Best way to preview your lightsetup for tweaking


(Splitting_Atoms) #1

Hi guys

I have a archviz scene which is in the evening. So low light. I have a bunch of spotlights, area light and lamps and stuff.

My question is, what is the best way to previz and check these lights? So I can easily adjust position, color, strength etc, while getting a real time update of what they look like.
I dont need a very realistic rendering of the materials and stuff, i just need it to set up the lights and tweak them.

At the moment, im doing this in the viewport 3D rendered view, but this is way to slow because it keeps rendering everything.

I tried the lookdev mode… but that doesnt render the strenght of the lamps. When I change strength…nothing happens.

So is there another ‘view’ that can help me with setting up my lights quickly?

im the latest build of 2.8


E-Cycles - sales coming on 4th of April and Mac 2.8 version available
(CarlG) #2

If lamp positions and such are fixed and you’re only tweaking strength and color, render out familiar groups of lights separately and simply add them together in post. That allows you to tweak strength (within reason) and color temperature per “light layer”.

If you have self emitting stuff like TVs, monitors, and even diodes, make a group node with no exposed input values where you animate on or off output which you then multiply with all the emission strengths. These should also be rendered out together as a separate layer. I.e. a monitor will have a glossy surface “Shader Add” with the emission - if the monitor is on or off it will still reflect, but when on it can drown the reflection. You don’t want to render those out together with the lights, as they will add up each time.


(Pixelfox) #3

In Lookdev mode under the Shading menu next to the view mode, there are options for “Use scene lights” and “Use scene background”. Does that help at all?

Are you using Cycles or Eevee for the final render?


(Splitting_Atoms) #4

Thank you for your replies.
I might not have been clear enough. Im lookig for a way within Blender itself to see what my lights are doing in real time. Just a quick real time preview to see where my shadows are falling, how the strength of the lights look when I change them and the colors… So i dont want to render stuff out first to see what the effects are.

I have tried the Lookdev mode, with ‘use scene lights’ and ‘use scene background’ on… and that is kinda what Im looking for… but… changing strenght of my lights…doesnt effect anything so that didnt work for me. Im using Cycles btw.

So I kinda want a real time rendering of my lights and its shadows, but I want the rest of my scene just to be simple solids or sometihng so it stays fast. (kinda like in lookdev mode).


(yogyog) #5

I think your best bet would be to put all your small objects like furniture in a separate collection which you turn off while previewing, leaving just the walls and lights, allowing you so see how your lights to light the room without having to load and render all the detailed models all the time.


(Splitting_Atoms) #6

Hmmm that might be an option… thank you

I was thinking… istn there a way to temporary override all the objects with a simple shader? Kinda like the render override that you can use for clayrenders? But then in the viewport?


(Splitting_Atoms) #7

Oh wait…the material override in the view layer tab also works in the viewport. …this might be an option!
edit: oh no wait… the override also overrides the lamps with the material. So the light is gone too :frowning:


(Pixelfox) #8

Do you have more than 100 or so lights? Eevee has a limit on the number of active lights (127?) otherwise it might be a good preview option for you.

I think there’s still like a factor of 10 difference in light intensity between Eevee and Cycles, but for your lights you can add a second material output to your node networks and have one set to Cycles and one set to Eevee if you want to have different shading for each renderer.


(Splitting_Atoms) #9

Thank you for your reply,

Let me get this straight… :
So you are saying, to temporarily switch to Eevee to preview the lights?
But there is a factor 10 light difference between Eevee and Cycles, so i need to give the lights a different material output just for Eevee, so it matches the light output in Cycles?

Is this correct? If so…how would I make that second light output? Just a extra emission node that is 10 times stronger? En plug it in when I use Eevee? Is there a way to automate this for all the lights at the same time?

Thanks!


(Pixelfox) #10

Maybe this isn’t the best way to do it, but just as an example, with the default blender scene, I can assign the following material node setup to the Lamp object:

image

Here I have two Light Output nodes in the same material, one set to be used with Eevee and one for Cycles, and then I have separate Emission nodes for each one where the Cycles strength is 10x larger than the Eevee one so that they look the same (this eventually should not be necessary once the values get normalized between the two renderes).

You can then render in either Cycles or Eevee and things should look the same lighting wise.

There may be better ways of doing this as I said.


(CarlG) #11

Huh? Light Output node works for Eevee? What can be controlled?


(Pixelfox) #12

Hmm, well, I thought it worked, but apparently not lol. Never mind.