According to : “The portals don’t change the brightness, they just tell Lightmass where to look closely for lighting. In this case with all the skylight coming in small holes they make a big difference. In a more open scene they wouldn’t be any good because the openings to the sky are large.”
sorry i am a little bit confused,i know what a portal do,but what is the name of the portal in ue4?is that box reflection capture?
If you are asking to use it, it isn’t in ue4 yet, I think that only (Unreal Engine Developer) has the portals and is teasing us.
And the next question would be when this portal will be released? 
Will this portal be released as part of UE 4.10 or as hot fix for UE 4.9?
It doesn’t seem like the portals will be ready for general release for some time, as exciting as it would be to be able to use them.
Well atleast we know that behind Epic’s doors they’re working on a solution for us, how exciting! Together with that fact that @ and Koola and are contributing to this epic discussion we should be hopeful!
Can anyone share the lightmass.ini with defaults? Somehow I lost my backup and can’t remember all the defaults.
There you go 
Screenshots attached.
This is the scene has only sky Light and following settings:
Static Lighting Level Scale : 1
Num Indirect Lighting Bounces : 100
Indirect Lighting Quality : 10
Indirect Lighting Smoothness : 1
BaseLightMass.ini
[DevOptions.ImportanceTracing]
NumHemisphereSamples=32
[DevOptions.PhotonMapping]
; 400 gives a smooth enough result without requiring a very large search
NumIrradianceCalculationPhotons=800
; Allocating most final gather samples towards importance samples gives a good result as long as there are enough first bounce photons
FinalGatherImportanceSampleFraction=.8
DirectPhotonDensity=1000
; Same as DirectPhotonDensity, since currently direct photons are only used to create irradiance photons
DirectIrradiancePhotonDensity=1000
; Need a very high indirect photon density since first bounce photons are used to guide the final gather
IndirectPhotonDensity=2000
IndirectIrradiancePhotonDensity=1500
[DevOptions.StaticLightingProductionQuality]
NumDirectPhotonsScale=10
; Decrease direct photon search distance so that we will have more accurate shadow transitions. This requires a higher density of direct photons.
DirectPhotonSearchDistanceScale=.2
; Need a lot of indirect photons since we have increased the number of first bounce photons to use for final gathering with NumImportanceSearchPhotonsScale
NumIndirectPhotonsScale=32
NumIndirectIrradiancePhotonsScale=4
Strangely, the artifacts at the edges are present only in the screenshots but not in the Editor or in Game play mode.
Thank you.
Those are not lighting artifacts. It’s antialiasing issue caused by the fact that screenshot doesn’t benefit of TXAA, as discovered.
Interesting results , build time for the scene?
I’m doing a bunch of test with the default ini.
I’m getting much better results with a low static lighting level scale (From .8 to .1) than any other settings. I’m even leaving lighting quality to 1, smoothness to 1, bounces to 10-20. I set my lightmaps res higher/uncompressed and I’m getting better results and faster!
Time to reconsider my old workflow I think. (for skylight-lit only scenes, at least).
Quick test for the indirect lighting quality alone. Lightmaps res are 1024, scale set to .4
Quality = 6 (4mins30sec build time)
Quality = 1 (1min32s build time)
Not a huge difference imo. build time is a lot higher with 6 tho.
Static lighting level scale alone now (with indirect lighting quality set to 1)
Scale = 1 (1min13s build time)
Scale .4 (1min 32s build time)
Scale .1 noticed the extruded lines on the walls receive some shadowing 
3mins19s build time tho.
In this scene, it’s clear that the best setting is the scale.
This thread is getting muddier and muddier. 
when you have a chance can you clear up some of these parameters that are being tweaked - it’s a whole lot of stabbing in the dark from what I see.
I personally really like working with a directional sunlight combined with spotlight reflectors.
My current project is a apartment with multiple rooms, and by placing a spotlight reflector at each window it allows me to control the lighting per room which for me is a huge plus.
Of course it would be easier if placing one skylight would just correctly light a whole apartment, but at the moment it doesnt work like that.
Here are some tests, settings are from message but:
Added a sunlight ( intensity 6, indirect lighting 3 )
Skylight ( intensity 0.5, indirect lighting 3 )
Post process tweaks: enable GI with a value of 3
Render time: 2:03 hours on Production
Awesome thread, lots of interesting stuff! I would also love to see those .ini settings exposed to the editor- perhaps under “advanced lighting” options to not confuse those who are just looking for the basic parameters! It’s fine tweaking the .ini file manually, but it does get quite tedious and it would make the in editor settings feel much more complete if they were added!
Oh nice! Portal Lights- sweet, can’t wait for the public implementation. great work -
I’ve just built my whole 2000+ meshes scene in 59 mins by reducing the scale to .4 (lightmaps res 1024) and leave indirect lighting quality to 1. Previous attempt with quality 6 and scale .15 took 16 hours. (with lightmaps of 256). Stunning. It looks way better now and took 1/16th of the time!
@Nicolas3D : What I have observed is, if we are using other lights along with Skylight we don’t need the high Photon Density(Direct as well as Indirect). Increasing the Photon Density, increases the build time by the factor of amount of increase from default value(400).
@ : Please correct me if I am wrong.
In your scene, you can get the same quality with the following settings with reduction of build time by around 60%:
Use default BaseLightMass.ini with only NumHemisphereSamplesScale > 64
Static Lighting Level Scale: 1
Num Indirect Lighting Bounces: 100
Indirect Lighting Quality: 10
Indirect Lighting Smoothness: 1
You can play with Indirect Light Intensity of SkyLight and Directional Light to get this quality with much faster Build time.
@: It took around 40 mins for light build. Also I have observed that these values differ substantially depending on scene. If scene has lot of closed space, as in case of Interiors, it is very difficult to get good lighting with only Skylight even with lot of changes in BaseLightMass.ini.
Thanks for the tips 
I was about to build the scene with NumHemisphereSamplesScale > 400 at Medium quality, but I notice that the build time was incredibly slow, so I guess I’ll try a lower value for that.
@: based on Rafareis reply and by some tests the scale is what gives you the soft shadow details from large/small objects and it makes quite the difference, and of course it increase the build time, not entirely sure how much since I mixed the values between tests.
With 0.15/0.25 the shadows quality is really good, but the value also depends on the scene itself and the degree of detail you want.
@: Are portals going to be included in a release soon?