Flying Paper Lantern Material

Maybe I’m retarded, but I can not get a decent paper lantern material to look right. You know those paper things that you light and they float up into the sky. It’s just paper with a fire in the center bottom to cause it to rise like a hot air balloon. I’m going to need 1000’s of these so I’m not sure I should even use particles for real fire. I was thinking just a short video clip of fire set to the color of an emission shader. Most of them or all of them will be at a fair distance so that minor detail will not be visible. Any ideas?

I’ve tried SSS nodes, but they never look real to me. I’m going to make them fly over head maybe, or I’d just use a sprite. I’d prefer a real 3d model with actual fire lighting it, but that may not be possible.


Before you do anything further you should try to set up a test scene with thousands of tiny light sources in Cycles. I have a feeling that experience might be so utterly disappointing that you don’t have to worry about the fire/lamp shade materials any more.

As pointed out by IkariShinji, this kind of scene is a nightmare for cycles. Cycles doesn’t work very well with too many light sources… but there are some workarounds to get a nice render.

the paper, should be an emission material and not a sss/translucent/diffuse. you should need to render all the lamps in a separate pass, with bounces set to 0, and render the rest with just a few area lights just to simulate the radiosity the lamps throw to the scene.

for the paper/emission, you can bake a few lamps alone, and then use the bake to color the emission.

LOL, you are probably right, but I’ll find a way around the limitations of my system. They don’t have to actually be lights. There are many ways to go about this. I was just wondering if anyone had an idea I hadn’t considered.

Very good idea. I’m a bit fuzzy on passes. I’ve never used them. I know what they are, but I don’t know how to recombine each pass into a final image. If that is even how you do it. I need to learn this because I’m way past intermediate and the things I want to make are massive and complex. Would make it a lot easier to break up scenes with millions of faces into easier to render chunks.

The problem is not the millions of faces, but the number of small light sources. Cycles is a lot more happy with a single large light source then four small ones. Ace had a thread somewhere about this a good while back, but I couldn’t find it.

If you want the lights to be actual light sources, and try to render something like the photo, I’m afraid you’re out of luck with Cycles.
If you can fake it, here is how I would think about the problem, although I can’t really experiment with it myself: Procedural masking based on vectors (surface angle -> camera pos and so on) to calculate a gradient emitter which is only seen by the camera (actual lighting of the scene would be something much simpler):

  1. Inner surface where visible is brighter then the outside of the surface.
  2. Brighter at the bottom of the hat due to light source being closer to the bottom.
  3. A “specular hotspot” even on the outside causing a circular shape.

The two first ones should be easy enough, just mask with surface facing and object y coordinate.
The last one would involve obtaining position of object, offsetting in object y space, and a radial gradient scaled depending on distance to object. Should be shifted along object y depending on object x and z rotation (starting to make it too messy for me). Sounds like some vector maths and space transformations are required, but maybe somebody else here could give it a try?

When the desired mask is obtained, just add it to an emission material that is only visible to the eye. Diffuse or glossy reflections of them would also have to be faked, possibly impossible to make it look “right”, so making sure it’s not focus of viewers attention and you may get away with it.


3000 particles for the lanterns

Best of luck