Lighting: Luxrender vs Iray
Nyghtfall3D
Posts: 813
I posted this on another forum I frequent, and decided to share it here, as well. The person I was responding to was not aware that Reality can create mesh lights.
Turning meshes into lights has been one of Reality's principle features, and main selling points, since its debut, in 2010. However, unlike Iray, converted meshes are also conveniently assigned to Light groups that can be independently tweaked in Lux while rendering.
With Iray, you can tweak the Emission shader for any mesh you've applied it to while setting up your scene, but once you start rendering, they're locked in because Iray's progress window blocks DS, and the only lighting attribute you can adjust while rendering is Tonemapping. Thankfully, DS's Iray Draw Style helps make up for that limitation by letting you use the Viewport to preview your scene with Iray before starting the render process. Incidentally, the Iray Draw Stye also offers a slight advantage over Lux by providing real-time feedback for any lighting adjustments you make prior to rendering.
So, the question for artists deciding which engine to use is, "Would you prefer a real-time preview of your scene before rendering, or would you rather be able to make adjustments even... say... 5 hours into a render, without having to start over?"
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Comments
it's more of a LuxRender vs Iray comparison but it's a key feature. The ability for me to say "if only I could add more luminance from this particular light and it would calculate the effect to the items in the scene without oversaturating like post work would do and perform those calcuations while I'm rendering" and then saying "oh wait, I can" and sliding a parameter dial to do it.
How nuts is that?
Excellent point. I've edited the thread title accordingly.
That's a key advantage of Lux that I had forgotten how much I missed until I started using it again. I recently took Pret-a-3D's new V7 automatic preset for a spin, and suddenly remembered how great it felt being able to tweak each mesh light during the render.
I've used Luxrender more or less since Reality first came out and pretty much exclusively until a few months ago when I decided to try Iray (I won't go into why here). The feature of real-time interactive light groups in Luxrender is of course very handy and I used it with every render, but I did not tend to change the light groups once the render really got going. In other words I could sort my lighting balance in a short time and not feel the need to improve it after that.
That being the case (for me at least) this Luxrender feature is not a great advantage over the ability to preview changes in my scene in real-time using the viewport Iray drawstyle, and this mode has great advantages over Luxrender because I can change anything during this preview, not just light balances. Add to this the fact I now have a fairly powerful graphics card (980Ti 6G)—and the size of the scenes I generally do has not hit the memory limit so far—it means that there is no "5 hours into the render" any more. It's more like 30 minutes at the long end, and if I feel I've messed up the lighting balance during that it's not a big deal to start again.
Well, In Luxrender you do not really change the light intensities during rendering :-)
What Lux does, is very simple. It renders each light group individually (in the background) and combines them to one image - the image you see on the screen. Now, if you change a "light intensity", you do nothing else than change the opiacity of that light group image. This is very comparable to the Photoshop method where you render each light individually, load the images as layers in PS and change their intensities.
While this function in Luxrender is very handy, it is absolutely no vodoo. And I would really love to seee this feature in Iray too!
Seeing as how my Iray renders rarely take 5 hours, not such a big selling point for me.
And since I can render to canvasses and effectively create a seperate canvas for every single light source and adjust them at will when compositing, I essentially have exactly the same control in much less time and with more options.
So, for me, Iray wins, hands down. And that's without going into the reasons why I find Reality to be challenging, at best. And I do mean Reality, not LuxRender... because LuxRender's challenges are a whole different story.
I also dont understand why people think their first render must be at the final resolution. If you don't like using Viewport (slowish and not completely accurate), you can always render at a smaller resolution. That will still be adequate for checking lighting.
Still, we always seem to devolve into a this vs that discussion as if it was a zero sum game. If you prefer 3Delight, fine. If you prefer Reality, fine. If you prefer Iray, fine. Blender, Octane, etc. It just seems like folks too often somehow have self-image tied to all their choices
Quite right. I'm sorry if I upset anyone. That was not my intent.
Every engine has strengths and weaknesses. What's important is that whatever we choose gets the job done for us.
I liked reality, but it always rendered geografts with a huge nasty black seem, so I switched to iray. Iray seems to be a whole lot faster, it takes a few hours to render in iray, while it took sometimes a day or more in reality to get a comparable result. Was just easier to use iray in the long run. Like Hiro Protagonist, I use the iray drawstyle to finetune right before render. It takes about 2 minutes or more to start up, but once that is done, any change made to the scene renders in a few seconds after that. I only have a gtx 960 though, and a first gen i5 processor.
the i5 is the bottleneck to Lux, and if Iray is all through your GPU your CPU is not getting used.
I had to remap the Iray drawstyle in Studio, if I pressed it by accident it would just grind everything to a halt until while it made it's calculations.
I also found if I collect my textures for Lux it starts up much faster than if I didn't.
I'm working on a new project and just discovered an alternate use for Iray. I'm using the Iray Draw Style as a guide to set up my scene, before I send it to Reality for further editing. Now I can enjoy the benefits of both engines. :)
it's not voodoo, either is network rendering. Does Iray feature that?
Nothing is as easy to do network rendering as Luxrender is...
I also have gone back to using lux and iray lately. Thanks to your tip I let iray render until I am satisfied which can take longer at times. However still faster then lux overall. With reality I will only render what will work with 1 light in the acc none boost mode. I find if you add more then 1 light with Reality/ lux there is nose patterns on the skin. I read on the forums that there are workarounds like needing to angle the lights certain ways and such. Since I have both engines its not a big concern. Lately the commish project I am working on is all iray.
Great idea!
Don't get me wrong about Reality/Lux, I will continue to support it and I will pay for any upgrades that are substantial enough for the developer to warrant charging for. I also don't believe there are "app wars" over renderers—I've seen zero evidence for that, and I'm certain that you did not open this thread to start one.
Ok, Lux may shine in lighting functions, but Iray has at least one massive advantage over it: Speed.
I ran my project through both engines. This is what it looked like after 5 minutes in each.
I'm glad we have more options now. I'm finishing this with Iray. ;)
If you havne't already, shut off the noise filter in Iray, it only slows you down. My renders go twice as fast with the filter off
You can do a canvas per light source?? Oooo. Hadn't noticed that. (Playing a lot with Iray canvasses now that I have Photoshop)
Thanks. It's already off.