krakatoa style rendering

[Guna]

I am trying to create a nebula fx,some thing like this

Does anyone know how to render houdini particles like krakatoa does?

Tried a glow shader but doesnt work for me.

Thanks in advance!

[dobin]

constant shader with some transparency,

dive inside the shader and kill the node that multiply the color by opacity.

[jamesr]

A lot of the look comes from the sheer amount of tiny particles. Krakatoa uses a concept they call partitioning to render particles over and over again with slightly different positions. You can do the same in houdini with wedging by randomly varying a seed value in your particle sim for each time the wedge is run. This lets you design one sim, then run a bunch of wedges (like partitions in krakatoa) instead of directly simulating potentially millions and millions of particles all in one go. If you want more detail, simply add more wedges! You can then load all the wedges at rendertime and get a very similar result.

A couple of things that can help push the look are both tweaking the Alpha attribute of your particles, and adding a volume around it to help fill in the space.

 

Edited November 30, 2017 by jamesr

[Guna]

Thanks dobin and jamesr for your ideas,will try implementing the same.

[Jason]

11 hours ago, jamesr said:

A lot of the look comes from the sheer amount of tiny particles. Krakatoa uses a concept they call partitioning to render particles over and over again with slightly different positions. You can do the same in houdini with wedging by randomly varying a seed value in your particle sim for each time the wedge is run. This lets you design one sim, then run a bunch of wedges (like partitions in krakatoa) instead of directly simulating potentially millions and millions of particles all in one go. If you want more detail, simply add more wedges! You can then load all the wedges at rendertime and get a very similar result.

A couple of things that can help push the look are both tweaking the Alpha attribute of your particles, and adding a volume around it to help fill in the space.

 

Or get to know the Point Replicate SOP!

[toadstorm]

mantra's not the best at rendering lots and lots of points; it has a much better time with volumes.

you may want to consider using a cvex volume procedural to load all of your tiny points and create density at rendertime in your shader, using a point cloud lookup. if you want very fine detail, you'll still need a ton of particles, so look into point replicate or maybe use a gap filling algorithm to create new points where they're needed. then decrease your shader's point cloud search radius to as small as you can go before you start losing desired density.