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From a few simple tests, just having Mantra render a large # of high res EXRs takes forever and uses a lot more RAM than having pre-converted the textures to rat files (EXRs - ZIP, Multi-scanline blocks).  So that makes me want to pre-convert all our textures to rat files automatically.

 

I'm interested in how other places handle texutres in their Houdini pipelines.  Is there better ways to export out 

 

Do you normally convert them to rat files and then render them?  How do you keep the rat and exr in sync?  Or do you let Mantra always do that for you? 

 

 

 

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rat's can be a blessing and a curse.  rat's allow random access to your texture so they don't get loaded all at one time.  however, if they're on a slow-ish network drive, you might find the random access ends up causing slowdowns.  there are flags and toggles designed to mitigate this, but if you leave things as exr, you get the conversion cost, but you then have all the data locally...

 

you might consider a cheaper exr storage, perhaps.  ideally, mantra would do the conversion to disk rather than ram so you wouldn't suffer a ram hit...

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I usually use mplay for that. No way using exr or tiffs for texture heavy scenes. When you have UDIMS you can treat them as an sequence and batch convert them. Otherwise you'll unfortunately need a custom tool if you need more automation. don't let Mantra do that for you. actually, mantra is doing that every time you feed in different file type than rat and that is what slows down your render and eats up all the memory. the process, unfortunately, seems to be not very efficient and other than keeping a huge amount of data in memory while rendering, converted files are not kept so mantra will keep doing this for every frame. shame :-(  

 

I keep exrs and rats in the same folder which is never overwritten. If textures are updated they are stored in a new folder with a version number. that way, rats are always synced with whatever exrs are in that folder. in Houdini scene, all textures are referencing path from a single source (typically a null with parameters) so it is very easy to update textures for the whole asset or its part, go back a version, render different texture version for each shot or whatever.

Edited by davpe

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I like how Arnold handles this - when a texture is requested that is not a ".tx" file, it checks if there is one in the same directory "foobar.exr -> foobar.tx". If there is a tx file, it then checks to see if the tx is outdated. If it is not outdated, it automatically uses the .tx file.  If it is out of dated (or missing), it creates one, and then uses that.

 

I was really hoping there was a hidden preference to have Mantra do something similar... 

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