Lets make Lightmass EPIC (and understandable)

[Robbie222]

I am trying to follow Rafareis's settings. The quality of indirect is much better but I am getting some strange results which I don't know how to fix:



Before changing the .ini settings there was no issue there. Any idea what's causing this?

As you can see here it's the same mesh, but not happening everywhere:



Never came across this before.

[Ptyx]

Any idea what's causing this?

it looks like insufficient lightmap resolution for the walls / ceiling.

[Robbie222]

Can't be that. Walls have 256 and ceiling 512.

I'm pretty sure it's something in lightmass, I just can't figure which setting would affect this.

This build is done using medium quality with .4 scale , 100 bounces, 1 indirect quality and 1 smoothness.

Lightmass.ini:

NumHemisphereSamples=128
NumIrradianceCalculationPhotons=4096
IndirectPhotonDensity=6000
IndirectIrradiancePhotonDensity=3000
IndirectPhotonSearchDistance=180

I've had the same result on a previous production build with 512 hemisphere samples, 12000 and 8000 PhotonDensity.

[EoinOBroin]

Can't be that. Walls have 256 and ceiling 512.

I'm pretty sure it's something in lightmass, I just can't figure which setting would affect this.

This build is done using medium quality with .4 scale , 100 bounces, 1 indirect quality and 1 smoothness.

Lightmass.ini:

NumHemisphereSamples=128
NumIrradianceCalculationPhotons=4096
IndirectPhotonDensity=6000
IndirectIrradiancePhotonDensity=3000
IndirectPhotonSearchDistance=180

I've had the same result on a previous production build with 512 hemisphere samples, 12000 and 8000 PhotonDensity.

Have you made sure to separate your lightmap UV shells by at least one grid space? Try snapping the lightmap UV's to the grid- (if using a 256 lightmap resolution, divide 1 by 256 to get the correct grid spacing, and then snap all UV's to the closest grid space)

[rafareis123]

You have to increase your lightmap size on these walls or optmize the UV's manually. Check if your meshes are too thin. Also, don't use more than 20-30 indirect bounces. If you set it to 100, it will cause undesirable artifacts and will not bright your scene

[heartlessphil]

Rafael is right, 256 (and even 512) for your big walls is really not enough... try 1024 for each section of your wall or detach the interior face and assign a lightmap to it so it takes as much place as possible on your uv map and leave the rest of the faces on a low res lightmap. By detaching some parts, you reduce the risk of light leaking from a part to another on your mesh too!

Ex. The red face is detached because it will be the only visible part in my house. I'll assign a lightmap with a resolution of 1024x1024 to it. The rest won't be shown so I leave the default lightmap res (very low). You cannot have a better lightmap than that for your interior. A single face that occupy almost all your uv space!!! This does not cause any problem because I still have geometry behind to block light from coming in!!! It wouldn't work if I only kept the interior face tho ( at least not with some blocking bsp).

And with a script to flatten everything it does not take really longer to make it this way.

[Yanton]

There is a new update available, is someone can tell us if there is any improvement about lightmass...
Thanks for this thread, it's very helpful !

[Ptyx]

There is a new update available, is someone can tell us if there is any improvement about lightmass...
Thanks for this thread, it's very helpful !

I suppose that lightmass doesnt have to be improved for the moment (and indeed isnt part of the release notes for 4.10). One nice addition to expect will be light portals from DanielW, maybe in 4.11.

[meijervis]

I suppose that lightmass doesnt have to be improved for the moment (and indeed isnt part of the release notes for 4.10). One nice addition to expect will be light portals from DanielW, maybe in 4.11.

After that, we can throw Vray out of the window

[RI3DVIZ]

After that, we can throw Vray out of the window

I'm not convinced about that. I still see some things to overcome such as reflections and better material shaders. One of the weak links I see in a lot of the images is great materials and reflections and I've seen most of the great UE4 users work.

[Yanton]

I need your help guys, I'm confused regarding the skylight and sun light, to get better results should I use both together like in vray with the hdri dome and vray sun ?

[MSL]

Can't be that. Walls have 256 and ceiling 512.

I'm pretty sure it's something in lightmass, I just can't figure which setting would affect this.

This build is done using medium quality with .4 scale , 100 bounces, 1 indirect quality and 1 smoothness.

Lightmass.ini:

NumHemisphereSamples=128
NumIrradianceCalculationPhotons=4096
IndirectPhotonDensity=6000
IndirectIrradiancePhotonDensity=3000
IndirectPhotonSearchDistance=180

I've had the same result on a previous production build with 512 hemisphere samples, 12000 and 8000 PhotonDensity.

Were you able to solve this?
If yes, Can you let us know how you solved it?

[heartlessphil]

I need your help guys, I'm confused regarding the skylight and sun light, to get better results should I use both together like in vray with the hdri dome and vray sun ?

It depends on what you want to achieve. Start with a base skylight+hdri all the time. If it's an overcast day, leave it as is. If it's a sunny day add a directional light. Skylight is fill light, Global illumination...you need it.

[Robbie222]

Were you able to solve this?
If yes, Can you let us know how you solved it?

Not yet, I have to finish another project before going back to this. When that happens I will make a new topic so we don't overflow this one.

[Robbie222]

Has anyone figured out how to rotate the hdri used to light the scene? Is it possible to also have a visual representation of the hdri's orientation for better adjustments?