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ManHatTan

Force Houdini to release files?

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Hi. I'm loading a lot of alembics and textures that I update in other programs. My problem is that I can't save the new versions with the same filename since Houdini locks the files. Like the title says, can I get Houdini to release loaded file without removing the node?

Edited by ManHatTan

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I believe this has more to do with the design of Alembic than Houdini. Don't quote me on this, however, Alembic turns into a memory like file state so that it can stream the data. This is one of the unique "features" of alembic compared to say FBX. This is how it allows the format to stream in the data so fast at runtime speeds. The workaround if you need access quickly and still want to keep performance, is to place a file cache node after it and write the alembic information to disk into Houdini's native file format, and then delete the alembic cache from Houdini. You can set this up in an HDA, with a call backscript, or in the hda's python module to press import alembic, press render file cache, and then press delete alembic file tree. If you need the hierarchy for say a DOPs sim it's best to make a copy of the Alembic file into something like a TEMP directory if you need simultaneous use of it.

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On 10/30/2020 at 6:07 PM, LaidlawFX said:

What texture format are you using?

 

I'm using alembic mostly because that seems to be the newer and better format, but coming from Modo/Max/Maya, I've always used FBX. I'm not animating anything, these are just static meshes, is alembic overkill in that case?

Textures are mostly TIF's.

 

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The best answer I can say as to Alembic vs FBX is to pick the right tool for the job. Outside of playing 20 questions to ask about nuances it's easy to go either way. You may want to keep FBX as it's commonly supported across all packages. There is no nice Alembic Object node, so you are stuck using the Windows menu. The File Sop and Alembic Sop do a lot of the same thing. I guess I would say it comes down to are you porting materials, and how big are the files? With materials, I would stick with FBX unless you got a little R&D time to pack the materials. Or with big pieces of geometry go alembic. 

I would scarily enough suggest trying USD if you are still at the point of deciding a new format. That will be the best long term. 

Your tifs should not be held in memory by Houdini. EXR can have that issue like Alembic. It's possible that a specific node may be holding the texture in memory. The scene would have to be debugged to figure out that one. They don't refresh in the viewport in Houdini unless you press the refresh option in the windows bar.

Edited by LaidlawFX
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19 hours ago, LaidlawFX said:

The best answer I can say as to Alembic vs FBX is to pick the right tool for the job. Outside of playing 20 questions to ask about nuances it's easy to go either way. You may want to keep FBX as it's commonly supported across all packages. There is no nice Alembic Object node, so you are stuck using the Windows menu. The File Sop and Alembic Sop do a lot of the same thing. I guess I would say it comes down to are you porting materials, and how big are the files? With materials, I would stick with FBX unless you got a little R&D time to pack the materials. Or with big pieces of geometry go alembic. 

I would scarily enough suggest trying USD if you are still at the point of deciding a new format. That will be the best long term. 

Your tifs should not be held in memory by Houdini. EXR can have that issue like Alembic. It's possible that a specific node may be holding the texture in memory. The scene would have to be debugged to figure out that one. They don't refresh in the viewport in Houdini unless you press the refresh option in the windows bar.

I'm converting a lot of my Max and Maya assets to Houdini, so it sounds like FBX might actually be better for now. When I get in to making actual scenes with new, "hand made" models I'll check USD out. I have no experience with USD in Max/Maya, but I will check it out now.

I know I had problems with textures, but now that you mention it I'm not sure what format that was. Maybe I stumbled on an error and assumed it was a general texture problem. Sounds like it was en EXR, then, thanks.

Thanks for the insights!

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