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Delay at the beginning of iRay renders: Conversion of materials?

PA_ThePhilosopherPA_ThePhilosopher Posts: 1,039
in The Commons

Hey guys,

As you know, there is often a long pause at the beginning of iRay renders, after step 1 (after the log says "compiling shaders").

I would like to minimize this delay as much as possible, and was wondering if converting all materials to iRay Uber Base would make a significant improvement in this. Or if not, if there is anything else I can do to help.

I have also noticed sometimes that using the GoZ plugin too much can result in significant slow-downs in rendering. One time I created a few morphs on an object (elongated a piece of clothing) in zBrush, and my render time increased three-fold. As soon as I deleted the modified object from my scene, my render times went back to normal again. I am guessing that there was some issue with the geometry of the morphs that Daz didn't like, even though the number of polygons remained constant. So its not all about polygon count. 

Thanks. 

Comments

  • ToborTobor Posts: 2,300

    The added time is Daz and Iray constructing the scene database. This includes conversion of materials, if they are not already Iray-compatible. For reasons of not just shortening the startup time, you should avoid using non-Iray shaders, which means manually applying the appropriate Iray shader to everything in your scene. The result of the just-in-time shader conversion is not predictable, and you have limited (at best) control over its appearance.

  • grinch2901grinch2901 Posts: 1,247

    Even if I select all materials and convert to Iray uber basic, I still get that long delay.  I began to watch what was happening using GPU shark and noticed that as the delay is going on, the mempory load in my GPU increases for a short time than stops while studio churns.  At this point it's maybe only 200K memory usage in the GPU.  I'd dare say that this does not yet include textures.  Then after churning for a while it jumps up to the final value (in my scenes usually just below 2GB which is all I have).  So what do I conclude from this?  Well, I can't say it for sure but I suspect it has to do with Iray's texture compression.  It's cranking along compressing textures before it loads them onto the GPU, which takes time even if the shaders have already been converted previously.. 

    Am I right?  Who knows.  But that's my theory.

  • fred9803fred9803 Posts: 1,565

    You're a brave person indeed to use Iray with 2GB of RAM. Cheers.

  • PA_ThePhilosopherPA_ThePhilosopher Posts: 1,039
    edited January 2016

    Grinch,

    I have found the same as well. Even if I manually convert all object to iRay uberbase, it does not change render time at all.

    As an aside, I did notice one significant thing however. I can reduce the initial delay from 45 seconds down to 6 seconds by simply initiating the render while the viewport mode is on iRay. Evidently, whatever work the CPU does in the iRay viewport is automatically transfered (and thus not repeated) to the render. 

    A final Question: I am curious if anyone has experiemented with Daz 4.9, which has the latest version of iRay. It is supposed to have speed improvements, according to the change log.

     

    .

    Post edited by PA_ThePhilosopher on
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