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Iray scene size.

bshugs1525871bshugs1525871 Posts: 183
in New Users

I looking for some guidance for Iray scenes, particularly as limited by a graphics card's memory.  I have a GTX 970 with 4GB which also drives my monitors (at least until I get a 1070/1080 which will be when they support Iray).  That takes up about 750MB to 1GB of video when Daz is running.  I see some beautiful sets in the store but combined with two, or even just one character I always seem to blow out my VRam and fall back to CPU rendering.

I've tried setting Instance Optimization to Memory and that helps sometimes.  From time to time, I recycle materials for clothing and even skin, just changing the Base Color to make it different.  Does anyone have any other suggestions while I scrape together the cash for a second card with 6-8GB VRam?  Should I just turn off the 970 and go straight CPU?   Is there any way to gauge how much video memory I'll need to render a scene?  Any easy way to conserve memory?

Thanks in advance for any suggestions.

Comments

  • TottallouTottallou Posts: 555

    I certainly would not turn off the GPU as the scene should fall back to CPU if it doesn't fit in the card anyway & CPU rendering is so much slower that you don't want to do that if there is any other option.

    I found saving the scene, closing Daz & reopening sometimes gets the render to use GPU - This only works when its close to the limit though & every little counts :)

    Often textures take up a lot of GPU memory, Many are 4000 x 4000 so depending on what you are rendering you can use photoshop or gimp to reduce the sizes - You can maybe remove normal/bump maps for areas of the scene that don't need as much detail.

    Other things I found eating memory are a high level of Sub D on something that again may not be needed if the image is not showing a close up of that particular character/item.

    Hopefully someone else will be able to add some more suggestions

     

     

     

     

  • BeeMKayBeeMKay Posts: 7,019

    The rule of thumb is, you can fit two dressed people with hair and modest background on a 4GB card. HD, large maps and normal maps eat up lots of memory. You can reduce memory load if you remove normal maps and HD for anything that's not a close up. Also, reducing the map sizes for the background stuff will "ease the load".

    If you have larger scenes, render in layers. Render, for example, the background first, and then as many characters without background as your system can handle. Compose them in your image editor of choice, like Photoshop Elements, or Gimp.

    I wouldn't switch straight to CPU; if you render in layers, you will get speed advantage from your card. Maybe switching your monitor view to the on-board video card would free those 750mb, and give you some more working space.

    I've made a rule of thumb that what you use as regular memory (check in the task manager, before loading anything into DS compared to your final scene) will be the minimum of what you will load to your card. Usually, with HD and normals, that will be more.

    I can recommend this tool: http://www.daz3d.com/iray-memory-assistant

    It's not cheap, but if you can grap it during a Simtenero sale, it's very useful in finding out what's eating most memory, if your scene has the potential to fit on your card, and use it to switch off items in the scene.

  • qeldroma91qeldroma91 Posts: 2

    I got the same GC and I ran out of Vram only twice in Iray : on a 10 seconds movie (253 pics 420*270p) and a still 4k render with 5 puppets... It never fail a 1440p render, but it means time...

     

  • bshugs1525871bshugs1525871 Posts: 183

    Thanks everyone for the feedback.  I'll try out some of the ideas.  Then again, when I get a better card that doesn't need to drive monitors...  wink

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