Were is this lightbleed coming from

Hey guys, im testing out Eevee in 2.8 for a new project. Its a very simple setup

A small house on a plane. THe plane and house are same material, both just a BDSF shader with the color changed. I put an area lamp inside the house…to get that feel of a lightbulb that is turned on. Im getting that lightfalloff going out the window… which is good

But Im also see a lot of lightbleed around the house itself…Which I dont want. ANd I dont understand why this is… the underground is overlapping the house so there is no gap for the light

What am I missing?

Hi :slight_smile:

You are pointing out the difference between raytracing renderer (cycles, for example) and non raytracing ones (OpenGL, and by the way, Eevee). Light path is an approximation, but real light beams are not computed, that’s why this kind of light going through a surface can appear…

In your case, fitting the exponent seems to be a solution :

See you ++ :slight_smile:
Tricotou

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Hi thanks for you anwer :slight_smile:

I have tried your settings…but its still showing that bleed, no matter how high i set the ‘exponent’ setting

So im not sure im doing it right…

As a follow up question… My client is asking me to create something like this…

Would this be something that is faster to make/render in Eevee? Or would cycles be fine for this too? (Im mostly worried about speed of rendering) I thought this would be Eevee hands down…but if I run into problems (like this one with the light bleeding). i might be better off doing this in Cycles, which is more familiar to me…

There are lot of different scenes in the video, do you think about a specific timecode ?

Its mostly the style that they want… Something like the style in timecode 00:36
So a diffuse kinda setting with 1 color, some light animation, simple models… and some lights that turn on and off…

So i figured… Eevee isnt the best at photo realism…so as long as its not photorealism… It will be a LOT faster to create and render this type of simpel cartoony style in Eevee…

Was I wrong?

Ok,

I’m not really familiar with eevee, but if I had to reproduce this style, I would definitly use Cycles !

And for the rendering time… I don’t know how much in a hury you are… I have the chance to use Blender daily as a pro so I have a big computation power, I’m not used anymore into having a look on render time :joy:

But for this kind of “light” scene, with low poly modeling, you could manage to have a very efficient (and quick) result with few samples, using the denoiser :slight_smile:
(Denoiser can be bad when you have a lot of very sharp little details, but for low polys with smooth lighting it’s perfect)

Thank you for your quick answers :slight_smile:

What would be your arguments for using Cycles for this? Because of the lighting that is used? Or just because you are more familiar with Cycles? (like me?)

And yeah these are not the most complicated scenes…but i for an animation that runs at 50fps… its a lot of frames to render so i figured that Eevee would be better for this…

You share the .blend file, no matter how simple it is.
So other users can better analyze the situation and be able to see all your configuration, even see if the problem may be due to a specific hardware/driver

Of course, you are right

here it is

Because of how easy lighting is for having a kind result
Here is a quick gif I just made to illustrate my point :


And result :

Ray casting renderer is amazing for light going through window like this, because the soften light computed by rays is very realistic
Here just a plane with emissive shader, diffuse shaders on floor and window, and the render is very quickly “pleasing” for eyes I think.
It means after some fitting of your params you can very quickly manage to have nice render for this kind of lowpoly and light going trhough window :slight_smile:

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This is a great way to make your point haha… I does look great without a lot of effort. I didnt know this kind of lighting would be more difficult for Eevee…But apperntly it is because its not ray traced…

So basically, my best choice would be to go for Cycles, and optimize the scene as much as I can to keep down render times…

Thank you so much for your input btw. Appreciate it

Splitting_Atoms,

That issue is related with Eevee having bad defaults for light leaks. See my post on this issue Light Leaks.

Here is your scene without light leaks and nice soft shadows.

See blend file with out leaks blend_test_no_leaks.blend (2.5 MB).

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You see if this is a bit better for you:
blend_test_mod.blend (2.5 MB)

You see Shadows settings in Render tab (Soft Shadows quality depends on Sampling settings). You see the interior Area lamp settings (Power seems very strong anyway). Probably you have to configure the rest of the lamps better also.
You edit the first message and you share there .blend file there, to make it easier for other users to discover.
By the way, there is currently some documentation for Eevee:
https://docs.blender.org/manual/en/dev/render/eevee/index.html

Edit:
I was writing while @eklein had posted his message. Better pay attention to what he has explained.

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Thanks guys, I used the guide that Eklein made, and it works like a charm. no more lightbleeding!

Problem solved, thanks again!