Lets make Lightmass EPIC (and understandable)

[MSL]

Some comparisons

Raghu's original. Settings were StaticLightingLevelScale .1, IndirectLightingQuality 10, IndirectLightingSmoothness .75, no compression.
[ATTACH=CONFIG]64441[/ATTACH]

Improved solver quality + portals setup. Settings are StaticLightingLevelScale .2, IndirectLightingQuality 10, no compression, all others defaults. I probably should have turned down the smoothing a bit, notice how where the walls meet doesn't look quite right. Also, the exposure is different than Raghu's.
[ATTACH=CONFIG]64445[/ATTACH]

Raghu's original. Settings were StaticLightingLevelScale .1, IndirectLightingQuality 10, IndirectLightingSmoothness .75, no compression.
[ATTACH=CONFIG]64446[/ATTACH]

Improved solver quality + portals setup. Settings are StaticLightingLevelScale .2, IndirectLightingQuality 10, no compression, all others defaults.
[ATTACH=CONFIG]64447[/ATTACH]

@DanielW :
Is there any way that, you can push this into upcoming releases may be in experimental section?
If so we will be able to do more experimentation and tests which may help to improve it further.

[Raghu]

Few more questions - @DanielW

It might feel unfair, but I have few more questions to ask (already experimented with some values/ earlier solutions provided) and as 4.11 is yet to be released, If possible kindly provide us the solution to the - "Light leaks due to spot/point/direct lights in static mode" as I can safely assume that you have already figured it out.

Here are some more experiments (these are obsolete now, as Daniel has already implemented the changes in Engine itself but I have already done these yesterday, so posting the findings only)

DanielW's suggested solution for light leaks Post #95

Lightmass settings in engine -



Renders (Results) -



Rafaries123's solution to light leaks

Lightmass settings in engine



Renders (Results) -




Conclusion - I am not able to solve Light leaks. May be I am missing something. Need foolproof solution now.


@ Rafaries123 post #86 - I am not able to find - "PhotonSearchRadius" value anywhere. I wonder where this value is?


@ DanielW - As now I am trying to learn Lightmass and Photon mapping deeply, It's kind of a mystery to me, what these settings change (in BaseLightmass.ini or may be in some other config files) when we manipulate them in editor -

Static Lighting Level scale from 1 to .1

Indirect Lighting quality from 1 to 10

Indirect Lighting Smoothness from 1 to .25

Link to download Light Test sample file - https://www.dropbox.com/s/ntl2o3mps5...tmass.rar?dl=0

File Snapshots -





As usual, looking forward for the reply .

[Enter Reality]

I strongly suggest you to apply those changes in Rafaeris workflow:

Static Lighting Level scale: between 0.15 and 0.4 ( 0.4 works 80% of the time as well as 0.15 )

Light bounces: 100

Indirect Lighting Smoothness: 0.75 / 1 ( I usually use 1 )

Set lighting to Production

As soon as possible I will test your scene, but on a couple of test I did ( with both skylight or bounce cards ) the leaks are gone

[rafareis123]

Unfortunately I'm not having time to finish the article in the next few days, but I will.
So this is my final settings.


Preset Quality = MEDIUM

EDITOR
Static Lighting Level=0.15
Num Indirect Lighting=20
Indirect Lighting Quality=10
Indirect Lighting Smoothness=1.2

BaseLightmass.ini
NumHemisphereSamples=256
NumIrradianceCalculationPhotons=4096
DirectIrradiancePhotonDensity=1024
IndirectPhotonDensity=20000
IndirectIrradiancePhotonDensity=16000
IndirectPhotonSearchDistance=180

[MSL]

Unfortunately I'm not having time to finish the article in the next few days, but I will.
So this is my final settings.

Preset Quality = MEDIUM

EDITOR
Static Lighting Level=0.15
Num Indirect Lighting=20
Indirect Lighting Quality=10
Indirect Lighting Smoothness=1.2

BaseLightmass.ini
NumHemisphereSamples=256
NumIrradianceCalculationPhotons=4096
DirectIrradiancePhotonDensity=1024
IndirectPhotonDensity=20000
IndirectIrradiancePhotonDensity=16000
IndirectPhotonSearchDistance=180

@Rafareis123 :
Amazing!!
Looks like we can solve majority of lighting issues by tweaking the values of currently available settings in the engine. Probably, we need to follow the workflow you guys use to achieve this quality.
Looking forward to your article. Please provide the complete workflow and checklist you follow to solve the lighting issues that may crop up.

[RI3DVIZ]

When I turn static lighting down to that value my computer freezes. So, do I need more ram or a better cpu? I have a quad i5 16mb RAM.

[ikifenix]

When I turn static lighting down to that value my computer freezes. So, do I need more ram or a better cpu? I have a quad i5 16mb RAM.

You need more RAM, and computer doesn't really freeze, if you give a lot time it will come back to life, looks like that because is writing a lot stuff in the hard disk as virtual memory and is very slow.

[RI3DVIZ]

You need more RAM, and computer doesn't really freeze, if you give a lot time it will come back to life, looks like that because is writing a lot stuff in the hard disk as virtual memory and is very slow.

Okay thanks.

[heartlessphil]

It's weird I have 16gb of ram and never got any problem with any lightmass settings or scene!

[serriffe]

When I turn static lighting down to that value my computer freezes. So, do I need more ram or a better cpu? I have a quad i5 16mb RAM.

yes, you need more ram, I just had this problem. I was observing the MS Task Manager while it was building the lightmass and it took up the same amount of memory as my project. So if your project size in Memory is 2 gigs- I think lightmass will take up the same amount of memory as well. btw I'm using Swarm Network rendering.

[DanielW]

Is there a workaround for point C) at the moment?

If possible kindly provide us the solution to the - "Light leaks due to spot/point/direct lights in static mode" as I can safely assume that you have already figured it out.

The light leaks that occur with a stationary spot light come from application of the .1 StaticLightingLevelScale to photon settings. In particular, a ton more photons are emitted at StaticLightingLevelScale .1 and the search distance is decreased. This is supposed to increase the quality of the photon representation, but for some reason (I have not been able to determine) it results in a huge amount of variance / noise / splotchiness. This causes the phantom lights 'light leaks' in your images.

I simply disabled application of StaticLightingLevelScale to the photon settings in code. You can probably achieve the same workaround by increasing IndirectPhotonSearchDistance by 10x if you use StaticLightingLevelScale .1, effectively canceling out the scale. I have not tested this myself though.

@ DanielW - As now I am trying to learn Lightmass and Photon mapping deeply, It's kind of a mystery to me, what these settings change (in BaseLightmass.ini or may be in some other config files) when we manipulate them in editor -

Static Lighting Level scale from 1 to .1

Indirect Lighting quality from 1 to 10

Indirect Lighting Smoothness from 1 to .25

StaticLightingLevelScale - this scales the density of every computation lightmass makes. It has two big noticeable impacts - for final gathering (which computes first bounce GI from lights + sky light direct) it increases the density of light gathers. It won't actually increase the _quality_ of light gathers, just how far apart they are on a surface. This improves contact shadows but explodes your build time. It also increases the density of photons emitted, this is what I disabled in my latest change to work around the phantom lights.

IndirectLightingQuality - this mostly increases the number of rays traced at each final gather, also known as NumHemisphereSamples in the ini. A value of 10 means 10x more rays and therefore 10x longer build time. You can think of more rays as a higher resolution image being resolved, so it improves the quality of light gathers.

IndirectLightingSmoothness - we filter between light gathers a bit to hide the last little bit of noise. The default amount of smoothing is quite high, so it can be useful to lower this to get more detailed shadows. Note that smaller values for StaticLightingLevelScale also decrease smoothness, so with a StaticLightingLevelScale of .1 you probably don't need to reduce smoothing anymore. IndirectLightingSmoothness doesn't affect build time.

[unvermelih]

i did some tests. there is no skylight in this test. used 2 spot lights front of the windows with projection planes. results:





2 hours render time.

win64 app download: http://we.tl/URPTjvhIWq

[tupikp]

Thanks for the explanation on those basic lightmass settings Daniel! Appreciate it a lot

[DebkowskiSKYLINE]

I've made a test scene and played a little bit with skylight. I am really happy with the result.
Lightmass settings I used:
static lighting level scale 0.6
bounces 100
indirect lighting quality 10
smothness 0.8

you can watch the animation in this thread: https://forums.unrealengine.com/show...terior-Archviz

[amir.pourshafi]

wow its better than vray,cant wait for your article