Iray newbie

SteveM17

Hello,

I've always rendered in 3delight, on the couple of times I tried to use Iray it seemed to take so much longer that it wasn't worth the wait. But I'm still tempted to try it for the better results (assuming iray is generally better). So I loaded a simple figure, no clothes or hair or anything else and hit render in Iray. The progress box came up with a list of Iray iterations and "target canvas was written" and the percentage bar stayed at zero for about 13 minutes before slowly starting to move. Is that to be expected, considering that if I'd done that render in 3Delight it would have probably finished in less than a minute? Is there a way to know how many iterations (what ever they are, but I'm assuming they are what take up most of the time) there are going to be in a scene before rendering and can that amount be altered? Iray renders look great, but the amount of time seems excessive. Am I doing something stupid?

Any pointers would be appreciated, as I know very little about Iray.

Cheers

prixat

Without an nVidia graphics card to accelerate the process to the amazing times you may have seen in the benchmarks, you're stuck with the CPU only.

PerttiA

Do you have Nvidia GPU and how much VRAM does it have?

margrave

Iray has a completely different approach to rendering than 3Delight.

Since real life light is too complex to compute effectively, for every iteration Iray will shoot out a bunch of light rays and examine how they bounce around the scene. It "samples" how the light will behave. These samples are then blended with the previous iterations, refining the image quality. The progress bar you mentioned simply measures how far it is to the Max Samples in the render settings. You can change it to whatever you want.

Iray is never "done", per se. You render it until it looks good.

If you enable progressive rendering, then the "Rendering Converged Ratio" slider will stop the render once it reaches the point of diminishing returns (assuming it doesn't hit Max Samples or Max Time first).

y3kman

While you could do an Iray render with any CPU, it is highly recommended you use an Nvidia GPU with at least 8GB VRAM. Iray is an Nvidia tech. Meaning if you have an AMD video card you're out of luck.

Your scene also needs to fit within your card's VRAM. If it doesn't, the renderer will use the CPU as a fallback and that would result in a slow render.

 

SteveM17

I'm not sure what vidoe card is being used for Daz, the sticker on my laptop says I have Nvidia Geforce. When I look on Task manager it shows GPU0 Intel (R) HD  and under that is GPU 1 Nvidea Geforce but that doesn't seem to be in use. On  Daz when I go to check video card I get the following :

Current OpenGL Version:	4.3.0 - Build 20.19.15.4642
OpenGL Provider:	Intel
Hardware:	Intel(R) HD Graphics 4400
Features:
MultiTexturing	Supported
Shadow Map	Supported
Hardware Antialiasing	Supported
OpenGL Shading Language	Supported
Pixel Buffer	Supported
Pixel Buffer Size	Not Enabled
Maximum Number of Lights	8
Number of Texture Units	8
	So I'm thinking maybe I'm using the wrong video card and that could be making the renders for Iray longer? If so how do i change that? Clearly I don't know much about this side of things, any info is appreciated.

Richard Haseltine

In task manager you need to set one of the performance graphs to show CUDA (or Comnpute_0 if you don't have CUDA as an option) - by default Task Manager does not show Iray activity.

SteveM17

So I've been looking at my graphics card and it seems according to task manager for my Nvidia card I have "dedicated GPU Memory" - 2GB and the system says I have Display memory of 1999mb , which seems to be the Vram I think. How do I know which card Daz studio is using, or how do I switch between GPU and CPU?

Thanks guys.

EDIT:  I've unticked the boxed in settings that say CPU so it should now be GPU only. The test iray render seems to have got off to a quicker start, but the progress is still slow. I'm thinking if I lower the max samples or the max time that would speed it up, although the image wouldn't be quite as good (but I can live with that). What settings for samples or time would you guys recommend?

Richard Haseltine

2GB is very little, I fear it would take almost nothing to exceed its capacity.

PerttiA

One G8 character with lightweight clothing and hair in an otherwise empty scene already requires 3GB's of VRAM to render in IRAY

SteveM17

So it seems that until i can afford a new computer with a better graphics card I'll have to stick with 3Delight. Oh well, time to look for a new job!

Cheers for the info everyone!