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mabaza
06-19-2005, 09:12 PM
The LW documentation claims its possible, but I haven't been able to create anything remotely believable. I'm trying for a photo-realistic still render of burning cigarette ash. Any tips on how this might be accomplished would be much appreciated :)

MonroePoteet
06-20-2005, 10:20 PM
When I think of "burning cigarette ash", I think of a cigarette sitting in an ashtray, sending up tendrils of smoke. I'm not sure, but I think particle-based hypervoxels will have trouble doing long, continuous tendrils of smoke.

Maybe a really elongated, high-contrast, inverted fractal noise or FBM mapped to an undulating, tapered box would be better. Get those streamers of smoke rising slowly, undulating in the air currents.

The smoke in this image was created by having a flat, tapered box for the "smoke", setting it's transparency to 100%, then having an FBM texture elongated along the Y axis (60:1 vertically), 6 frequencies (to get the twistings), a texture value of -10, a very high contrast, and then inverting the layer. I also used the technique from the "electricy" video tutorial to have the smoke object undulate slowly, and rotated it back and forth slowly. The inverted transparency texture moves up the Y axis slowly. The animation looks pretty good to me, but this is just a still...

If you *really* want photorealism, you could always take a picture, of course. :)

mTp

mabaza
06-21-2005, 05:09 AM
MonroePoteet,

:eek: That smoke looks fantastic! I'm gonna try this technique right away. Do you mind sharing how you created the ash on the tip of the cigarette?

Many thanks!

starbase1
06-21-2005, 08:02 AM
I think you COULD do it with HV's, but you would need a lot of points very close together, probably several particle emitters, with some nice gentle swirly wind applied.

But that would be overkill for a still image...

Nick

jeremyhardin
06-21-2005, 09:24 AM
i don't think he's talking about the smoke. i think he's talking about the actual ashes coming off the cigarette. i could be wrong though.

agree about the smoke and using objects instead of hv's. here's a similiar thread along those lines...
http://vbulletin.newtek.com/showthread.php?t=35898

MonroePoteet
06-21-2005, 10:13 AM
Sorry, I misunderstood. Here are details on the ash:

The geometry was modeled into the Z axis:

1) Quite a number of segments, I don't remember how many I used. Probably 20.
2) "Accordian" the disc...i.e. every other segment's points are shrunk inward
3) Jitter it in X,Y,Z. Give it some randomness. Drag any rogue points produced by the jitter back into the mass
4) Quick triple-fan traversal on the end to make triangles for patching
5) Convert to patches (only the ashes)
6) Pull the ashes back into the cigarette tube a little
7) Paint a "glowing embers" weightmap using Airbrush at the base of the ash

The surface:

1) Grey color overall
2) The glow color is four layers:
2.a) Alpha gradient on the weight map (to occlude/pass red grid)
2.b) Red Grid Procedural to get pure red
2.c) Another Alpha gradient on the weight map (to occlude/pass orange turbulence)
2.d) Bright orange turbulence, moving in Y direction slowly
3) Luminosity is two layers:
3.a) Alpha gradient on the weight map (to occlude/pass luminosity turbulence)
3.b) Turbulence moving slowly along Y direction
4) Diffuse is Veins texture, shrunk 10:1 along Z-axis
5) Bump is Veins texture, shrunk 10:1 along Z-axis

The tip of the cigarette paper is browned using the same 2-layer coloring technique: a foreground alpha gradient based upon a weight map, and a background brown grid procedural.

Here's a closeup.

mTp

mabaza
06-21-2005, 10:16 AM
:D Jeremy,

You are right in that I would also like to know how to texture the ash and the glow of the heat. Any tips in that regard would be appreciated. In the meantime, I'm playing with the scene file you made in this (http://vbulletin.newtek.com/showthread.php?t=35898) thread and the technique described by monroe.

Thanks guys!

art_DA
07-20-2005, 09:31 AM
Mr. Poteet,

Absolutely love the cigarette you made and am trying this myself as I have a similiar project going on now.
A couple of questions.....

I am not getting the thin wisps of smoke with the flattened box and the FBM texture. All I get are dots. I have elongated the FBM texture at 60 m in the y axis in "scale" while the x and z axis are at 1 m.

Would it be possible to use an elongated and wavy tube that I rail extruded in Modeler and then use Spline Control to actually "wave " it in Layout?

Hope someone can help me.
Thanks in advance,
Art

MonroePoteet
07-20-2005, 04:21 PM
My guess would be that your texture is not correctly sized to your object. For example, my Smoke object is about 300mm tall (it goes way off the top of the screen in the posted image) and very narrow, and the texture size (X,Y,Z) is 5mm x 300mm x 5mm. 1m x 60m x 1m would only be useful for a really big object. You'll definitely need to play with the texture to match your specific object.

BTW, my Smoke object elongated box is only two inner sides of the box, flattened a bit, with about 50 segments along the vertical axis and tapered to emerge from the glowing embers on the cigarette. When the moving turbulence displacement map is added, it seems to writhe slowly, much like smoke.

Regarding the "dots", those may be the splotches in the FBM noise texture. Did you invert the layer? Inverting the layer causes the "webbing" between the splotches to be the texture rather than the splotches themselves.

I think you can use any object you want for the smoke, as long as its geometry approximates where you want the smoke to be constrained. The moving turbulence texture (with an envelope on the Y axis) for a displacement map is nice for me, since it automatically seems to have a life of its own with some natural variation. Using the Spline, you'll have to manually get the natural smoke curling animation.

Good luck!

mTp

art_DA
07-20-2005, 06:08 PM
You had mentioned something about an "electricity tutorial" on a DVD.
I don't have that DVD and was wondering how you actually made the box wave. That's why I had wanted to do Spline Control.
I don't mind moving the spline manually, but if there's a natural movement in the FBM texture, then I would prefer doing that.
I did actually manage to size the smoke object correctly. You are right. My cigarette and smoke object are huge, but I'll just make my smoke object texture huge too.
When I animated the smoke, it moved up the y axis like I wanted it to, but waaaay too fast. Your expertise in LW is far beyond mine, so I'll hope for the best here.
Thanks for answering,
Art

MonroePoteet
07-20-2005, 10:46 PM
Here's a link to the electricity video tutorial on the Newtek site:

ftp://ftp.newtek.com/pub/LightWave/Tutorials/Vidz/electric_CD.mov

and the main page for the video tutorials in general:

http://www.newtek.com/products/lightwave/tutorials/videos/index.html

Basically, it uses a Turbulence texture that moves over time, which is used as a Displacement Map for another object. The electricity tutorial uses a Null as a controller to get more randomized movement on the electric bolt, but I just made a Y-axis linear envelope for a more sedate twisting and turning of the smoke object as the inverted transparency texture slides across it.

mTp

art_DA
07-21-2005, 07:28 PM
So, what you're saying is that you didn't use the null controller at all and just made the turbulence texture rotate back and forth in the X direction in your Y axis displacement map of the already texture mapped smoke object, right?

Cool....

When I put a displacement map on my smoke object, it looked like nothing even affected it at all. Could it be that my object is huge and when I accepted the default displacement texture settings, they weren't big enough?

MonroePoteet
07-21-2005, 07:40 PM
You definitely need to scale your textures to match your object size. For example, if the default size of the Turbulence texture is 1m,1m,1m, and your smoke object is huge (say 60m tall), then the displacement will range from 0 meters to 1 meter, making it almost undetectable.

BTW, I'd recommend that you start modeling things to approximately real size. Then, the sizing on textures, etc., actually makes sense. You might even start with this project, bite the bullet and rescale all the objects to be about the right size. You'll have to go through all your textures, etc. to make them conform, but in the end, it all hooks up pretty nicely. As well, it makes combining objects from your home-grown library into very cool scenes MUCH MUCH easier.

All I did on the Turbulence is have it move slowly up the Y axis. It's a 3D texture, so it's displacing the points in all three dimensions. As it moves up the Y axis, the X,Z displacements change over time, giving a nice undulation. I then created keyframes for the smoke object to keep its base in touch with the ash on the end of the cigarette, allowing the undulations to go where they will.

That system is busy (render render render), but when it comes free (and if I remember), I'll package up the objects and scene file and post a ZIP.

mTp

art_DA
07-21-2005, 07:57 PM
Yeah...in the future I will do the real world size thing, but this thing has to be ready tomorrow and it's late.
Too bad I gripped a shoot all day today.
I tried bumping up the displacemnent texture BIGTIME and still didn't see the smoke object do anything.
I have a nice column of smoke going straight up with no other action.
It looks cool, but I need to make it "curvy".
Looks like I will be doing that in my compositing program.
Listen...THANKS for your expertise and advice and next time, which is who knows when, I'll be a bit more knowledgeable.

Art

MonroePoteet
07-21-2005, 08:54 PM
Here's the ZIP file with the objects and scene file.

mTp

art_DA
07-22-2005, 10:59 AM
Wow! Thank you Monroe!
I see what you mean.
Very much appreciated!
Now, I have to make it explode.

Thanks buddy,
Art