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Ubermatik
03-01-2011, 04:47 PM
Hiya guys, I was wondering if you could help me out. Basically, I'm trying to mimic 4 elements (earth, stone, water and fire) as a simple render for a project I'm working on. I'll let you see what I mean with the attached picture, but basically I've hit a bit of a rut. I'm happy with the first 3, but I'm having a little trouble with the fire element. Each one is formed into a kind of sphere, yet so far my Fluid FX attempts with flames and fire have failed to mirror that approach. I need to figure out how to 'wrap' the particles around a poly sphere similar to the size of the others. Would I need to emit the particles from the poly sphere, and then link that emitter to the Fluid FX? If so, how would I do that?
So far, I've only been able to make a collision so the flames spread across the bottom, but yet they don't reach the top (or I've made the fluid container too big and the flames have been much higher than ideal).

So yeah, I'm seeing if there's a way to create a kind of 'fireball', where a flame wraps tightly around a poly sphere (with maybe a stone or lava texture) and then extends upwards.

Here's the picture of my results so far anyway, and my failed fire attempt too:

http://img839.imageshack.us/img839/3342/elements6.jpg

http://img40.imageshack.us/img40/2684/failedfire.jpg

Also, it would be nice for the fire to have more of a flame effect instead of coming to a straight, single peak. It seems more like a candle flame at the moment! Can anyone provide any tips on that?

Thank-you in advance!

Duncan
03-01-2011, 07:31 PM
Use turbulence on the fluid emitter to get a less uniform emission. For fire the turbulence speed usually needs to be high. As well you may need to increase the frequency.

With the solve use highDetailSolve and increase temperature turbulence for more detail and temperature buoyancy for greater height. You may wish to emit from your sphere (fluid emit from object) but have a slightly smaller sphere inside that you use for collisions.

Duncan

Ubermatik
03-01-2011, 08:30 PM
Thanks! I now have a much better wrap-around effect, and the fire seems more like it's eminating from the sphere rather than passing through it. Despite adding turbulence, however, I still have a single solid flame, instead of several 'tongues', if you get me? Here's my result so far:

http://img641.imageshack.us/img641/3527/improvedfire.jpg

As you can see, the fire rests closer to the sphere, which is spot on, but the flame is still too collected. I'm looking for an effect more like this:

http://www.sg-training.org/fire.jpg

When you mentioned the turbulence being high, how high do you mean?

Thanks again, your help is much appreciated!

mandark1011
03-01-2011, 08:52 PM
try adding more detail turbulence to your emitter.
Looks like you will need more voxels in your grid that is why your are getting such a low resolution single flame.
Also play with heat dissipation that'll help with creating more tongues as heat tends to find a centralized core that it will emit up once the fluid is normalized.
Boundaries should be set to x and z closed _y closed y open.
velocity swirl will help too.
forward propagation (maya 2011) will help too

cowboy71
03-01-2011, 08:56 PM
In order to get the fire licks, you have to increase the bouyancy and turbulance. Fire is one of the harder things to achieve with fluids. The settings are very touchy and it just takes some trial and error to achieve the type of fire you are after.
http://www.vimeo.com/9163048 This is a fire test I did awhile back, and I had the bouyancy cranked way up there. I also had a volume axis parented to the emitter. I find using a volume axis to create turbulence works great.

Aikiman
03-01-2011, 09:09 PM
Dont forget to include it in reflections :)

Duncan
03-01-2011, 09:11 PM
Make sure you are using turbulence on the emitter, not the fluid. (on the fluid you can use temperature turbulence, but avoid the general turbulence) The emitter turbulence could be as high as 5 or so, perhaps with lower emission rate or higher temperature dissipation.

The typical thing would be a lot of temperature turbulence, with high temperature dissipation. The amount of that and of the temperature buoyancy are really dependant on the scale of the flames and how fast or slow they should move( big flames will be slower). For fast moving flames you might need to increase substeps to handle the speed.

Also make sure the fluid resolution is high enough. 100x100x100 is pretty minimal for this sort of thing.

Duncan

Ubermatik
03-01-2011, 10:34 PM
Thank-you all so much! All your suggestions have been very helpful, and after etxnding the resolution drastically and altering the fluid turbulence, dissipation fuel and emitter turbulence levels, I've more or less got the effect I was looking for. I'm sure a bit more tweaking will gain the best result, as it might need to come to more of a point.

Thanks for your hep, as not only has it helped me with my project,but also extended my knowledge of Fluid FX for future use. Below is a close-up on the fireball!

Thanks!

http://img848.imageshack.us/img848/7820/firefinal.jpg

mandark1011
03-01-2011, 10:50 PM
that looks better for sure now adjust your opacity ramp under shading..look at the visor examples of flames to give you an idea of how this ramp should look.

good luck

Duncan
03-01-2011, 11:14 PM
It looks like it could still benefit from lowering the temperature emission(the brightness is a bit blown out against a white background.. always a problem with flames) then compensating by increasing temperature buoyancy and turbulence. Also sometimes increasing opacity helps with flames on a light background( simulates smoke mixed with the flames... the color attribute should be black)

Duncan

Ubermatik
03-02-2011, 06:26 PM
Thank-you for your extra help Duncan and mandark1011! It's helped me to tweek it just how I want it. Thanks for your solution and clear explanations too, it's been a great help! :)

mandark1011
03-02-2011, 06:32 PM
your welcome post a pic?

Ubermatik
03-06-2011, 08:43 PM
Sure! I know I've forgotten to turn 'display in reflection/refractions' on, but I'll change that in my final render :)

http://img135.imageshack.us/img135/7820/firefinal.jpg

Hope you like it! I'm pleased, though I'll probably turn the opacity down a tad too, so it's a little less bright.

Thanks again for all your help!

ginodauri
03-06-2011, 09:36 PM
I think you need more definition in those flames.
Try upping resolution , breaking opacity(this can really help for definition) , breaking colors little also.

http://img546.imageshack.us/img546/1649/flamesc.jpg (http://img546.imageshack.us/i/flamesc.jpg/)

Ubermatik
03-07-2011, 07:47 AM
I think you need more definition in those flames.
Try upping resolution , breaking opacity(this can really help for definition) , breaking colors little also.

What do you mean by 'breaking'? Alternating values?

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