Interior Iray Render Times

ebergerly

Okay, I have an interior scene I purchased, with tons of emissive ceiling lights. It looks great, but takes forever to render as the light rays bounce all over the place. We're talking at least an hour with some G3's in the scene. 

Now, when I remove the ceiling, and have the interior scene lit by just the exterior HDR it not only looks great, but the render time is just a fraction. Presumably because all of the ceiling bounces are bypassed. 

Problem solved, except when I point the camera up to where the ceiling should be of course I see the exterior HDR. 

So is there some way to have the best of both worlds? Have the ceiling visible in the render, but remove it from the bounce light calculations or whatever? 

Maybe Canvases? But I'm not sure how that would work.... 

Thanks.

Richard Haseltine

If you look in the Editor tab of Render Settings then under Optimisations you should find Maximum Path Length - currently -1. Set it to something like 8 or 9 and see how that goes (Genesis 3 requires at least 6 for the eyes to render, ignoring any reflections).

ebergerly

Wow, thanks. Actually that was one of the original setup things I did when I first installed Studio (I learned that with Blender), but it turns out it never got saved in my startup preferences. So all this time I was thinking I was running at 6 (?) or so. 

Glad you mentioned it, now I'll make sure to put it in the preferences (if I can remember how to do that...). 

Testing it on a scene now with a setting of 8. Never knew that, by the way, about needing 6 bounces for eyes...cool 

ebergerly

Well after a little testing, I found that at a setting of 8, when I disable the ceiling visibility the render is 14% complete at a little over 7 minutes.

Then when I make the ceiling visible, (but same setting of 8), even after 20 minutes the progress is at 0. And the lighting is so much nicer with the HDR lighting and no ceiling. 

So I guess I need to find a way to make the ceiling visible in renders, but non-existent in any lighting calcs so that the HDR lighting still comes thru, but it doesn't affect any bounce lighting. 

Etheral

You could look into using something like Ghost Lights to help light the indoor scene better. I've been using them and it helped immensely with my render times: https://www.daz3d.com/iray-ghost-light-kit-2

RLSprouse

Just an idea: Render the cieling separately, then composite in post.

 

ebergerly

Yeah thats kinda what I've been thinking, just trying to figure out how to make the whole process less painful. Basically I'd need two scenes, one with just the ceiling that I'd render quickly with basic lights. But I'd need to match the camera position/pose for each render in both scenes. I think thats easier than one scene where i bounce around shutting off and turning on lights for each render. But I do have Light Manager, so maybe i just convinced myself to use only one scene.....

Masterstroke

Etheral said:

You could look into using something like Ghost Lights to help light the indoor scene better. I've been using them and it helped immensely with my render times: https://www.daz3d.com/iray-ghost-light-kit-2

Is there a tutorial, how to use it?

Kevin Sanderson

There is one for the first - https://www.daz3d.com/forums/discussion/127056/ghost-lights-interior-lighting-tutorial

Seems to me there's another thread for Kit 2.

Fishtales

Make the ceiling an emissive surface and put the .jpg as the colour and set it to an intensity which gives ambient light across the whole room.