Some IRAY questions.
Choppski
Posts: 523
1. if I used hdri files in carrara and bryce, can those hdri files be used in Iray?
2. can the files I used in uberenvironment (which were converted from hdri files) be used?
3. I assume I load them via the image option like you do a texture--i.e., the one in the environment section?
4. How do I determine where the 7light comes from (where the shadow falls)? It seems totally random as almost any light I add has no shadow options in Iray.
5. I assume I cannot use area lights, but someone taught me how to use a plane or other object and turn it into a mesh light. Fine, but can the mesh light be in the scene (with an area light it cannot) and if I want it close to the figure how do I do that without having it physically in the scene?
6. Does a mesh light or distance light cast a shadow, or is the only shadow determined by the hdri? ANd if they DO cast a shadow is there any way to control softness, etc?
7. Though I have a ton of questions about shaders in Iray, I will limit myself to one--displacement. I have seen that it can work (whereas with REALITY, it was a pain and seldom worked as well), Are there are any guidelines about using displacement? I had to up the displacement from like 6 to 75 percent to see veins that in 3DL showed up well.
THanks in advance!
(I corrected the title and instances of Iray to be spelled with an "I" instead of an "L". ~Mod)
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Comments
1, 2 & 3...
Yes, Iray can use most common formats that HDRI comes in, without the need to convert anything.
Iray come with it's own Environment which you'll find in the 'Render Settings'.
4
Shadows are 'always on' in Iray, but lights come in at a very low brightness by default.
There could be several other reasons why shadows are not visible, but that depends on your specific scene setup.
5
The Standard spotlights can have 'geometry' switched on, turning them into Area Lights, with control for the size and shape of that geometry.
If you want to make and use your own out of any mesh you can do that too. There might be a bug in Iray where the 'visible in render' option doesn't completely work, but there are ways to work round that.
6
You'll have to use the real world method for softening shadows, the bigger the light source compared to the subject, the softer the shadow.
Bigger physically. Just imagine you had a small LED flashlight in your hand. It would cast really sharp shadows compared to if you were holding a big lantern. I can't really answer your other questions because I've never used Carrara/Bryce.
When I started using Iray(and others like it,) I had a hard time using the old style area/spot lights. Once I switched to using only mesh lights (with HDRI environment,) everything got a lot easier and my renders got better.
If your renders seem too dark, you may just need to crank up the luminance on the mesh lights and possibly adjust the exposure/gamma, etc in the Tone Mapping menu. Just remember, when you look at a normal room in real life, the colors/white balance are way off, but there's a lot of image processing going on in the CPU/GPU between your ears. Now you just have to get your computer to replicate that. But that's half the fun.
You need to crank up the luminance value on ANY of the lights, as a first step...photmetric spots (etc) or mesh lights.
And do lray renders always take hours? I mean once the initial system run goes down, the memory usage is not bad, but I have one running for almost an hour and it's only 8% done. It looks cool, but this could take like 20 hours. I like it, but I don't have a computer that is used just for rendering LOL.
Also, It sort of sucks that textures and stuff seem to only come in lray. 3DL may not be as photo realistic, but so far it seems faster.
I Mentioned Reality, because that plugin for Daz Studio used mesh light and hdri and you had to change all the surfaces, and it went through iterations. It used the lux render program--I sort of though lray was just the DS4 built in version of that.
i ray is about as different from Luxrender as it is from 3DL.
I use Luxus (still do, occasionally), instead of Reality.
And, no, lighting in Iray isn't quite the same as Lux/Reality. Iray includes an 'environment' instead of Luxrender (and 3DL) grabbing a 'corner of the infinite void' and letting you define the extent of the area to work in (even Iray's 'infinite' dome isn't quite as infinite as Lux/3DL).
Let us know what type of CPU/RAM/GPUs you have, then we can estimate how long your render times should be. On my setup, most of the renders in my gallery finished in about 2-4 hours. The Amish scene, I let render overnight because it was using bloom and other blur effects.
Have you looked at your actual CPU/GPU usage? I always have windows task manager open (CNTRL+SHIFT+ESC) and it tells me what my cpu usage is. I use MSI Afterburner (there are others that do the same thing) and it tells me what my GPUs are doing. Occasionally, you may be rendering a big scene and discover that your CPU is doing all the work while your GPU(s) are sitting idle. Once the first Iray iteration shows up on screen, it should only be a minute or two until you can see it well enough to tell if the render is going to be good or not.
Sorry for being so chatty. Similar to vegans talking about veganism or crosfitters talking about crossfit, I can't stop talking about Iray once I get started.
Regarding 3DL, I've used EXR and HDR files directly in UberEnvironment.
There has not been a need to use the 'convert to TIF' script for several versions of Studio!
Without even a basic nVidia graphics card to assist, then Iray will be slow on just a CPU. Probably slower then UberEnvironment in 'Bounce' mode.
Thanks for that info about uberenvironment. Oh and I have an NVIDIA GE Force 920 M. I assume that works ok with LRAY?
Yes, except that it probably will not be used on med/large scenes due to memory limitations.
What's a medium/large scene? one figure and a small room behind him/her? or multiple figures? And does that mean that lray won't work or that the computer will shift to a different video card? Or did you mean that with 8 GB of ram, using lray, more complex scenes will shut the program down or something?
The 920M is meant for gaming not rendering, so on most of the laptops they don't put in more than 2GB of VRAM. That's about enough for a single character with basic clothes and hair, and perhaps a simple set. The practical minimum for rendering through Iray is 4GB. Check the specs for your laptop to determine how much memory it has.
What Tobor said...most laptop cards aren't going to have the 4GB ++ needed for large scenes.
With Iray, your graphics card can only use it's own 2GB of memory, it can't do anything with the 8GB main memory.
(other renderers can, this capability has not yet been added to Iray)
Iray prepares the scene and sends it to the GPU, if it fits then the GPU is used.
If it does not fit, the GPU is silently dumped and you're left with just the CPU (and it's 8GB).
SO if I was rendering a scene and it seemed to be working, but then it slowed way down (it was still working just taking forever to move up a percentage) does that mean that it was not using the nvidia card and just the other card I have? I mean it worked and the image kept getting better. But I know that the memory being used dropped a LOT after it started the iterations. This is all good to know because I won't bother with lray only textures. I thought that if my nvidia card was not right or sufficient that it wouldn't work at all.
If you want more of an idea about lighting composition and some of the technicalities (outside of the iray settings specifics) then get a book or research photography lighting techniques. Speaking as a photographer that experience has helped.