Hi,

I watched a lot of tutorials, read a lot of forums however can't seem to get the awesome look of the explosions around the internet.

I decreased sample size to 0.04, tried ray tracing and micropolygon rendering. Played a lot with Stochastic Samples and Volume Shadow Quality. Played with density of smoke and fire, in addition added materials and played with them. I always end up with low resolution smoke with big pixels in MPlay. So far I can't get the explosion I created in FumeFX months ago.

I also saw in forums that people talk about Volume Step Size parameter in render settings however in Houdini 15, I can't seem to find it. Also read that in Houdini Help Section, it is suggested that pyro volume’s container resolution might be low. How do I change it?

What should I do? All I want is a puffy explosion.

Help me please.

TazdingoMan
Hi,

I watched a lot of tutorials, read a lot of forums however can't seem to get the awesome look of the explosions around the internet.

I decreased sample size to 0.04, tried ray tracing and micropolygon rendering. Played a lot with Stochastic Samples and Volume Shadow Quality. Played with density of smoke and fire, in addition added materials and played with them. I always end up with low resolution smoke with big pixels in MPlay. So far I can't get the explosion I created in FumeFX months ago.

I also saw in forums that people talk about Volume Step Size parameter in render settings however in Houdini 15, I can't seem to find it. Also read that in Houdini Help Section, it is suggested that pyro volume’s container resolution might be low. How do I change it?

What should I do? All I want is a puffy explosion.

Help me please.

What you mean with “sample size”, sounds like a mix of division size and samples , taking its a float I guess its the division size.
That number doesnt really say that much out of context. Its the size of a voxel in world space. So 0.04 is “high” resolution if your camera is far away in a 1km scene, however in a small explosion up front it might not be enough.
I dont think that this is your problem though, have you lowered or changed the volume filter?
This is a parameter on the geo node you are rendering your explosion from. Look under the tab render/shading, you got a volume filter and a volume filter width. Default is box with width of 1.

Edit…
You got a .hip file to share?

Also this looks more like a problem of your Simulation, not the render of it.

Try increasing the resolution if the simulation, that should help.

Hi again,

By “sample size” I meant “division size”. Sorry I got confused in all these parameters and options

On the contrary, what you said about camera might be the solution. That is something I never thought/heard of actually. I am actually a Blender user and trying to learn Houdini for its magnificent VFX opportunities which Blender lacks. And camera options never created a problem there before.

Yes I decreased the Volume Filter to 0.1, it made my smoke better/realistic/FumeFX like, however, as baldwithglasses said, there seems to be a resolution problem. This may sound super dumb but only resolution option I see is in camera options and I set it to 1280x720. Is there any other option.

I attached the .hip file too.

Here is a render of your scene with following changes
1. Volume filter from gaussian 0.1 to gaussian 1
2. mantra pixel samples from 24*24 to 4*4
3. I also killed your pointlight1. Nothing will ever look good strongly frontlit.

This doesn´t look as the awsome stuff you see on internet, but hopefullt it will get you started.


The resolution baldwithglasses refers to is the division size. Lower this parameter to get more voxel = more detail = longer simulation times.


From the help about volume filter…

Some volume primitives (Geometry Volumes, Image3D) can use a filter during evaluation of volume channels. This specifies the filter. The default box filter is fast to evaluate and produces sharp renders for most smooth fluid simulations. If your voxel data contains aliasing (stairstepping along edges), you may need to use a larger filter width or smoother filter to produce acceptable results. For aliased volume data, gauss is a good filter with a filter width of 1.5.

Wow this really took care of the resolution problem. Sorry I forgot the pixel samples 24*24 while trying things… I thought volume filter must be very very very low like pixel samples but as you showed it is not.

I was actually worried about the camera. Did you check it?

About the light, you deleted the point light ok. What should I use for lights?

Thanks for your help. I'll post my results if things get better.

Looking forward to any other ideas.

Hi, I got the same problem, but in c4d with octane vdb. In my case the density was too high.

May be that can help.