Iray Quirk?
MacSavers
Posts: 324
While Iray seems to be the direction Daz Studio is going, I'm still leery of it. I have a MacBook Pro with the nVidia 650m, so it's not the best chip to do this with. A render that takes around a minute with 3Delight takes over an hour with Iray, so I have to be selective it what I render with it.
The main issue seems to be materials and shaders. From what I can gather, you need to use different shaders for Iray than what works for 3Delight. Does this also affect materials?
I ran into a very strange issue where a character that looks just fine in 3Delight now has plastic hair in Iray. From a distance it's not really an issue, although the hair seems to wash out a bit with strands being much finer. But close up, it's clear that the hair is suffering from a plastic like reflection. This clearly isn't in the material or settings for the hair or it would have looked plastic in 3Delight. So this makes me think I need a completely different material and setting for hair in Iray than 3Delight.
I've included a rendered image to illustrate the issue.
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Comments
Yes, because the two renderers are completely different and don't even speak the same 'language', EVERY material needs to be different (whether autoconverted or have the Iray shaders manually applied). Some will convert easily and well, others...and this is a very common problem with hair, won't. Part of the problem is that the type of hair used in DS is a 'cheat' and a 'hack'. To work well in an unbiased/photrealistic renderer, this type of hair needs much higher quality maps than are usually supplied. One of the most common problems is that the transparency maps are 'color'...which confuses things when Iray is expecting a greyscale/b&w image for the control map (internally it's processed differently).
The other part of the problem, is that because there are no special shaders for hair, it's pretty much treated like other thing when the default surface is auto-converted to Iray. There are some hair presets for the Iray shader that provide a good launch point, but they will need to be manually applied.
Well, that creates a whole lot of extra work for every single render that I would want to do in Iray. I'm already looking at a 60-fold increase in render time. I tried to render a scene I did that took 3Delight one and a half hours in Iray. After four days and not a single pixel rendered, I had to give up on the test. Now you are saying that I have to test render in Iray to check to see which textures need updating, not even talking about the amount of time learning the lighting requirements since the 3Delight lights don't work either, it appears that I might be wasting my time on something that will never truly be usable for me.
It's a shame really. There's tons of potential in Iray, but the time requirements seem unproductive at this time unless you have the equipment to handle it, which I obviously don't have and unfortunately won't be able to resolve for some time. I was especially excited about finally being able to use glow panels like I do in other 3D programs that render closer in speeds to 3Delight.
For now, it appears I will have to put this in the "play with when I want to waste time" category. It's just not productive enough at this stage.
The no pixels in a long time period...that WAS a bug in an earlier version of 4.8. It was something with the default settings not playing well with a wide variety of machines. The defaults have been changed in the more recent builds. I can't remember, exactly, but I think you need to change the Memory Optimization setting, in Iray render settings.
As to lighting, again the most recent build just got a thousand times easier...the default lights are now 'dual purpose' lights. In 3DL, they behave just like they always have...in Iray, the Iray specific settings are exposed and the 3DL ones ignored.
A 650M ***should*** be able to have GPU accelerated renders...I've rendered (up to memory max) on a 1 GB 440GT with GPU acceleration.
Skin and hair are the two areas that usually need the most manual intervention...simply because they use the same shaders as everything else, but are vastly different than most things. Metals, glass and some other items are best converted by applying the Iray Uber or one of the included presets...but it's quick to do, with minimal fussing with the settings from the preset. It's actually a lot less work than optimizing Poser only materials or even converting to Luxrender or Octane.
I tested the GPU versus CPU renders and they came out almost at the same amount of time for the render. I haven't tested the latest build, so perhaps it's time to test it again. Once the 4.8 release shows up on DIM today, I'll give it another test. Unfortunately, my 650m only has 512mb of cache RAM. As much as I love my Mac, I do wish Apple would offer more GPU choices. Still, I'd rather live with my Mac than have to deal with the alternatives.