How to get started with a logo inside a fireball explosion

[Zidhjian]

Hi,

I am trying to create a scene where I have a logo come out from a ball of fire.

I have tried different options playing around with the pyro FX from the Pyro FX tab in Houdini, but there seems to be none that would give me a good starting point.

I end up having a really dull and flat looking ball and I haven't yet figured out how to have the logo inside the ball correctly.

Do I need to make the logo a static object or is there a better way?

Also I haven't really yet figured out how to get a better feel of depth in a explosion, I tried tweaking the volume, pyrosolver and the pyro object parameters, but I don't really seem to get a better visualization even after trying everything.

Also by changing the voxel size to a smaller number does not make the result that much better.

Am I missing something here?

Any tips or advice would be most welcomed!

Thanks alot in advance!

Marcus

Edited March 22, 2013 by Zidhjian

[JuriBryan]

do you have lights in your scene?

shadows add a lot of detail to pyro effects, and get rid of the flat feeling that they always have.

Also try to avoid front on shots, that never looks good with fire effects. Try to get a slight angle on it and position a light behind the effect pointing at the camera, the god rays add a lot to the interior detail

[Zidhjian]

Thanks for the tips.

I do have three lights in the scene including an enviroment light with a enviroment map HDR lighting my scene.

I really want just more resolution in the image, it looks so blurry now.

[Zidhjian]

Wich renderer do you guys use for rendering pyro FX? I read somewhere the micropolygon renderer is the most suitable for best result.

[Akabane]

Wich renderer do you guys use for rendering pyro FX? I read somewhere the micropolygon renderer is the most suitable for best result.

It depends on what you need to achieve. PBR actually gives sharper results out of the box, but of course you'll have to ramp up the pixel samples. On the other hand, you can go pretty high with the Volume Quality without detail loss. PBR works GREAT with raytrace shadows, super fast. Good thing about the PBR is you can fake fire scattering in the smoke (using a geometry light generated from the heat field) and it's pretty fast at that (opposed to the pyro shader default scattering)

On the other hand, Micropoly gives softer results, so you'll have to tweak the shader more to get sharp details, you'll have to lower the volume quality to get nice details. Working with Micropoly takes the raytrace shadows out of the question so off you go with DepthMaps.

The pros of using micropoly is that you can actually use pyro displacement, which gives A LOT of NaN artifacts in PBR.

EDIT: Everything here using 12.1 - Haven't checked if the PBR + pyro displacement still gives NaNs in 12.5 or if it has been solved, AND I still need to understand how to succesfully render out the changes created by the 12.5 Cloud Light node, which should help a lot in faking scattering. It does in the viewport at least. If you want to play with it remember to isolate the density field for the cloudLight, otherwise it'll calculate it for EVERY field you have. But as of now (been playing with it 10 mins) I still am not able to render it correctly (whenever I use the Ce Vector field as emission in the pyro shader, render goes crazy)

Edited March 25, 2013 by Akabane

[Farsheed Ashouri]

Please upload your hip file, so we can improve it.

[Zidhjian]

Thanks for the tips! I will start a new project from scratch to get a little bit clearer result to begin with, I'll send you the file when I get to the "I need Help" point. =)

[Zidhjian]

Hi, Here is an test file attached of a new fireball test.

I couldn't get this to look sharp in the renderer, maybe you can? =)

Fireball.hipnc

[Zidhjian]

Here is an example I did with Billowy smoke.

Same problem, can't seem to get a sharp render.

[old school]

Use temperature field instead of density for smoke in both the Smoke Object DOP's?

Have a look at this thread I just posted for more info:

http://www.sidefx.co...p=130164#130164

Density is pretty much guaranteed to go from 0-1 in all simulations and that it makes for a good mask inside of pyro.

The problem with the density field is that for most sims, it is either off 0 or on 1 and the transition is that blurry kife edge thin band that is hard to get around.

Temperature is this nice gradient from 0 to whatever your temperature is. In the default sims it is pretty much guaranteed to go from 0 to about 9 and up. You need to know the bounds of the temperature field which can fluctuate from sim to sim. Use the Smoke Object DOP visualization settings viewing temperature and adjust the max range until all the white is but barely gone. That's your max temp. Use this value in the max value in the fit range prior to munging with a ramp to really sharpen the border.

Instead of fighting soft volumes, you are fighting aliasing because you can get it way too sharp. Then you add some noise to combat the aliasing...

So I tried to create the crappiest billowy smoke sim but use temperature and render a pretty crisp and very dense volume. Then in the pyro shader, add some very high frequency noise to polish the turd.

Both nice and crisp with lots of detail on top of a low res crappy sim. Mind you the calculation and rendering of the noise slows down the render a bit but what do you expect on such a low res volume with such high frequency detail...

See the example file attached.

billowy_smoke_sharper_using_temperature.hip

[Filipp Elizarov]

Thank you so much Jeff =)

[Zidhjian]

Haha looks almost like a frosting on a cake.

I will definitely try out that technique.

BIG thank you!

After joining this forum I have learnt more than i've done in one year boggering about in Houdini.

I'll send you some pics after i'm done with this sucker.

[Zidhjian]

I encountered another problem. I can't seem to get the fire to look like fire, it looks really like it was drawn. Any tips/starting point on how to get a realistic looking fire with the Pyro Shader?

[Zidhjian]

Here is an example done with the flame shelf tool. I tweaked the opacity in the shader a bit on the fire side and recolored the smoke darker, added some more shadow density and made some noise in the volume. I added one light and a volume light aswell to the scene. This is not a very good render but you get the idea.

[Zidhjian]

So, any tips on this matter?

[shushu]

I think it depends on the context ... That is, the elements of the scene and how they want to give the right emphasis. Is not the same an explosion in the interior of a room, that one which is completely different in an outside, and thereforeshaders tips.

v

I've seen a lot of 3d explosion testings, and probably because of the ease of use of the tools, we get lost easily. What do I show? Response to this might be: what else can not be make in other systems that can be make with 3d? Probably could be a good start. There are a lot of things that can not be made with footage

In real life when you want to blow up something with a bomb.

One prepares a bomb in the proper context...

What happens when you light the wick? What happens when the burning wick reaches the explosive? Was it what you expected ?. If it was filmed, or made with simulations, how these cases could show? .

I imagine two cases: an explosive popping a stone and then a logo is created by fragments flashing ... etc.. And a grenade made by trolls exploited in a person's face.(In the movie, men vs trolls.)

in the second case the thing can be show cheerfull, not, however,in the first.

Edited April 4, 2013 by shushu

[Zidhjian]

Yes of course it depends on the context, but I just need a starting point to start from, and some tips on how to tweak the shader.

[shushu]

well.

tips: do not forget that the light sources are very important.

And there are tons of information on how to work with lights and replicate the same techniques with Houdini ...

all grenade explodes all similarly until somebody to put something close and the picture changes completely.

density. 0.1,1,10,100

I think the first might be, smoke cigarette, not yet a nuclear bomb.

Edited April 6, 2013 by shushu