I'm wondering if there's a better way to make a good smoke trail?

Right now I've got a cloud object as a child to a particle emitter. I figure it won't be done with the render until after the weekend. And from what I do see, I'm not sure if it's rendering the way I'd like. (So I'd have to postwork on it anyways.)

I'd really like to use an experimental falloff shader I got from SparrowHawke3D, but it has a bug or two and causes reflections or areas of complex light interactions to black out. If it wasn't for that, I think it'd be ideal and a lot faster than the clouds...

Only other thing I could think of is to paint a grayscale image of a "poof" and use that to control alpha on a particle's shader. But I suspect it'd look too repetitive.

Basically I need something to get the particles fuzzy/cloudlike, but not take forever like the clouds nor distinctively particles/spheres that look like the default emitter settings.

Did you ever get a copy of the free Flaming Pear "Cumulus" plug-in that AgentSmith hosted for a while? You could make some dandy "poof" sprites with alphas using that.

Attached Link: Smoke trail example

 Here's one I did with the particle generator (spheres) some time back. Animating the alpha with the Particle Shader function will provide you with a wide range of visibility options.

Sprites do a great job but aren't required. If you do use Sprites, increase the transparency value to something like 50 by typing directly into the value field instead of using the slider.

I never saw this plugin... we still can find it for download?

 It was a limited edition version created by Flaming Pear for Photoshop and distributed through Photoshop magazine or something like that. Agent Smith had permission to distribute it for awhile. My understanding is that it was quite slow but did make some nice results.

To get the same results, it's quite fast to render a white Carrara cloud against a black background and use the image as an alpha mask.

Ended up doing the effect in postwork this time, just takes too long with the computer I have to tweak the thing just right in render. I did play with a multiply mixer using turbulence noise and a "poof" map in the alpha that seemed neat (had more texture and less repetitiveness), but getting the particle size just right would have required a few trys, each of which would have taken at least overnight. :glare:

Also it was tricky getting it whitish enough and transparent enough without having it turn bright all of a sudden. (Is that a 5.1 bug, or does the newest one do that too?) Basically trying to get the kind of smoke that planes make when doing aerobatics at an airshow.

Would still like to figure out how to get it just right. Think it would be worth doing some test renders and posting pics+settings?

I'd be interested in seeing some test renders and your shader settings. I learn something new every time I read such posts. :-)

Ok, first setting up a test scene in case anyone else wants to try this in parallel. Some basic primitives with half of the particle emitter stream intersecting them. Might give an idea of how transparancy is interacting, etc.

And the initial particle settings for the generic scene above. Should also provide a reference point. Couldn't hurt if we work with some method to this madness. (I remember posts/threads doing breakdowns like this back in my earlier Brycing days. Dunno if there's much like that in archives on the Carrara side. Anyhow, couldn't hurt to see how various things behave and how strongly, etc.)

First comparison run. Setting the particle size to 0.5, then applying the blur effect modifier to different amounts. Seems ok for making particles smoky, but notice the shadows are still obvious, and that the blur sometimes distorts objects behind the particles. High blurs can also reveal the particle polygons inside. Shader in this case is the default gray, and particles are on diamond shape setting.

Very interesting experiment. Thanks for posting your screenshots.

Second comparison run, this time going through particle shapes. Again with default shader and particle size at 0.5. Showing how it looks with no blur, and 33% blur modifier. Seems that diamond, facing camera, and sphere shapes may have the most potential for making smoke. Metaball doesn't look too bad either. Child object was left out for this one. (Yes, clouds as a child object can make a smoke trail. But you need considerable CPU or time to throw at it. Otherwise it just takes too long.)

Particles set to facing camera and with 33% blur applied. Trying different sizes with default shader applied. Seems that the particle size to go with depends on how the scene itself is scaled. So this will be something that will need to be adjusted from scene to scene.

Another thing to note, sometimes the particle size changes don't seem to register unless you change some other variables in the particle emitter settings. I find that switching one of the toggle settings back and forth works for this. (Not sure if this is only a 5.1 bug, or something that actually carrys on into the latest version.)

 For smoke, I usually stick with sprites, otherwise the incongruity of the particle shadow to the blurred smoke is a deal breaker if the smoke is near an object. This method also gives you the ability to make "cartoon" smoke or get very realistic. 

Mark

A tutorial on your sprite smoke method including showing how to change the color as it progresses would be very cool.

Thanks for the illustrations and information from your "particle experiments" Paul.  Even if you didn't get exactly the effect you were shooting for, I'll bet you learned something useful in the process of all that work, lol.

*Mark B.- I also would love to see a particle sprites tutorial, either here, or as part of your VTC Carrara tutorial series. We're not trying to squeeze you to death here.;-0

 Actually I do have something like this already in my C6 tutorials.   ;-)

It's a little more sophisticated than what I've done for this post but it uses the same methods. I'll put something together and get it up though.

Did you tried to use a volumetric object like Fog or fire as a particles?? I did a simple test and it looks very cool. Its not the fast render solution but I think that its the better to control.

get the scene here:

http://www.4shared.com/dir/8187352/d836ef09/Scenes.html

Thanks Mark.