Best practices for particle self-illumination? (geo-light vs. light in

[borbs727]

The title seems to have been cut off. It should read: Best practices for particle self-illumintaion? (geo-light vs. light instancing vs. point cloud driven lighting)

 

Hey everyone, 

 

This explanation rambles on a little bit, so I'll sum up my questions at the end of the post and provide a simplified HIP that I'm working on: I'm about 1-2 months into Houdini and now I'm playing around with particles and trying to get some custom firework effects to work.  I want to try and keep things procedural, so I'm using the DT cloudscapes tutorial to create the fireworks explosion smoke (particles with vdb).  They're a bit stiff and steppy, so if anyone has suggestions on how I could improve the effect (or a better alternative) that would be great!  I've also used a HIP I found to create custom explosion shapes based on goal geometry.  Everything was working great until it came to the lighting tests.  I want use the fireworks to illuminate the smoke clouds (reference:

)  but I'm not sure how to go about creating self-illuminating particles that can light up the explosion smoke. My first instinct was to use the glow shader, but this didn't work at all, so I then tried the geometry light.  This was ok, but I could only get the geo light to work on the out-of-the box fireworks.  For some reason my custom fireworks won't take the geometry light... any thoughts?  I've done some research and read about particle instancing lights (which might be the way to go because I can instance point lights) as well as using a point cloud to drive illumination.  The point cloud option sounds really cool, so if anyone knows how i'd go about pulling this off I'd like to try it (the forum post that talked about this technique didn't explain how to do it, they just suggested doing it).

 

Summary:

1a. My procedural smoke clouds are a bit steppy, any suggestions on how to make them flow more smoothly

1b. Also, is there a way to get it so when the clouds are birthed and die they dont' just appear and disappear?  Like the volumes can grow and shrink?  I'm guessing using a birth/age attr will do the trick, but i'm not sure how to set this up correctly.

2. The geometry light is only working on the out-of-the box fireworks and not my custom firework network.

3. Can I use particle instancing to attach a light to each particle? I've read a few places that this can be unstable, so are there better options?

4. How can I use a point cloud on a particle to drive illumination (if this is a viable option)

 

Thank you!

fireworks_geoLight_odforum.hipnc

Edited May 18, 2015 by borbs727

[borbs727]

So after a couple of days, I'm starting to see some results and have answered a few of my questions:

 

1a + I went over the procedural volumes tutorial again and took at look at the hip file to see how well his clouds were animating.  The volumes in the tutorial are so immense that you can hardly notice them stepping along the edges (but they're still stepping)  I'm going to try increasing the number of particles to see if this helps get rid of the choppiness, but if it doesn't I'll try to figure out how to manipulate scale with age to see if that does anything.

 

2) I'm no longer trying the geometry lights out.  I've realized these types of lights make for awful volume renders.

 

3) I took another look at Peter Quint's light instancing video again (https://vimeo.com/8681435) and found in the comments that he updated the tutorial to work with later versions of Houdini using an ASAD light.  This works really well for illuminating volumes because ASAD is a point light by default.  To get the look I wanted I only really had to play around with the material node's color para (for intensity), the pyro shader's scattering phase (controls what direction the light penetrates in a volume), and the attenuation ramp on the ASAD light (for light spread).

 

4) Haven't been able to try out any point cloud driven illumination stuff yet, and I'm not sure where to being with it either, so any tips/tutorials would be much appreciated.

Edited May 20, 2015 by borbs727

[humourharsh]

Just a basic fireworks

fireworks_01.hip

[indu8max]

thank u harsh