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Author Topic: GPU memory inconsistency and CPU questions...  (Read 2783 times)

Integr8d

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GPU memory inconsistency and CPU questions...
« on: February 25, 2015, 03:39:31 AM »
Hello all. Newb, playing with the demo. Fun stuff...

As seems to be the case, performance is the issue with photogrammetry. Always trying to eek more out!

I'm running a modest rig (i5 Haswell, 8gb ddr3, 2x r9 290's) and am curious about the gpu stage of mesh building... Specifically, I see the cards in Prefs. But it's interesting in that it reads one of the cards as having 4gb ram and the other as having 3gb. Has anyone seen that?

Also, when decreasing the core count, to give deference to the gpu's, is that only for the portion of meshing where the cards are used? And will all cores be used for all other stages? Just occurred to me that I could just watch it in task manager. But if anyone knows off the top of their heads...

Lastly, and I'm going to pay closer attention, once the current alignment is complete, has anyone observed (via gpu-z or some other h/w monitoring app) their gpu's actually coming online for the mesh stage?

Thanks all for looking. Just reading through some threads, I can tell that this is a pretty cool community.

Integr8d

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Re: GPU memory inconsistency and CPU questions...
« Reply #1 on: February 25, 2015, 11:11:16 AM »
Answered one of my own questions... The video cards definitely do turn on for the first half of the depth map generation. Interestingly, with 2 cpu cores disabled, the video cards seem to be under load in spurts. They're not steadily under load. Is that typical?

Marcel

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Re: GPU memory inconsistency and CPU questions...
« Reply #2 on: February 25, 2015, 08:58:41 PM »
GPU load is in spurts, that is correct. Also note that Photoscan uses only a specific part of the GPU, for this reason you might not see 100% load either.

The CPU cores option applies only to the Dense Cloud stage (because that is the only stage where the GPU is used). Other stages (Alignment, Meshing, Texture building) use all available processing power because they are CPU only.

I've got it set to use zero cores, because the CPU doesn't do much anyway. Also, when it's set to zero cores I can start a second Dense Cloud reconstruction as soon as the first enters the "Depth Map FIltering" stage. So you can overlap processing of two projects without much slowdown.