Most 'economic' Vray Lights to use in interior scenes?

[GD3DESIGN]

Hey yall!
I'm working on an interior with lower GI light coming in than I usually have and the render times multiplied. One kitchen renders in 10-15mins, while this one takes 1-1.5 hrs+. I know all scenes are different, and we're using different textures/bitmaps in each. But still thinking every bit helps when your're doing a lot of shots and its an ongoing design development project.
Anyway, I was wondering if the Devs have any advice if some Vray lights are more expensive than others? I seemed to notice that replacing the can lights with Spot Lights instead of IES brought the render time down a bit. I still have a mixture of Omni, Spere, Rectangle, and Spot Lights in the seen, and don't necessarily need to use one over the other. I definitely choose the light that needs the least amount of calculation. I've even turned of the sun and just getting ambient from Environment w/ default VraySky. I feel like I'm getting quicker renders this way. Have you guys seen anything to back this up? (I'm not exactly doing scientific research here....just trying some different things here and there while cranking out renders all day long)

[peerman]

You could also use portal lights in front of you windows. Maybe that helps as well? There is an excellent starter tutorial about interior rendering on the Chaosgroup website.

Best,

[GD3DESIGN]

Hey Peerman,
Thank you, appreciate the reply. Yes, I've watched all the tuts (been using Vfsu since v1.48, so not really a beginner). Just asking Chaos guys if certain types of Vray lights are easier on computation than others. In this particular scene we have can lights, led strips in the crown and on top of beams, puck lights in glass hutches and in top glass perimeter cabs, candles in pendant lights, range hood, lights under cabinets...and that's just off the top of my head. Windows are too far away from room to get good ambient light....it starts blowing out all the stainless appliances. So using rectangle lights as fill coming from each direction into the area, so those are my 'portals' in this scenario.

[delineator]

I would eliminate other variables as well - could be proxies, could be materials. You can pretty easily eliminate the material variable by using an override and see if that impacts your render times. Also, unless you have some pretty customized render settings, reset those back to default and see if the time goes up or goes down (and compare quality). Adaptive lights has been saving us quite a bit of headaches recently and it may not be on if you upgraded the project from a previous version.

[GD3DESIGN]

Hey Delineator, appreciate the tips. Like I said before, I'm not really asking for troubleshooting advice or anything like that. I'm more asking if CG has any stats on whether some Vray lights or greedier than others....or if anybody else has done any tests and has solid data on it. You know for a lot of lights, I can make either ies or spots work equally well in the same situation, or sphere vs omni in another, etc. If some lights are less noisy and render faster than others, then I would choose them for these low GI scenes to bring render times down. (Trying to find out without having spend a bunch of time running light tests myself)

I hear you on the adaptive lights. Between that and Denoiser, we're really cranking things out amazingly fast.(compared to 6yrs ago...) Like the 15min scene I spoke of in my first post...and its hard to tell with any certainty....but I think I remember with Vray 2, interiors in general where taking us anywhere from an hour and a half to 3hr+ for same resolutions. Pretty serious improvement. (once you make it through the painstaking learning curve switching from Vray 2 to 3...) Speak 'o the devil....just got an email that the vray update is available... Cheers!

[delineator]

yeah, sorry, I saw your post after I had posted my response already - I think we had assumed its was more of a basic level question. Sorry again.

I'd be interested in some hard metrics too, though it would be an interesting problem to set up a test with various light types and see what the time results would be. It might be hard to implement because they all behave so differently (spots vs ies vs very directional area lights). Anecdotally, I have stopped using IES because of what your experiencing (just long times with little benefit - plus most of the IES files I find are garbage). Same with omnis and spots and now I'm normally just using area lights as general purpose lighting and spots where specially needed. Definitely depends on project type though, we usually work on projects that are concept or SD level - if you are working with DD or CD docs and they have somethign very specific in mind, then architecturally lighting a scene with spots is probably going to be the way to go

[GD3DESIGN]

Oh sure, no problem! I'm sure it'll help somebody reading this post. (I know thats how most of us learned...long nights digging through forums...)

Funny you mention it, I was just testing some different scenarios yesterday with a can lighting...I'd been going back and forth between ies and spotlight and decided to dig up an old ies file I used to use in every project back in the day...and it was so horrible! So noisy and just seemed to take forever to render. I felt sorry for myself and what I used to go through. Man...so much trial/error...and blood, sweat and tears to get good at this stuff. Makes you grit your teeth at how easy it is for rookies to pick it up nowadays with the steady move towards 'one button' setup. But yeah, I've switched to spots over ies for can lights for the same reasons. And heck, for concept work I light renders with photoshop! ;p

Anyway, this was just one of those, 'hmmmm, I wonder..', type of posts. Of course, it could come in handy know if one light over the other could put out the same amount of illumination in less time. I reckon the CG crew are gonna be pretty busy with the v.02 release today...so might not hear anything for a while. I may getting around to running some tests some day...'when I get some downtime'... Haaaa! Never happens...

Cheers!
GD

[konstantin_chaos]

Hi guys,

The most challenging thing when it comes to lighting calculation is rendering blurry (area) shadows.
This means that if you're using Rectangular or Sphere lights the bigger the light the more sampling it requires for noise-free shadows in the rendered image.
Point lights like the Omni or the Spot will be rendered faster out of the box but once you change the Shadow Radius it'll soften the shadows and slow down rendering.
Dome and Mesh lights are specific light sources and there is nothing that I can compare them to. In any case if you just want to have rectangular light-emitting shape I would recommend using a Rectangular light source instead of a Mesh Light.

If you guys can share some image examples, I can then give you my opinion on what lighting setup would work best.

Regards,
Konstantin

[GD3DESIGN]

Hey Konstantin,
Really appreciate the explanation. That makes sense and will definitely help when making decisions on how to approach different lighting scenarios. Yes, I'd love to get advice on lighting...I'll go grab a shot now!

[GD3DESIGN]

Here's the kitchen I was working on when I made the post. I should note that I just checked and I'd gotten the render time down to 25 minutes that day. So again, not complaining about the time, just like to expand knowledge about wise Vray LIght usage. Also, this is design development...not trying to put out a perfect render....but want the time we spend rendering to be as efficient as possible. We'll probably render this same kitchen with multiple views 3-5 times a week for the next month until the homeowner signs off on it. So, almost like rendering animation....shaving off a few minutes per render can add up.

Anyway, would love to hear what you have to say. Thanks for your time!

GD

Lights used in this scene:
Canlights - Spot lights and ies (both lights in each can light...after some tests, I liked the way they mixed together)
led strip in crown - Rectangle
Fill lights coming from opening where camera is, back hall in center of shot, and hall opening to right of fridge - Rectangle lights (size of opening)
lights in cabinets - Spots (pretty sure I'd just changed the tops from omni to spot lights....)
range hood - Spots
I had some omni lights in the pendants, but I turned them off here because I didn't think they were bringing much to the picture
I did turn Sunlight back on in this shot, full power
Environment at .5 or .25 with VraySky.... (turned down because it was really blowing out the stainless steel refrigerator and lowering the burn value past .5 was washing things out too much.