Excruciating transparency rendering



  • Why is Poser so utterly UTTERLY sh*t at rendering multi-layered transparency?
    I converted the Axel hair style from DAZ. Without doubt, it's a very complicated style - dozens if not hundreds of overlaid billboard strands, each textured and trans mapped - definitely a processor heavy hairstyle, arguably poorly designed. However, in DAZ, you can get something reasonable from the renderer in under a minute, although it may well take 15 minutes to get a completed IRay render. In Poser, using Firefly, a minute isn't even enough time to finish preparing the image for render at medium quality, and 15 minutes doesn't even get you a centimetre square of render. And that's without all the additional complexity of the DAZ render such as top coat, glossiness, reflectivity, translucency, and more.
    It's clear that Firefly is not a fraction as fast as IRay. , but I had hoped that it could at least be within 10 divisions of 3Delight.
    0_1511490789758_axel.jpg


  • Poser Ambassadors

    Your comparing apples to BMW's here.
    Octane, Furryball, and a few other engines can do final renders in mere seconds.
    Does that make Iray junk then too?

    The key to any render engine, is knowing its design, and how to use it.



  • @shvrdavid Hey shvr I would think that comparing a free renderer to a dramatically worse one in a £400 product, when both products operate within the same consumer space was wholly reasonable. But if not, then only because I'm being overly kind to Poser's renderer.

    But if you have suggestions about how to improve my Firefly render times with this specific product's trans mapped hair, I'd certainly appreciate hearing about it. Thank you.


  • Poser Ambassadors

    Oddly, but not surprising at all. Your initial post did not ask a single lagit question.
    The wording of your post, well its typical.

    Your comparing an cpu based engine from years ago to a gpu engine that uses thousands of cores.
    Worse yet, one that the shaders are obviously not set up.
    And in the process, you did nothing but bash.

    Maybe if you would ask a specific question without bashing, comparing, etc.
    You would get an answer.

    Try again in about a week.



  • @matb I'm thinking that you meant to say SUPERFLY and not Firefly. in that case @shvrdavid has a trick to get around long renders with hair. I tried it once and it does shorten render times but it also affects light bounces from hair onto surrounding skin.

    https://forum.smithmicro.com/topic/2067/rendering-transmapped-hair-in-superfly-very-long-render-time/6



  • @matb Also, could be the shader setup being inefficient.



  • @ghostship Thanks for the thought Ghost, but no I did actually mean Firefly.



  • @matb Yes, I would say that Firefly is slower at hair rendering than Superfly. One thing that some people try is turning off cast shadows for the hair (in it's properties) that will make it render lots faster but it will look cartoonish.



  • @ghostship said in Excruciating transparency rendering:

    @matb Yes, I would say that Firefly is slower at hair rendering than Superfly. One thing that some people try is turning off cast shadows for the hair (in it's properties) that will make it render lots faster but it will look cartoonish.

    Unchecking "Visible in Raytracing" for the hair can also be beneficial in speeding up the hair render in FireFly, though it's probably not something I'd do for a closeup. Never tried that in SuperFly though.



  • @Deecey I think it has the same visual effect: no bounced shadows or something similar. Make the hair look like a cartoonish blob. Sure does speed up the renders though...



  • IMO, unchecking "light emitter" properties/whatsits for the hair geometry greatly speeds up rendering in multilayered, complex, geometry like strip hair and its transparencies. There's little real need for that in normal Firefly renders for hair. Imagine all those transmapped strands getting caught up in a photon bounce-war... horrendous! Oh, the humanity! The poor photons...

    Doing that will have immediate results in the speed of the next Firefly render, guaranteed or your money back!

    <Current Market Value of post= $0.00>


  • Poser Ambassadors

    Light emitter means include in IDL calculations; unchecking this for any complex geometry will save time in the pre-calc stage.

    AFAIK the problem with multiple overlapping transparencies is called overdraw.

    Brief explanation on the Polycount wiki & here's a good one from a Polycount member called marks in this thread on the forum which I'm gonna shamelessly copy/paste:

    "1-bit alpha also causes overdraw on every pixel, even the opaque ones.

    With 8-bit alpha opaque pixels are just as expensive as partially transparent pixels. When it gets expensive, is when you have several layers of alpha cards on top of each other - because with opaque pixels, the render does this:

    Render the pixel - oh cool it's opaque, draw it to the framebuffer.

    When the pixel you're drawing has multiple layers of transparency, you get this:

    Render the pixel, oh it's not opaque. Render the thing behind it aswell. Oh it's not opaque. Render the thing behind that. And again. And again. And again until your pixel becomes opaque or you run out of objects.

    You basically have to render the same pixel multiple times. Which is why it matters how big your alpha stuff is relative to the screen size. If you have alpha which is covering a lot of your screen (eg covering a lot of pixels per frame) then that's gonna be mega expensive because there is a large percentage of the pixels in your frame need to be rendered multiple times.
    If you have like 20 layers of transparent polys, but they're really small in screen-space and not covering many pixels on the frame - that's kind of okay. If it's like 2% screen-space coverage, don't even worry about it..."

    Which means that the way the mesh is made (the size of the transparent areas relative to the geometry) plus the size of the mesh in the render will impact on render time.

    It also means that a lot of render engines will struggle with overlapping transparencies.



  • @matb said in Excruciating transparency rendering:

    Why is Poser so utterly UTTERLY sh*t at rendering multi-layered transparency?
    I converted the Axel hair style from DAZ. Without doubt, it's a very complicated style - dozens if not hundreds of overlaid billboard strands, each textured and trans mapped - definitely a processor heavy hairstyle, arguably poorly designed.

    I think that hair looks fantastic without any transmaps. Even a solid style like the one above looks excellent. The only area that I think requires a transmap is skin areas, and maybe they will look great by making them fully transparent.

    Good job!