Light leak at edges inside room and irradiance volume issues

(cekuhnen) #21

good to know actually



Hmm, EEVEE… seems sort of OK-ish.

I still prefer easy setup over fast render time.


(cekuhnen) #23

can you add your file - I will render it here on mac and win



Deleted… will reproduce.
Do you want it baked or just set?


(cekuhnen) #25

why not baked so I can compare this too



Here… lightLeakER.7z (1.0 MB)

Remember, it’s a real time screen space dependent render engine where resulting image depends almost exclusively on camera frustum (with lots of cheats and approximations - low quality). Also, help yourself with AO to achieve better result (hide inaccuracies).


(Blender Foundation CERTIFIED TRAINER) #27

@Hypersomniac any progress with this bug?
I was working for a closed tunnel (squared) scene, came through the same problem. Removed HDRI world light, but light leak was still present. Roughness on pricipled, almost at zero. Problems on corners. I beveled the corners and that seemed to mitigate some of the leak.


(cekuhnen) #28



(cekuhnen) #29

Here is another test with a the light leak issue

blend file is here


(Piotr Adamowicz) #30

I have to say I don’t like the rigid grid-based system irradiance volumes use. I’d much prefer to be able to place each probe manually.


(artell) #31

@cekuhnen Increasing Exponent and decreasing Softness seems to fix it (and optionally play with the Distribution of the Cascade parameters, and increase shadow resolution)
Must be the reason why Unity shadows can’t be very soft as well.

1 Like

(artell) #32

Clement would probably reply it’s not a real bug but more an artefact of shadow maps (it’s not pure raytracing after all, we can’t expect perfect results). But finger crossed, who knows…


(Blender Foundation CERTIFIED TRAINER) #33

How is that done? (calculation). Could you share a little .gif for us, please? I´m curious about how many probes are needed for the inside of a box. Thanks.


(Piotr Adamowicz) #34

I have no idea, but you can do it in UE4.


(Binke) #35

I also pretty much have light leaks on every interior project i work with, but its very random, sometimes it magically works and sometimes not, seems to be depending on a looot of factors.



any progress on this issue?


(bluecd) #37

Iam testing 2.8 w/Eevee and have similar issues-both with irradiance and point light /see l.fixture over entrance/,
linear light neither seems to work as expected-only in the center of the wall:

Model was actually imported from SKP but I checked normals and doubles and not quite sure whats still wrong…


(Blender Foundation CERTIFIED TRAINER) #38

for now all I can say is that 90º acute angles are not working, light leaks.
Try making a bevel with 2 or 3 subdivisions on each corner/edges where you see light leak.
Another thing it seems to be affecting is light clamping.
That in addition.
I´ll be enterning to model a room in some more hours, I´ll report back how it id using these things as of current DD (daily dev version).


(Peetie) #39

To me it seems that the screen space reflections are not working (properly) under certain angles no matter what settings you use and how big/small you the lightprobe scale (Reflection Cubemap).
There is not a really solution to it as only trick around. Maybe take the shot from another angle. (AO might hide a bit, but then such an ugly AO is not what you want either and doesn’t really solve it). When using a lot of roughness (0.7+) in the materials the flaw in screen space reflections is not that obvious.

Bevel objects (At lightleaks, edges) like you are saying doesn’t seem to affect anything so far what I’ve tried.

So what I think is that there will be a solution later by devs (improving Reflection Cubemap). Meanwhile I consider only using EEVEE for scenes/shot that are suitable for it, otherwise cycles.
So far I would say;

  • Use more roughness in materials, or use cycles.
  • Take shot from other Angle
  • Is more AO an option?

Settings in Screen Space Reflections: (Does it help?)

  • Edge Fading < 0.075
  • Max Roughness > 0.5
  • Thickness > 2m+

(Eric Klein) #40

The light leaks are caused by incorrect shadow maps as has being discuss previously. Biggest issue is that Blender has poor default shadow values for interior scenes. See house scene leak fix below. Blender file HouseLightLeakFix.blend (2.5 MB)

This process should fix light leaks:

  1. Make sure that all walls have some thickness.
  2. To concentrate on fixing shadows and their problems. Disable “Screen Space Reflection” and “Free Lighting Cache”.
  3. To render nice smooth soft shadows under Sampling increase “Render Samples” to 256 or even 512.
  4. Under Shadow settings change:
    “Method” to VSM.
    Enable “High Bitdepth” and “Soft Shadows”.
    Cube Size of 512px should be okay. Unless their is small size geometry or thin walls might need to increase to 1K or 2K.
  5. Select the Light object the light type Point is working the best. Change the Shadow settings:
    “Clip Start” change to 0.1.
    “Softness” change to 0.
    “Bias” change to 0.001.
    “Exponent” can leave the default of 2.5.
    “Bleed Bias” to 0.1.
  6. Enable “Contact Shadows”. Change this settings:
    “Softness” change 5.0 except for sun light leave at 0.2.
    All other setting can be left at the default values.

Sun light are more difficult than the other types of lights to control light leaks.
Here are additional settings when using a sun light:

  1. Make sure the sun it’s pointing towards your interior.
  2. Use Cascade Size of 1024 if needed increase it to 2048.
  3. Now change the Sun properties.
    a. Sun radius size should be kept small a value 0.2m or the default setting of 0.1m is even better.
    b. If their is still light leaks increase the “Bleed Bias” in steps 0.1 until the leaks are gone.

Another important note is while learning how to setup all the Eevve settings do a Cycles render to use as a comparision.

Below is the original interior scene with it Cycles and Eevee including irradiance and reflection probe.

Eevee with this Blender file:LightLeakFix_eevee_c.blend (1.8 MB)

Below is a good shadow testing scene with Cycles and Eevee including irradiance and reflection probe.

Eevee with this Blender file:ShadowTest_eevee_c.blend (3.8 MB)

The Cycles scene was render to 2048 samples it was taking over 5 and half minutes. The Eevee scence was render in less than 3 sec without noise and all the render settings in high quality.

Edited: 1/2/2019 added sun light notes.
Edited: 3/20/2019 added change to contact shadows.


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