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Rat usage and -m flag help


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Hello everyone!

Could someone please help me understand a few things on the render optimization page here?

For starters, under Rat Usage it suggests changing that global variable (which I just learned how to do, huzzah) to something more than 32 mb. In the command line tools, the variable HOUDINI_RAT_USAGE is at "256". I suppose that's.... plenty?

Also, what does it mean/where do I find these mysterious "Flags that will make my day"? The -M flag, the one that increases the Ray Mesh cache size, sounds promising, but honestly I have no idea where that would be and for some reason googling it is failing me :huh: (I've probably just been working way too much to function any longer).

One super-dumb question: I added a GIlight to my scene (r. 11), specified a location in the Photon File slot, set my render node to Photon Map Generation, and made a .pmap sequence. It is that same Photon File slot where you specify the map, yeah? As far as I can tell, the documentation is dated on sidefx's site :( I had an error earlier and I couldn't tell where it was from, embarrassingly.

Okee dokee. I've appropriately set up lights in light linker, reduced the sampling to as much as is tolerable, made/tried to make a photon map, and made all my textures rats. Is there anything I'm missing that's good practice to speed up renders? Any corners I can cut that I'm not thinking about? They're still a bit on the long side... I'll post a scene file if someone thinks it'd help...

Thanks a super ton everyone. Almost done with my first Houdini project! :D


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Oh dear, sorry, I just found this post--in his question he talks about using the -M cache, so I think I got at least that covered now...

Edit: Scratch that. When I input "mantra -M 16000" or "-M 16000" in the command line nothing happens because, obviously, I don't know what I'm doing :lol:

Edit2: (Using PBR, btw; samples set to 7/7 and, in a few rare scenes, 12/12)

Edited by Whithers
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Ohhhhh in the Command slot on the Main taaaaaab. Got it.

That helped a lot. How high can I set this with 48 gigs of RAM?

Clarification: I figured out how to increase the ray mesh geo cache size with the -M [number] command, but am wondering how high you can safely set it with said RAM, and am still wondering if maybe there's anything else I'm overlooking in regards to render optimization? The frackin lights in my scene take a particularly long time (should I just be using area lights for PBR? Or... hmm)...

Edited by Whithers
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