Fire texture

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ozzie
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Fire texture

Post by ozzie » Thu Nov 06, 2008 1:08 am

Does someone ever made a good looking fire texture in indigo (I don't know how to write shaders so its out of my league)

I found this:
http://www.indigorenderer.com/joomla/fo ... re+texture

but I still in *** hole.
My idea is:
model several flames, with different textures + transparency, add emiter inside and pray :)

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BBjam
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Post by BBjam » Sat Dec 27, 2008 9:37 am

as of 1.1.6 materials can emit light from their surface(not volume :( ), so you could make the flames light emitting diffuse-transmitters. I'm haven't used indigo in a while though, so it might not work.

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eulgrand
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Post by eulgrand » Mon Dec 29, 2008 8:28 am

Here's my try at diffuse emitter. If you find this solution acceptable, I can post 3 or 4 maps (diffuse & clip) that I arranged from http://www.kavewall.com/stock/index.html

The purpose was to see what amount of light could get out of the emitting diffuse map without appearing completely burnt (don't look for wood under the fire, there ain't). The answer is not a lot.

Would be nice if back faces could emit too (works with KT...).

Hope this helps :wink:
Attachments
im1230469472.jpg
SketchUp scene. Both fireplace, candles & painting downloaded from 3DWarehouse.
Camera tonemapping. Apperture diffraction ON. A little bit of post-pro (vignetting)
im1230469472.jpg (170.66 KiB) Viewed 6566 times

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Kram1032
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Post by Kram1032 » Mon Dec 29, 2008 11:20 am

for backfaces... could you slightly extrude the planes? via planar projection, you could get bisided textures. If the thing is thin enough, noone would notice the edge. :)

That render looks promising to me :)

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eulgrand
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Post by eulgrand » Mon Dec 29, 2008 8:45 pm

Kram1032 wrote:for backfaces... could you slightly extrude the planes? via planar projection, you could get bisided textures. If the thing is thin enough, noone would notice the edge. :)
Actually I didn't extrude, I copied/rotated and translated ~2mm backwards. I'll give a try to your solution, but I'll have to have an inverted clip map, otherwise we'll see pieces of black (back) faces behind (unless the pasted UV mapping also applies to the clip map - I definitely have to try this !)
Kram1032 wrote:That render looks promising to me :)
Thanks a lot :wink:

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Kram1032
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Post by Kram1032 » Tue Dec 30, 2008 12:08 am

of course, that also works :)
though, no idea if it's still the case, but there *was* a bug with diftrans, that the last pixel row showed solid, no matter what you did. - One solution was, to make it a not ending surface - the simplest way to do that, is to make it solid :) (eg adding a volume)

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eulgrand
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Post by eulgrand » Tue Dec 30, 2008 5:14 am

Kram, your solution seems to be working, even if actually the flame diffuse emitter is almost emitting nothing (otherwise the diffuse image is completely burnt). The orange light is cast by two orange panels hidden in the fireplace !

The burning wood is to be set.
Attachments
im1230559014.jpg
Light sources are the flame, the candles, two panels hidden in the fireplace and one panel (2500K, ~0,25m²) on the right of the scene. No aperture diffraction
im1230559014.jpg (235.26 KiB) Viewed 6497 times

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Kram1032
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Post by Kram1032 » Tue Dec 30, 2008 10:39 am

did it emit more before?
how does it look like with aperture diffraction?

An other idea: blend that nice diffuse transmitter with a NULL via a luminosity version of that flame texture :)

And a suggestion: Fire is very orange, but I'm pretty sure, it's not THAT orange...
and I somehow miss that blue part in the candles' flames... though, that might be due to lack of zooming ^^

I think, the best possible candle flame (without taking into account 3D texturing, particles, etc.), would be a simple conal mesh with smooth tip and smooth bottom, and a simple (cylindric mapped) texture:
blue at the bottom; transparentish; orange; yellow; transparentish and white in the middle; orange again; smootly getting transparent toward the tip.

How far is ISL with view-dependendness? because the transparency part would work perfectly with view dependendness, rather than a simple gradient. :)

though, photos somehow lack the blue part in candle flames...
Image a rare shot, where you can see the blue part (not only in the gas flames)


unrelated but nice:
Image
Image

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CTZn
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Post by CTZn » Tue Dec 30, 2008 7:26 pm

Hi Eulgrand, not sure about the technique you used, but what your scene lacks the more imo is light dynamics (beside much less saturated fire texture I believe ;)). It's like if all the flame parts were emitting the same amount of light, while in reality hotter spots are also brighter (yellow flame as opposed to red).

So what I suggest is to make a range of different expositions for the fire texture, where the less exposed shots will be mapped ahead (yellow spots), and darker, red frames, behind. But again, maybe you did something alike already, I was just not sure how to precisely interpret your rig.

Fire is challenging, I can not imagine a definitive solution for it :)

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Kram1032
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Post by Kram1032 » Wed Dec 31, 2008 8:16 am

I think, the only solutions coming at least close to perfection, are particles, coloured via a 3D-gradient, or something like that. else, it's just impossible to get real real flames.
shots with "correct" brightness look overexposured
shots which show the colour, are too dark and oversaturated
what's needed would be a HDR-shot xD HDR is close to impossible, from something as dynamic as flames, if it's supposed to be sharp.

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Borgleader
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Post by Borgleader » Wed Dec 31, 2008 9:09 am

Particles can do a good job at it, but so far Blender particles seem to be out of the question :(

http://coyhot.free.fr/main_Container.html
Or we could have this :)

http://farsthary.wordpress.com/
Or this (further down)
benn hired a mercenary to kill my sig...

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Kram1032
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Post by Kram1032 » Wed Dec 31, 2008 11:00 am

yeah well... true volumetrics for blender is truely awesome.... but that doesn't mean at all that Indigo supports it, just because of that :( :P

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