simulator :)
Last edited by Mathaeus on 19 Jan 2012, 13:59, edited 1 time in total.

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Tekano
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Re: Volumetric render tests (large pics)

Post by Tekano » 19 Jan 2012, 12:53

Zybrand wrote:Wow some of these renders look very cool guys!

I have the same problem as Tekano, I can get good results for stills with this shader but not in animated scenes. Don't know if I'm just missing something obvious.
I currently working on a project where I'm trying to create Evaporating clouds and boiling clouds. Does anyone have some ideas for me on how the achieve this effect?

Thanks for the compound Mathaeus I'll see if I can get anything going that way.
yup, want that evaporating / bioling effect too, but it isn't easy! heres something that I've been trying to work out but failed to finish from lack of time & knowledge of the maths involved, from this thread here http://forums.odforce.net/index.php?/to ... ge__st__12 . here is as far as I got , rendered with Exocortex Fury though not the volume shader

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Re: Volumetric render tests (large pics)

Post by Zybrand » 19 Jan 2012, 19:36

Thanks for the advice Mathaeus it is much appreciated! to be honest my flow setups still need some work as well. We have Slipstream (simulator) and Fury for the project and they work really, sadly no emFluids but I am a fan. We are still in R&D for the effects work so I though I'd give the particle volume shader a go as well.

ha, Tekano we are after the same things, I am finding it quite hard to create. I had a look at your videos and your getting some promising results with the pyroclastic primitive aproach. I am looking through the Volumetric Methods In Visual Effects papers but most of the math there is above my head as well. In your first video Cube Powah v1 you mention that each particles color and transparency affected by the power lookup. What power lookup are you refering to and is this all you are animation or do the particles have movement as well?

My first attempts where large scale aproaches to I whole cloud system which I have gotten nice stills from in the past, but the problem is obvious with that. I just got un natural looking results that move like turbulance and not clouds.

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Tekano
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Re: Volumetric render tests (large pics)

Post by Tekano » 19 Jan 2012, 21:53

Zybrand wrote: ha, Tekano we are after the same things, I am finding it quite hard to create. I had a look at your videos and your getting some promising results with the pyroclastic primitive aproach. I am looking through the Volumetric Methods In Visual Effects papers but most of the math there is above my head as well. In your first video Cube Powah v1 you mention that each particles color and transparency affected by the power lookup. What power lookup are you refering to and is this all you are animation or do the particles have movement as well?
yeah I saw on the houdini forum that the most effective billowing example used this 'power lookup' its simply a mathematical operation called Exponentiation that uses 2 numbers one as a 'base' and another as the 'exponent' in XSI the node is just called 'Exponent' that bit is simple and I get, but the implementation into color & transparency , that credit definately has to go to BenP for his blog post here and here is a compound example for 2D lookup explaining all about it.

So I think Ive got the Power lookup working, its just the implementation of this with the pyroclastic noise is not looking so easy.
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Re: Volumetric render tests (large pics)

Post by Zybrand » 20 Jan 2012, 11:15

Yeah the power lookup you have got going on seems to work well.

The blog links for blog.ioxu.com don't seem to work (The connection has timed out, The server at blog.ioxu.com is taking too long to respond.) :( but the wiki one works fine thanks :) .
I can only work on it again on monday but I will post so videos if I get anything interesting going.

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Re: Volumetric render tests (large pics)

Post by Tekano » 20 Jan 2012, 11:27

oh. BenP's blog works here from UK fine! was going to try and make the billowing stuff work as I wanted on a sphere first before trying with more generic cloud shapes. I would definitely be up for sharing the compound once its working correctly, perhaps this may be a good candidate for a community project. Evolving & billowing clouds... certainly a useful compound!
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Mathaeus
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Re: Volumetric render tests (large pics)

Post by Mathaeus » 20 Jan 2012, 21:59

Finally I got this :) Almost the same settings RRay mentioned. Density 5000, but 0.005 for shadows, to allow translucency effect. About 3 minutes for rendering on Quad Core, AA 0-1, contrast 0.1. It seems that volume rendering don't need some heavy AA filtering, as it is already sampled by "self". Probably 0-0 might be enough. Could be problem if there is some hard surface in mix, anyway.

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Maximus
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Re: Volumetric render tests (large pics)

Post by Maximus » 21 Jan 2012, 05:44

I cant get a single result off this shader...every render i do is just horrible. can someone share some settings or some basic scene? That would be awesome..

great render Mathaeus..

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Re: Volumetric render tests (large pics)

Post by rray » 21 Jan 2012, 13:00

Hey thanks for posting tests and comments!
Here's a scn file:
VolumeShaderMeshTest.zip
(106.55 KiB) Downloaded 226 times
(needs color management to be turned on in Prefs->Display)

About the cloud billowing effect, no idea if this is actually related, but I noticed in the recent Übertage video (bottom one on this page) Holger was talking about per obj spherical coordinates in his new fractal4D shader (available for free in is BA_essentials package). It might prevent the swimming effect.
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Tekano
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Re: Volumetric render tests (large pics)

Post by Tekano » 21 Jan 2012, 13:30

Nice test Mathaeus, an interesting looks, very coral or organic. is that a single particle at the end of each strand? maybe you should try the new spherical coordinate distortion as well to break up the uniformity of each particle a little. :D
rray wrote: About the cloud billowing effect, no idea if this is actually related, but I noticed in the recent Übertage video (bottom one on this page) Holger was talking about per obj spherical coordinates in his new fractal4D shader (available for free in is BA_essentials package). It might prevent the swimming effect.
Rray, yes! that is what I tested with the 2 renders I posted on page 1 of this thread. this was immediately after watching Holger's video, I jumped on it because that is what was needed for a pyroclastic primitive, so I think that is what the displacement was used in thoses renders, the new fractal4D shader and what I assume to be spherical coordinate distortion of each particle . Again, looks great as a still, even though it rendered a long time, but as a sequence it was dreadful with colors and particles popping all over the place. I have not tried with 5000 density though! It always seems to fail when transparencies and low total cell counts across the volume are involved, and unfortunately with clouds, transparencies are pretty essential.
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Re: Volumetric render tests (large pics)

Post by rray » 21 Jan 2012, 19:44

Yes that shader needs most settings at max for something that's ok for animation.
Increasing the density makes this shader render faster luckily. Doesn't help with fluffy clouds though.

I still don't understand the whole power lookup thing. It looks like something's travedling along a magnetic field :)
Have to look a bit more into that couldn't even find a way to control the local texture coordinates per particle, that would be useful for a start.

Here's animation test with the "billowing" preset from the particle shaper:
billowing.gif
billowing.gif (532.74 KiB) Viewed 2539 times
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Re: Volumetric render tests (large pics)

Post by Mathaeus » 21 Jan 2012, 21:43

Tekano wrote:Nice test Mathaeus, an interesting looks, very coral or organic. is that a single particle at the end of each strand? maybe you should try the new spherical coordinate distortion as well to break up the uniformity of each particle a little. :D
It's Andorian anemone, everyone in universe knows it's growing exactly in this way :). No ICE strands, just evenly distributed particles - without some especial reason for that. I've tried to get a feasible render time, mainly.

As an ICE addict, I'd always try to do as much possible with ICE, of course. BA volume works nicely with huge counts of particles, also it seems to be much faster without any texture - and preview is (almost) in real time.

But this pyroclastic primitive thing, looks like some already "artistic" implementation, and people somehow likes to be happy with just one primitive. Anyway, would be nice to play with all that stuff, one day.

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