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Hair in iray - longer renders?

jakibluejakiblue Posts: 7,281
in The Commons

Has anyone had a hair in iray that they think is bogging down the render times? 

I've got an iray render that is taking an awful long time, which is unusual for what it is, and I've not experienced before. 

I'm wondering if it's the hair. 

I'm using hte Big Afro Hair with the UHT Hair shaders on it, and it's the only thing in the scene that I can think that would be bogging down the render. 

If it is, are there any tips or tricks to help it get along a bit faster in iray?

Comments

  • fred9803fred9803 Posts: 1,565

    That looks like a fibermesh hair though I could be wrong. If it is, there's your answer for the render times.

  • jakibluejakiblue Posts: 7,281

    oh bums, i think it is. 

    Damn. 

    Is ther anything you can do in iray to help it along? I remember in 3delight that you using the uberhair shader and changing something or other could help with hair. Wondreing if iray shaders have something similar

  • fred9803fred9803 Posts: 1,565
    edited April 2016

    The hair is holding up your whole scene from rendering. This might be a bum steer but I would render the scene without the hair, then do a spot render of just the head/hair and patch it into the scene render. It's debatable whether this will be quicker but I actually think it is from personal experience.

    Edit - I suppose I better qualify that suggestion by saying that if it is a close up and the hair is taking up a large proportion of the scene, the method I suggested probably won't make any difference. If it's a full body shot then it should be quicker.

    Post edited by fred9803 on
  • jakibluejakiblue Posts: 7,281

    when i spot render, it doesn't render to another window/file for me to save it separately...how do you do that? 

    yep, it's a full body, not a close up so that would work

     

  • fred9803fred9803 Posts: 1,565

    I'm rendering right now so I can't look, but I think you select the spot render tool, go to Window, Panes, and down the bottom of the list you should have Tool Settings. There you can choose to render to a seperate window and save it.

  • scorpioscorpio Posts: 8,533
    edited April 2016

    I'm not finding that its seeming to take any longer than other hair, have you used Iray surface shaders, also lights make a big diference for me I find mesh lighting relly adds to the ender time. I'm rendering with CPU only.

    To render to a new window for a spot render when you have the spot render tool selected go to the tool tab and theres a choice there to render to new window.

    Post edited by scorpio on
  • isidornisidorn Posts: 1,601

    Just adding in a confirmation that hair indeed can slow down render times. Some PA's that has done particulary troublesome hairs have even been nice enough to warn about it on the product page.

    As for the big afro hair, I've been tinkering with a render lately that has two characters with that hair and it renders pretty fast. I'm not using the UHT shaders though.

  • j cadej cade Posts: 2,310

    I'd try it without the UHT shaders Fibermesh hair tends to have its uvs setup such that traditional textures dont really work. (also I think UHT shaders use displacement, which on something as already high poly as fiber hair will bring your computer to a crawl)

  • Oso3DOso3D Posts: 15,085

    If you use UHT on fibermesh, you want to get rid of all the maps, I think.

     

  • outrider42outrider42 Posts: 3,679
    Yeah, I remember testing some different hairs I bought and downloaded, and some of them drastically effected render times. I had a character that rendered in 2 minutes with no hair, that jumped to 3-5 for most hairs. However, I tried a free Afro I found on Sharecg, and my render time was destroyed by it. That same character was at 1% after 5 minutes where other hairs would be finished.
  • Kev914Kev914 Posts: 1,126

    I have one hair that does this. I think it's the Brian hair. In 3dL, it will render around the hair and complete most of the scene as the hair fills in little by little. I can't remember what happens in Iray, but I'm sure I didn't wait for it to finish. The hair looks nice, but it just takes too long to render. I don't think I've every completed a render using it.

  • mjc1016mjc1016 Posts: 15,001
    j cade said:

    I'd try it without the UHT shaders Fibermesh hair tends to have its uvs setup such that traditional textures dont really work. (also I think UHT shaders use displacement, which on something as already high poly as fiber hair will bring your computer to a crawl)

    Not to mention adding Opacity maps to all those hairs...OUCH!

     

  • mtl1mtl1 Posts: 1,508

    You could try decimating the mesh and see if that will help the render times... in theory, a decimation wouldn't hurt a fibermesh as much, right?

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