Hey all,
here’s a tutorial on the technique I used to create the clouds in my Stealth animation. Hope you can use it! 
Right-click here to download the tutorial(10 mb PDF)
Right-click here to download the sample animation (2 mb Quicktime)
Cheers,
You mention in the last paragraph how things will begin to show when animating…how did you manage get around that?
Thanks
Don
Hi, thank you for the question.
I didn’t get around that, and you can see the intersection artifacts in the second clip in the MOV:
http://www.duck.dk/tutorials/jussing_cloud_tutorial.mov
These artifacts only show when using the highlight technique in chapter 4.
You also have intersections with the regular particles (the first clip in the MOV), but those intersections are invisible because of the uniform colors.
The intersections start showing, the moment you create particles with different colors or texture maps.
This looks very interesting! I haven’t had a chance to try it myself yet (have just read the PDF) and it strikes me that you might be able to avoid some of those edge artifacts by using the cutout function in the A&D shader? That might remove the transparent parts from being hit at any rate, perhaps - admittedly as the clouds face the camera there would still be brightness issues on the cloud areas…
I have been trying experiments at faking volumetric clouds myself using spheres with normal mapped gradients and displacement - these create very good fractal cloud edges at certain angles, but are hampered by a similar problem - as soon as you rotate the camera the cloud changes form. I have used this as a technique to render out nice flat cloud cards for placement in the distance in a scene, but it’s certainly not what i was hoping for.
Thanks for reading the tut.
What’s the A&D shader? Do you mean Mental Ray’s Architecture and Design? If so, then no, there’s no “cutout function” or special render features here, it’s just an opacity map in a totally standard 3ds Max material, it’s meant to be rendered with Max’s built-in scanline renderer (though it renders faster with MR).
I understand your approach with spheres, I’ve tried that myself, but so far, billboards with gradients and ambient lights is the best approach I’ve tried.
If angle is your big problem, then you should definitely try this tutorial - as the animation shows, you can render the cloud from any angle, and even fly through it.
Cheers,
really like it! nice approach and something close to what pixomondo images did for “Red Baron”…
Nice Jonas:) Afterburn Clouds are great but the render overhead just kills the practicallity of it (from the earlier thread )
This approach seems to be quite a bit more controllable/less resource intensive.
@Anselm, that cloud generator Pixomondo’s got looks epic man:D
@moidphotos: It strikes me now that I misunderstood your last post - you’re suggesting a way to avoid the artifacts. But I still don’t think the cutout function is going to work. The artifacts are an inevitable consequence of differently textures billboards intersecting each other.
@psycho: Thanks for the comparison, Pixomondo’s work on Red Baron is absolutely awesome, beats the crap out of “Flyboys”, and I also like the clouds better than in Stealth (which was also awesome)
@Johnny: Thanks.
Cheers all,
Brilliant tutorial! Really very easy to follow and the principles that it covers can be used in soooo many ways!
Note to others: don’t limit yourselves to just creating clouds after reading this tutorial!
Jon
This a great method (Thanks for that!).
But I wish there were a way to apply it to multiple clouds rather than a single cloud structure. Currently, in the fluffy teapot and tunnel examples, a single light lights a single cloud structure. I want to light multiple clouds which are each separated from each other by a distance (picture individual clouds in a blue sky). This would require an individual light for each cloud so that the clouds would each have a light and a dark side.
The only way I can imagine this could be done with this lighting technique is if there was a script that generated each cloud and it’s light, set the light to only include that cloud, and then had some means where when you changed one light’s position… all the cloud lights position changed so their direction would always match. (Don’t know what this would do to rendertime compared to AB, etc.).
Thanks!
Hey Mike, that’s spot on true!
In the larger scenes I’ve made, that’s exactly what I’ve done - multiple lights, one (or more) for each cloud.
I’ve tried out a technique with mapping an inverted z-depth buffer out over the landscape, that kind-of sort-of works with only two lights for the entire cloud landscape, but you’re propably better of getting a real volumetric render.
Thanks for the continuing support, it means a lot.
BTW, if any of you guys have tested the tutorial, I’m dying to see your results. Please post.
I found some videos on YouTube from people who did the tutorial:
http://youtube.com/watch?v=fNGBBL6wOmY
http://youtube.com/watch?v=4VvWFQq6igU
http://youtube.com/watch?v=ndNgvdj2GIA
http://youtube.com/watch?v=IGx529cx-1M
http://youtube.com/watch?v=1b4d7zNok0Q
http://youtube.com/watch?v=TWLJ-1yGPsk
http://youtube.com/watch?v=bfaek0fVUQw
http://youtube.com/watch?v=KkcDvDQWLC0
if you know more, I’m dying to see them!
Jonas
