REAL fire is a light source.

is there some way to use the pyrofx as a light source?

In the “dancing balls” video from side effects, the fire is illuminating the scene. I really don´t know how to do it neither, might be something with the shader I think, or maybe using scattering.

There is some discussion of this in Mario's section of the Pyro Masterclass.

http://www.sidefx.com/index.php?option=com_content&task=view&id=1496&Itemid=132 [sidefx.com]

I think there were a few suggestions offered
Less expensive to more expensive.
-Use a few artistically placed point lights
-Instance point lights on to the pyro scatted points
-Fire volume is emissive/PBR solution.

okay, ‘village idiot’ LOL, perfect. so that leads to the next question.

if i am going to comp a pyro asset onto live footage, then the illumination needs to be kinda like a shadow pass.

i imagine that if i instance point lights to the pyro, then setup a lighting take that includes only the instanced pyro pointlights, then composite that pass with ‘lighten’ over the live footage, it would add the fire light to the live footage.

am i on the right track here?

no you are not.

In order to create interactive lighting on you plate, you need to construct the portions of it that you wish to illuminate in 3d.

Then illuminate them (using your instanced lights – or whatever other approach you choose to use). THEN comp that onto your plate.

Lights don't do anything if there is no surface (or volume) present.

G

Another idea is to take an isocontour of the heat field, apply a Constant shader, and use it as a emissive surface under PBR or under Full Irradiance in MP/RT rendering (using the VEX Global Illumination SHOP).

All the pyro videos use a fairly simple method for getting the environment to light up, discussed by Mario in his talk.

I used some scattered points inside the burn (or heat) field and instanced some point lights to them. If you want to you can relate the fire's density to the instanced light but in most cases I didn't even bother. It's better to render out a couple of passes.

But as you can imagine this will result in massive rendertimes, since the pointlights will influence your sim as well. Not necessary as this get's done by the pyro shader. To get around this problem you need to link the pointlight to only the correct geometry in the scene. This can not be done using the light linker. Seperate categories will have to be set up.

The weird thing is that by default every light has a categories field under the light tab but your object doesn't. You need to add this as a render property to your geo. Now you can fill in a category name for your light and use that same name for your geometry. If set up properly your fire will only light up the environment. If I can find the time I'll set up a quick scene to illustrate this.

Ow, it's also useful to use ramps and an expression (using the bb) to crop your area for scattering. So you have more control over where the lights should appear. Saves rendertime as well.

It's also a good idea to use the rendered pointcloud (simply load it using a file sop) as a source for instancing. This will carry all the necessary attributes to link to your lights.

would love to see a hip file with some of these steps as examples! and any of your promo hip files too would be so awesome