Does BB's hair shader slow rendering down?

  • @eclark1849 said in Does BB's hair shader slow rendering down?:

    @amethystpendant Run it with the caustics off.

    I was testing the settings provided by @glossaphile and @ghostship they aren't my settings

  • @amethystpendant As I understand it caustics wont actually increase render times, they will increase the noise IF there is stuff that shows off the effect prominently. If you got a spotlight shining through a glass of water onto a table you will see the caustics effect and that might need a bunch more samples to resolve.

  • I just tried a render with Ghostship's settings, and I don't think my computer likes them at all. A 300x300 test render with hair froze my computer to all but a standstill. I couldn't even bring up the Task Manager properly, and that was with a foreground render. When I tried to "Render in Background," I ended up having to reboot my laptop (though that may have just been a fluke).

    Plus, the end result was noticeably noisy and took roughly just as long as the same render with my own current best attempt at optimal render settings (about half an hour).

    Ghostship, I appreciate your patient help, but in this case, I think you might just be too used to dealing with a six-core processor. Either that or there's something fundamentally wrong either with my system or with my procedures. In any case, I'll be cautiously tinkering with them to see if I can come up with something that works for me.

  • @glossaphile same settings I used on my i5 2500.
    At the very least you should follow some of the other suggestions I made. They are sound. You could also lower the max bounces and trans bounces to 16 and start with a small sample setting (like 5)

  • @ghostship I did. I'm now running 4 threads instead of 8 with "Separate process" turned off. I tried lowering Max Bounces and Max Transparent Bounces to 16. My bucket size is also 16. I've even simplified the hair shader, making it a hybrid of yours and BB's. I will now try just using your unmodified shader, which I think is the only major suggestion left.

  • @glossaphile Cool. Keep us informed.

  • Okay, here's the comparison of the same 300x300 image with hair.

    With My Current Best Settings and Shader: about 32.5 minutes
    With Ghostship's Settings and Shader (with MB and MTB tweaked to 16): about 34 minutes
    With My Settings and Ghostship's Shader: about 37 minutes

    I should note that the results of using Ghostship's settings produced mild but quite noticeable noise, particularly on the skin, though I suspect that's from Reflective Caustics, which could easily be turned off.

  • @glossaphile I would double check your settings, especially your filter glossy and clamp setting as both I and @amethystpendant got better results with my settings than yours. Probably don't need the caustics on as there aint much that needs it when you are rendering a human.

  • @glossaphile another thing that could speed up your renders is using a sky dome instead of the default ground. Turn off the ground/construct in the hierarchical menu and load up EZDome or @bagginsbill Enviroshere and light it up with a JPG (low res JPGS will give you less noise) keep the brightness fairly low and adjust your lights if you need to. Using environmental lighting like this will use less diffuse bounces and the render should be quicker and less noisy.

  • @glossaphile Here are my tests. One with skydome and the other with the default ground/construct. The one with the Envirosphere took less time and has better lighting. Every little bit counts and adds up to a better and faster render.
    0_1525411715102_Light test enviro.jpg

  • @glossaphile Did you drop the threads to 4 as suggested?

  • @amethystpendant Yes, I did.

    I think I've hit a sweet spot of sorts. With Ghostship's hair shader and these render settings...


    ...I managed to render this image in just about 5 hours and 6 minutes.


    Actually, prior to tweaking the hair texture map (which shouldn't have noticeably affected render speed), what was otherwise the exact same image with the exact same settings rendered in about 4.5 hours overnight. I suspect the difference was that, the second time around, I diverted some of the processing power to other tasks (YouTube videos, etc.) while I waited.

    My character is actually placed in a a whole indoor photo studio scene, so a sky dome is moot for me. Theoretically, I could use one of BB's utilities to generate a panorama for a sky dome from the original studio setup and use that, and I may yet try it. Regardless, the current render time is over 4 hours shorter than my last best attempt (9.5 hours)!

    I must confess to a bit of a hack with the hair texture. I took BB's mathematically generated hair texture (without any color) and rendered it on a prop square with the camera zoomed just right so that it filled the viewport. After a bit of editing in Photoshop to enhance the contrast, I then plugged that render as a texture map into Ghostship's shader, using it as a bump map and as a bias map, the latter of which was combined with a simple input color to form what would otherwise be the diffuse texture map.


    I use a Color Ramp for the base color just because it makes it easy to switch between the cardinal hair colors (black, brown, red, and blonde).

  • @glossaphile
    @amethystpendant said in Does BB's hair shader slow rendering down?:

    @glossaphile Did you drop the threads to 4 as suggested?

  • @amethystpendant Like I said, I did reduce the thread count to 4. It's been 4 for the last few renders now.

  • @glossaphile have you reduced the thread count to 4???? LOL

  • @glossaphile Ok, hard truth this time. If it isn't getting rendered, it is wasting your time. What do I mean? I'm presuming you are using a room prop and some tripod/lighting/camera props that would normally be seen in a render and be interacted with by your figure. If the props aren't actually in view of the camera they are making more work for you than you need. All that stuff is going to need diffuse/reflect calculations that will just slow down your render and not really give you any appreciable benefit. As I pointed out before, use a skydome with an interior HDRI image. Even a bedroom scene will work. Your lights will still reflect in your figures eyes just as they should but now you'll be getting proper ambient light from the dome and save render time. Every time a sample hits an object that has diffuse it calculates it's color and then bounces to the next object in it's trajectory. When a sample hits a light source it makes it's final calculation and stops: it's done it doesn't need to calculate anything anymore. Since your camera isn't actually pulled back to see the room it would be advantages just to use a skydome and HDRI. I've already pointed out that you'll get a better image and save time. Why not try it? you really are not going to get a superior rendered image by placing your figure in a room prop with furniture and studio equipment props.

  • @glossaphile Here is what I do for studio lighting.
    0_1525497772966_Studio lighting 1.jpg
    0_1525497791928_Studio lighting 2.jpg

  • @glossaphile Ok here is an instance where I used a room model. All the lighting on this is mesh lighting that is built into the model no lights or skydome for this.
    0_1525498692352_Car Expo.jpg

  • @ghostship said in Does BB's hair shader slow rendering down?:

    @glossaphile have you reduced the thread count to 4???? LOL

    I've answered this question affirmatively twice now. Are you not getting my answers?

  • @ghostship Really? I thought an object had to have some influence on how the visible objects look (via reflection, indirect illumination, etc) before it would trigger any calculations.

    I'll experiment with a panorama/dome version of my studio arrangement tomorrow. BTW, stunning car render!