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3D View Strangeness

ebergerlyebergerly Posts: 3,255
in The Commons

So this is weird...

I've got my 3d view set to Iray. While it's just sitting there my GPU is at 100% utilization as expected as it renders the 3d view. 

However, as I start to navigate/rotate the view the GPU utilization drops to near zero as long as I'm moving the view, and when I stop it restores to 100%. Strange.

And the CPU 's 16 threads don't seem to change much, though overall CPU utilization goes from about 7% to maybe 14% while I'm moving the view.

I always assumed the GPU did all the heavy lifting in the 3d view. 

Anyone know what the deal is? 

Comments

  • TooncesToonces Posts: 919

    Personally, I like that behavior. I don't want my GPU to work overtime when I'm just moving around. However this thread has some tips on how to get more immediate drawing. Excerpt:

    To reduce the IRay preview lag, then you need to go into the Draw Settings Pane, switch the DrawStyle to NVIDIA Iray, and then look at the "Drawing" options

    Change "Response Threshold (msec)" to a much bigger value, like 5000. The "Inactive Viewport Delay" should be "Off"

    I find with these settings the scene refreshes much more quickly, and you avoid the long periods where the whole view goes grey.

  • ebergerlyebergerly Posts: 3,255

    Thanks. Yeah, I already have those settings, and in fact I posted in that thread praising Havos for posting those settings. 

    What's strange is if you're NOT moving around the GPU is at 100%, and as soon as you move it drops to zero. So I'm not understanding the benefit of dropping to zero and losing the render speed. 

  • ebergerlyebergerly Posts: 3,255
    edited October 2017

    By the way, in case anyone is interested, here are the 3D view Iray settings which IMO are key to making sure your 3D view manipulation response is fast as possible:

    1. Render Settings/General/Auto Headlamp = Never
    2. Draw Settings/Drawing/Response Threshold (msec) = 5000
    3. Draw Settings/Drawing/Inactive Viewport Delay = Off
    4. Edit/Preferences/Interface/Display Optimization = Best
    5. Use Perspective View when manipulating, since any Camera view is generally much slower, especially if you have a light parented to the camera like a headlamp
    6. Avoid using "Point At" if you want your character's eyes to point at the camera. That will slow the camera view manipulation a lot. 

    The first one I came up with after finding that for some reason headlamps slow things down a lot. Thanks to Havos for opening my eyes on the others, they make a HUGE difference.   

    Post edited by ebergerly on
  • ebergerlyebergerly Posts: 3,255

    Wow, so this is real strange. Turns out I broke my own rule and had Auto Headlamp = ON when I got the strangeness of the GPU shutting down when moving in 3d View. But when I turn Auto Headlamp = OFF, the GPU load stays at 80-90%+ as I manipulate. And the response is MUCH faster. 

    Apparently the headlamp causes bad things to happen with the GPU? 

  • TooncesToonces Posts: 919

    Not just headlamp. Probably happens with any light source.

    When I'm in Iray mode, moving lights slows things down momentarily...much more than just moving camera or perspective view. Since Iray is highly dependent on light placement for its various calculations, I figured it made sense.

    Nice tips btw. I like the display optimization one. Surprised it's not default since it's so useful.

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