openvdb

Hey KWD,
How are you? Your work is really appreciated.
Wish you all the best :slight_smile:

Hi,
Is it possible to find a Blender standalone of the current openvdb smoke simulation version ?
If it is, where can I find it please ?

My real goal is in fact :
to be able to render a smoke simulation (that I’ve baked from Maya fluid sim) with Blender Cycles.
Yet Maya’s fluid sim bake Export file format is openvdb. :confused:

There is no build currently available. Even if there were, what you want to achieve wouldn’t really be possible in the branch ; although you can open an external file (from Maya in your case) in the Cycles nodes, you will most certainly have scaling/orientation issues (as I don’t expect Blender and Maya to have the same unit system). (This will change in the future.)

Greta work on the OPenVDB implementation. I am a Blender Newbie having used XSI for ages, trying fluids smoke sim in Blender for the first time. I would like to render the vdb files in Redshift and Arnold, but the prefix numbering after the frame counter is in the way - I have to use a filerenaming tool to get rid of that. It would be convenient if you implemented an option to have prefix before the counter, and add a filename, in the format filename_####.vdb

Oh and a coordinate system switcher for y-up would be handy too.

Thanks
Morten

Hi everyone ! Recently I tried to bring blender vdb caches into guerilla, and it worked fine except there is no temperature channel in the blender vdb output. I guess that for blender the ‘temperature’ channel stands for ‘flame’. So I’ve managed to hack this by importing the blender vdb into houdini and change the channel name. And then reimport the changed vdb sequence back into guerilla and here is what i’ve got so far!





The result isn’t exactly what I wanted (the flames are a little bit weird looking in my opinion compared to the ones inside blender viewport render) but I think its because ‘temperature’ and ‘flame’ channels aren’t exactly the same.
If someone knows more about this…
Thanks

I there, I found this interesting thread on the Houdini Artists group on FB…
The guy will make a tuto in order to render fire and smoke from Houdini into blender.

KWD,
However ‎Alexander Weide‎ (the poster), says that according to him there is an issue with the OPEN VDB in blender.
I’m just posting that if it can helps the future development…

Seb

https://s24.postimg.org/uisho56gl/Capture.jpg

There is no issue here, the implementation is meant for Blender specific smoke caching, it is not meant to be used in other software, or bring volumes in from other software, although both of these are possible. To be really cross application, Blender would need to handle volumes better ; for which I am proposing to have a volume object, but I don’t really have time to work on that. Here’s a months old video of my efforts in this area (for those who haven’t seen it yet):

Thank you for the explanation KWD !

I don’t mean to be critical and definitely appreciate implementing it into Blender, but find this rather frustrating as someone who writes software that uses openvdb. What is the point of adopting an open standard library if only to use it in a non-standard way. As they are the vdb files Blender generates are rather limited to use with anything other than blender, as well as bringing in Houdini vdb’s.

There were (are?) plans to fully implement OpenVDB input/output in a standard way into Blender. The OpenVDB cache was originally viewed as a sort of pilot program to start doing something useful with the code right away, and as far as I know KWD simply ran out of time to fully implement everything that was planned in terms of the format. Blender itself ended up having some shortcomings (notably, the absence of a volume object type) that got in the way of a smooth OpenVDB workflow, and until those problems are solved it is seemingly on the back burner. Personally, I would love to see it take a higher priority as well. Blender’s track record of keeping up with upcoming standards and fully implementing long-standing ones is shaky, to say the least.

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Ah ok. Well appreciate getting it in there at all. IMO one way could be to do it similarly as the dupli group setting on Empties, just do it as a OpenVDB instead of a dupli group. That’s somewhat how we do it in the RenderMan Addon (just don’t get to visualize the vdb).

Anyway I’d be more than willing to help implement Openvdb completely.

Just so people know, Alexander wrote on that FB post that his Houdini asset to export Blender VDBs from H is going to be released on BlenderMarkets along with the shaders to get pyro volumes working properly.

I’m pretty excited about this!

Now… if someone could write a Cycles ROP …

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And here is the preview by Alexander :slight_smile:

https://vimeo.com/196476305

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it’s online ! :slight_smile:

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sweet! once I’m done hiding from the christmas crazyness downstairs I’ll grab my wallet and check it out.

Could a VDB exporter from Blender be possible in 2.8?

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You can already “export” vdb files when you bake simulation in 2.79. However the blender vdb implementation uses it in a completely non-standard way. Hence the special exporter that you have to pay 15$ to get Houdini vdbs into Blender, and Blender VDB’s can be used basically no where else.

The correct solution to both of these problems is to implement VDB’s the same way everyone else does.

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Uh…got a link to where I can pay $15 to get Houdini VDBs into Blender? Google is coming up empty and i’d definitely pay $15 for an addon if it worked reliably.

look a few posts above

https://www.blendermarket.com/products/houdini-2-blender-cycles-pyro-exporter

:-1: can’t no longer link to a post?

You can use Blender’s VDB cache files directly in Octane.

Jason