Iray render slower than 3Delight

yagakisan

Hi,
I' ve read about faster rendering with Iray, but with a simple scene without any lights I see that Iray is much slower than 3Delight.
I render animations and every frame with 3delight takes let's say 10-15 seconds where with Iray it takes not less than minutes.
I have a Nvidia 970 GTX.

Are there other settings to enable this claimed speed?
I' ve already tried to use Iray shader without success.

BeeMKay

A Titan X graphic card (or better, several of them), for example, accellerates rendering times by quite a bit. :-P

But seriously, if your scene is bigger than your VRam (which usually is the case if you have two characters in it - like, my card has 2GB Vram, but still isn't used very often, because it can't hold the scene), your render is falling back to CPU.
CPU can be accelerated a bit by Optix-activation, and if the scene is properly lit by a good HDRI (shut off the headlamp of your cameras!) it will shave off a bit. I've heard that rendering bigger images instead of smaller images will improve render times as well, but I can't confirm that.
I rendered a very simple animation using a single G2male walking around, and that took me 45secs per frame, by cutting it off at 250 iterations. Another one using 3 robot characters in it and an actual scene came out at 80 secs per frame.

EDIT:
Just for the record, this is what DAZ oddicially has to say about a good Iray system:
https://helpdaz.zendesk.com/entries/67520170-System-Recommendations-for-DAZ-Studio-4-

GPU (Graphics Processing Unit): With the latest public beta (DAZ Studio 4.8) the GPU plays a HUGE role in the render time when using Iray (the default renderer in DS 4.8). The GPU plays two roles, it determines how fast you can move geometry around in the interface and it adds processing power to the render process (reduces render time) with Iray (included), Octane (plugin) and Reality (plugin that uses Lux render). Let’s ding into the GPU as a few factors come to play.
•GPU memory has no direct effect on render time, it simply determines how big a file you can work with. We found that 2GB can handle a single character with a medium sized environment, 4GB can handle around 4 characters and a scene so we recommend 4GB and up. If you have two GPUs and they have 2GB each it does not add up to 4GB, each card has to hold the entire scene. If you try to render a file that is too large to fit in the GPU, Iray will use the CPU to render (which will be much slower than using a GPU or both GPU and CPU together). So GPU memory is what determines if the GPU can be used or not, if the file fits, it will be used and if the file doesn’t fit, it won’t.
•GPU cores, this is similar to CPU cores but instead of having 4,6 or 8 cpu cores running at 4000 MHz, you have thousands of them but they run at around 7000 to 1200 MHz. Each core can calculate a par tof the image so render time (with a gpu based renderer) is directly proportional to how many cores you throw at it. Iray is an NVIDIA technology and uses CUDA cores which are found in all NVIDIA GPUs, This means AMD (or ATI) GPUs will NOT be used for rendering with Iray, they will however come into play in the OGL viewport when you orbit around your scene (in drawstyles other than Iray). You can use one or multiple NVIDIA Geforce, Quadro and Tesla cards (or a mix of Quadro and Tesla) to decrease your render time with Iray and current cards tend to range from 250 to 3000 CUDA cores so there is a huge range of performance (and pricing) to pick from. The biggest setup that is available today as I write this would be using four NVIDIA Geforce Titan X cards which would give Iray a total of 12,288 cores to render with and 12GB per card would accommodate very massive scene files. Even entry level cards with 300 or 400 cores are substantially faster at rendering than current high end CPUs.
•There is no tangible difference in render time between Quadro, Tesla and Geforce cards, the specs that matter are how many cores and how quick they are (Geforce tend to be a little faster).

To decide what computer to go with I would use the following guidelines:
•Make sure your motherboard has the latest Intel chipset (currently the X99)
•For graphics applications 32GB of RAM is a good minimum, most high end systems have 64GB but this will have little to no impact on your render time.
•6 core CPUs are enough if you are going to use Iray (or other GPU renderer), when you get into high core count GPUs, the CPU becomes less important.
•Get as many large GPUs as you can… 4GB or memory is a minimum, over 8GB is probably not going to be needed. Core count is critical, so if two less expensive cards give you more cores than one expensive card, go for the two cards…

· Make sure your motherboard offers at least 8 lanes of PCI per GPU installed (Ideally 16 lanes per GPU). If you have 16 lanes per GPU you get the full performance, having only 8 lanes per GPU gets you around 80% of the GPU performance, this influences the decision to buy one large card over multiple smaller cards.

Mattymanx

Iray requires actual lighting in the scene. Without lights it will be very slow.

Please see this thread here - http://www.daz3d.com/forums/discussion/56788/

mjc1016

Try adding a full GI lighting solution to your 3DL scenes...and see how long it takes then.

Khory

Hi,
I’ ve read about faster rendering with Iray, but with a simple scene without any lights I see that Iray is much slower than 3Delight.
I render animations and every frame with 3delight takes let’s say 10-15 seconds where with Iray it takes not less than minutes.
I have a Nvidia 970 GTX.

Are there other settings to enable this claimed speed?
I’ ve already tried to use Iray shader without success.

I just ran a test scene with a figure, a glass bowl filled with water and a simple prop (it was what I was working on) on my 970 and it took 2.28 seconds. There is no way that scene would render as fast with 3dl. The glass and water plus the uberlighting would dramatically increase the render time. On the other hand if I were not rendering the glass and water and was satisfied with a different sort of lighting 3dl would very likely would be faster. I might not get the same quality of render however. Depending on what your goals are that may or may not matter.

A Titan X graphic card (or better, several of them), for example, accellerates rendering times by quite a bit.

Almost no one has those and I don't expect many people to be getting one any time soon. Even PA's who do hundreds of test renders a day at times are fine with something like a 970. I have yet to exceed my 4gb of vram. Even when rendering a large stonemason scenes with 2 fully dressed figures didn't go over my vram.

Iray is not necessarily faster than 3dl most of the time. It really isn't expected to be. Speed is very much driven by how you set up the scene just as it is in 3DL. Lighting plays a part and an under lit scene will render slower than a well lit one. Having the surfaces converted to Iray helps as well because there will be less to calculate.