Lets make Lightmass EPIC (and understandable)

[hydeman]

Great post !
@DanielW I know it's not the right place but since we have access to a developer here, i would like to ask to you if it's possible to do something for a good glass shader.
Actually we have to trade for reflections or transparent shadowing ... or use the technique here : https://answers.unrealengine.com/que...ecularity.html
Having scene with great lighting is good but glass object who look fake kill the coolness

[maxbrown]

Just tested the Lightmass portals & hdr-sky with Koola's Lightroom project.

One big lesson for me (not a surprise to the pro's I guess): just like a photographer needs tricks (bounce cards, extra lights, moving furniture in some shots etc) to achieve stunning results, you (might) need them in Unreal as well. Due to the design of the room, dimensions / position of windows etc, some corners or parts will turn out dark. Only by using a trick (adding a light, bounce cards) a photographer in real life will be able to fix that and I think so must we in Unreal.

[DanielW]

On portal placement, heartlessphil is correct, it just needs to cover the opening. When lightmass is gathering lighting from any point in the scene, it will take extra samples in the direction of portals. This makes a huge difference on skylight quality in caves / indoors because otherwise the chance that a sample would find that tiny bright opening is very small, which translates to splotchy artifacts. Portals also affect indirect lighting from other sources but those tend to be pretty good quality due to use of photons so the difference is not noticeable.

It doesn't matter which way the portal is facing. I'm guessing vray does that as an optimization, then Lightmass would only do extra lighting samples on one side of the portal. I didn't think that was worth the extra complexity.

[DanielW]

@DanielW I know it's not the right place but since we have access to a developer here, i would like to ask to you if it's possible to do something for a good glass shader.
Actually we have to trade for reflections or transparent shadowing ... or use the technique here : https://answers.unrealengine.com/que...ecularity.html

Looks like a bug in the translucency lighting shader to me, probably easy to fix. I won't be back at work for a while though.

[Stan Brusse]

Sorry to hijack this thread, but it been days I'd like to try out this whole new workflow, unfortunately I'm unable to use swarm,
Any help would be greatly appreciated.
@DanielW, you might even have insight info on why this isn't working as expected?

https://forums.unrealengine.com/show...-on-renderfarm

Cheers
Stan

[m.orzelek]

Recently, I've been preparing my new Marketplace package, and made a lot of tests with lights, lightmass setup. Here are some of my latest results with UE 4.11. I'm happy with the quality I got in ~2min. Huge difference in light building times comparing to previous UE versions. The scene is pretty much random, but I wanted it to have a lot of geometry (those orbs objects are ~100k tris). Fun fact: Light portals don't reduce light building times for me. It takes even longer, when I used them.







Great thread btw!

[ZacD]

Portals are supposed to increase the build time, because it tells lightmass where to fire more photons. But with portals you get higher quality bakes without having to crank up the settings, so you are saving time that way.

[Wojciech]

Hey!

This is my first post on UE4 forum! This thread is fantastic, than you so much for investigating and sharing the process. I have 8 years experience of working with V-Ray and only now I can say I understand how samples work and how to optimize settings for good results fast. Now I got into UE4 and it feels like the whole process of learning I need to start again for Lightmass, so it's so great to have this thread, it's so much faster to grasp the concept of it!

Kudos to Raghu for starting the thread, DanielW for all the hard work in the implementations of new solutions and rafareis123 for the great guide with examples.

I want to share with you some of my tests too. I started my own project in UE4 and here are the results so far (I spent a day figuring out the Lightmass)

Here are my settings:

UE 4.10.2

Light Quality: Production

Static Lighting Level Scale: 0.5
Num Indirect Lighting Bounces: 20
Indirect Lighting Quality: 10
Indirect Lighting Smoothness: 1.0

No compression on Lightmaps
Packed Light and Shadow Map Texture Size: 2048

BaseLightmass.ini with default settings

for skylight texture I used Pether Guthrie HDRI





Some contact shadows are looking pretty OK - like the one from kitchen unit, but the further the light needs to travel the more splotches. Also I get quite significant differences in color between walls and ceilings. I guess now it's time to tweak BaseLightmass.ini to get rid of the splotches

[m.orzelek]

Portals are supposed to increase the build time, because it tells lightmass where to fire more photons. But with portals you get higher quality bakes without having to crank up the settings, so you are saving time that way.

Ok, my bad. I misunderstood it. I thought light portals use the same number of photons (not fire extra ones), and you just tell where you want them to focus more. Thanks

[ZacD]

Some contact shadows are looking pretty OK - like the one from kitchen unit, but the further the light needs to travel the more splotches. Also I get quite significant differences in color between walls and ceilings. I guess now it's time to tweak BaseLightmass.ini to get rid of the splotches

I'd suggest downloading 4.11 and putting in portals before messing with the .ini settings.

[heartlessphil]

The new version (4.11) is too good to pass up! Now it's easier, faster and more efficient.

[Wojciech]

I'd suggest downloading 4.11 and putting in portals before messing with the .ini settings.

I did download it, but something happened to my scene. I recreated my project in 4.11 and it just didn't work. After calculating Lightmass everything was looking wrong - I don't know yet why, I must have forgot about something, or settings are different from 4.10 and I need to adjust/change something to get correct result.

for now, further tests with 4.10:

Light Quality: Medium

Static Lighting Level Scale: 0.2
Num Indirect Lighting Bounces: 20
Indirect Lighting Quality: 10
Indirect Lighting Smoothness: 1.0

BaseLightmass.ini

NumHemisphereSamples = 256

Texture size for walls and floors: 512

Rendering Time: 2.5h







And now question, how to get rid of this artifact? It happens on most points where walls connect with ceilings. It is adjusting the texture size?



And by the way, how to get better AA quality from Highres Screenshot? A screengrab from viewport looks like that (nevermind DOF):

[Ikos]

It usually happens this to me when I use a low lightmap dimension, the only fix I found is to increase it.
For the screenshot I heard that it's a known bug, the AA doesn't work with the screenshot tool.

[heartlessphil]

I think it's more because temporal AA is a AA method that takes a couple frames to ''respond''. Look around in your scene and stop, you'll see it when the temporal AA kicks in! Apparently that doesn't work very well with a screenshot because it takes only a single frame!

But hopefully that's just a bug and it will get fixed!

[m.orzelek]

You can always export 2-4 times higher resolution and downsize it in Photoshop. It helps to get rid of most jagged edges.