Hey everyone,

So in this shot I want to have a laser blast the rock. I was wanting to have the laser light emit for a few frames inside the blast area that has already been sim'd. Do any of you have a good way to accomplish this? Originally what I tried was creating a sphere with mountain sop and have that emit light in the explosion area but I could never get the light bright enough to shine through the smoke and shine onto the rock. Any pro tips out there?

Side note: I am using octane but if I'm assuming any tips you have should translate over.

I don't know if this is something I need to do inside of pyro with a heat volume or if I can fake it with a light being emitted by a secondary object since it only lasts like a frame or two!

Vincent Griffith

Have you considered doing this in post with Nuke or After Effects?

I was just concerned that I wasn't going to get the accurate light bouncing off the inside pieces of rock and shining through the insides of the volume. I just feel like it should be easier and look better to do this inside of Houdini.

Still having trouble with this. Does anyone have any other ideas they'd be willing to share?

Masking a few frames and making a light in Nuke, Sapphire, or AE is easier, but you can create a laser light effect in Houdini in a few ways that I can think of. All have some problems.

One is to create a line in Houdini with a poly wire, and have an emissive color.

Another other way is to create a spot light with a very small angle and raise the intensity very high. That will give you the light off the fragments properly, but the light itself will not display. You can fix this with adding a volume, but be aware that any other lights will now have to deal with this volume. In a real explosion, there is lots of dust/smoke and the laser would reflect off this, so you would have to create the equivalent in Houdini.

You can just scatter points on a line and adjust the scale.

Lastly, you could try to do this with a particle emitter and directional force without gravity. This will allow the light to change direction when hitting a fragment. You have the option to have collisions generate secondary particles, which might be useful if you want sparks coming up from laser collision with the fragments.

Attached is a file that shows these methods, if you really want to go that way for a couple of frames.

So what you are doing with the point light in the center of everything is pretty much what I want to do for a few frames. The actual laser isn't the problem really, it's more the blast of light from the center of the blast like the point light is doing. The problem is in octane I can't get it bright enough to actually do that with the volume present.

Hey so I ended up doing it in comp for now until I can find a better way in Houdini. Right now it doesn't feel right to me. I pretty much added a glow and a green color color cast to the smoke for a few frames… I really want to do it the “right” way but for some reason nothing is working for me. This also needs more micro rock pieces shooting around but that stuff I'll do later.

Watch Here [vimeo.com]

Password is “laser”.

I don't know how Octane works with volume lights, as I don't use it. Geometry and Volume lights are slightly different by default (whether point cloud is turned on and if the original geometry is hidden). You might try to see how this renders in Octane.

A lot of rendering engines use their own lights and materials. Is your issue a specifically octane volume light?