Pyro diagnostics

[plazadelmar]

I'm curious how to use diagnostics to find errors in the sims. I have a pyro sim and when I'm running diagnostics it tells me the grids failed the test. Yet everything is working like expected. Is it something to take seriously or not? Any advice about this would be appreciated. Thanks

 

 

[Atom]

Think of it as a clip or peak in an audio signal. Sure you can turn up the volume, but at some point you'll exceed the head room and produce a distorted signal.
The same is true with density. Once you exceed the valid range, the value will be clipped and your are losing precision at that point. The most common artifact will be blockiness while rendering.

It's not a show stopper. If it looks good, it is good.

You may only see the artifacts when you attempt to use the exported VDB in another package. Other packages may attempt to auto-correct the bad values. By keeping them in range to begin with, you can avoid that.

Edited June 20, 2020 by Atom

[plazadelmar]

46 minutes ago, Atom said:

Think of it as a clip or peak in an audio signal. Sure you can turn up the volume, but at some point you'll exceed the head room and produce a distorted signal.
The same is true with density. Once you exceed the valid range, the value will be clipped and your are losing precision at that point. The most common artifact will be blockiness while rendering.

It's not a show stopper. If it looks good, it is good.

You may only see the artifacts when you attempt to use the exported VDB in another package. Other packages may attempt to auto-correct the bad values. By keeping them in range to begin with, you can avoid that.

I've been trying to normalize the volumes where possible and on import I created vop node with normalized Cd. Is there some other way I could normalize the volumes to stay within the range? Also, how can I read out values to see where my volumes are out of range? I'm learning this and all input is appreciated.

[Atom]

I generally assumed that density should remain in the range of 0-1, but you can overdrive it. This produces that minecraft blockiness that you see in a lot of new user renders. I wouldn't worry about it too much. Just as with audio, if you normalize too much, you can flatten out your small details.

With the VDB Diagnostics node I typically activate Uniform Background. This can help knock out some background noise for density values near zero, but not zero. Under General Test you can fix values in range, but I don't think that remaps them. The help card is a little lean on this node.

Input is the best place to start for controlling your values. Try not to overdrive it from the start. This simple setup can allow you to play around with values by adjusting the @density value inside a Volume Wrangle.

 

Edited June 20, 2020 by Atom

[plazadelmar]

3 hours ago, Atom said:

I generally assumed that density should remain in the range of 0-1, but you can overdrive it. This produces that minecraft blockiness that you see in a lot of new user renders. I wouldn't worry about it too much. Just as with audio, if you normalize too much, you can flatten out your small details.

With the VDB Diagnostics node I typically activate Uniform Background. This can help knock out some background noise for density values near zero, but not zero. Under General Test you can fix values in range, but I don't think that remaps them. The help card is a little lean on this node.

Input is the best place to start for controlling your values. Try not to overdrive it from the start. This simple setup can allow you to play around with values by adjusting the @density value inside a Volume Wrangle.

 

Thank you so much for sharing your knowledge.