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General Lighting Questions for the Pro's

Hi everyone, I had a couple questions about lighting and was hoping some of you lighting pro’s could help me out, as well as anyone else looking for tips.

  1. Is anyone getting good results without changing baselightmass.ini? or is the current accepted standard that it needs tweaking?

  2. What is the best way to brighten the entire scene if its looking too dark? The exposure bias seems to brighten it up nicely, but then you’re dealing with a lot of bloom.

  3. Are spotlights with low intensity and no inverse square falloff the best way to go for the bounce cards?

  4. What settings do you guys use when tweaking your lighting? Obviously ‘production’ quality with 100 bounces would cause too long of build times when you’re tweaking, but would dropping it down to a lower setting give you the same results?

Thanks for taking the time to read and help me out.

From what I understand do not tweak the .ini all parameters that you need are available in the interface.
You can turn off the bloom entirely - I believe it’s in a post process volume or world setting?
100 bounces is overkill since after about 8 it’s diminishing returns.

Thanks for the reply RI3DVIZ! I thought I read the you could access all the baselightmass parameters from within the engine as well, that’s why I was curious what people were using now.

I’ll have to try turning off bloom, it’s been while since I was messing with the exposure bias.

I assumed everyone used 100 bounces, thanks for clarifying that. That should help with the build times!

If you can afford the time go more bounces but in reality you don’t need a hundred imo.

Epic stated that it doesn’t affect build time really. For me what seems to affect build time the most is the resolution of my lightmaps :-S

I usually go with 10 bounces. It’s not much of a difference from like 4 though.

Curious about your card reflector settings also.

Also I have another question maybe someone here can help. Back in like 4.2 version there was a post from someone explaining how to setup the engine in order to use the full power of the processor when building the lighting. ( instead of being able to play and do whatever else and have 1 h build time you could of change it so when it’s building you can’t really do anything else cause of the fps but instead get less than half build time). I can’t find that post anymore.

I’d like to know this as well, maybe turning viewport realtime ‘‘off’’ before starting building the lighting? That’s what I do anyway.

Not sure if this was directed at me but I’m using the same settings as the Berlin Flat and Koola’s demos, a static mesh plane with a simple white constant in the diffuse. What intensity are you guys using on the spots for the bounce cards?

One more thing I was curious about, the Sky Light, are you folks using them?. I noticed they don’t use one in the Berlin Flat scene, but I think every other demo I’ve seen has used one.

Well out of the box it’s good and getting better but still work to be done to make vis quality renders. My guess though is Epic probably never even considered that UE4 could be used for vis but it seems to be a market that’s taking off on its own so I’m OK with working with in the box and wait to see if the tech catches up. Experience wise starting with 4.0 the results were disappointing but in 4.9 things are getting really close to what I would consider vis quality except for a few small details so here’s hopping that a 3rd requirement as to setting up a base project will included vis one day.

Photoshop is your friend. The ideal would be X number of exposure levels and then combined them in Photoshop that has the tools to fully control the lighting levels from dark to light. For vis though it would be nice if UE4 could render out in passes.

Personally I’m not big on the idea of bounce cards. A kicker point light works best for me for those hard to get into places.

The thing about vis it’s all about getting the best render and not about how much time it should take to get it. If it takes 3 days to render out a perfect 4K image then that’s how long it takes. As to how many bounces think of the emitter as a bouncing super ball that is restricted to X number of bounces. If you bounce the ball at the beginning of a hallway set to 10 bounces it might only make it halfway down the hall. Set to 100 it could make it all the way down with out the need for a kicker.

Thanks for the answers FrankieV. I am still having a heck of a time getting anything decent without washing everything out. I must be missing something but I’m at a loss. I’ve followed all the advice here, and even copies other projects exactly but can’t get good results.

I’ve uploaded an album on imgur. Excuse the quality, I threw it together quickly and most of it is right from Revit model-wise. Does anyone see anything that jumps out at them? I feel like I’m so close yet so far away.

Here’s the album: http://imgur.com/a/xbMi8

Looks to me that you’re getting color bleed off your floor material onto all your walls, adjust your post processing saturation - I think that’s where it is. There’s a way to get rid of that, I’m new too so I forget where it is. Second where you have windows in the space it doesn’t look too bad. What about adding down lights in the other areas? Also, you can adjust the exposure - “Auto exposure” minimum and maximum in the post processing volume. It says it’s the same as tweaking lights.

Here’s a good quick tutorial as well: https://forums.unrealengine.com/showthread.php?82045-Nice-tutorial-for-arch-viz-lighting-by-Alan-Noon

Read this too:

https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/Lightmass/index.html

I see there’s a desaturation node too. I always try and desaturate my materials first then the whole scene if needed.

Hey RI3DVIZ, thanks for the reply. I’ve tried playing with the exposure, but when I use that with a high ambient light intensity, it gets to be too much around the windows, even with bloom off. Would de-saturating the materials help brighten the room?

I’ve also tried following Alan Moon’s tutorial, but can’t get the same results in this scene.

Am I wrong in thinking I’d be able to get into those dark areas without additional lighting? Maybe I’m taking the wrong approach.

The way I understand the min max settings is they work the same as adjusting the lights. So, have you tried reducing your ambient/bounced light intensity and adjusting the min max value? I think they work in combo with each other.

From what I have seen with this engine it is not the same as say Vray or an unbiased render engine like Maxwell. Every scene I have seen with good lighting has lots of windows/portals. I haven’t tried a scene like yours but you might try just adding some point lights low intensity for fill back in those dark spaces.

Desaturating might help a touch but not much.

I was under the understanding that the auto exposure replicated the eye adapting to the light and therefore setting the values to be equal it would ‘turn off’ eye adaption. I will try it out when I get home.

I just saw Raghu’s post about his interior/exterior scene and he mentioned he only uses a directional light and a skylight, looks like I need to go back to the drawing board. :stuck_out_tongue:

I believe if you ctrl alt over the parameters on the min max values it tells you what they do.

Max value screen grab.max.jpg

Raghu’s house has lots of windows, probably why he can light it that way.

Hay that’s not bad but it does suffer from a rather common problem of far to much AO. Knock it down so you just see a hint and that would be more realistic.

Can you post an image of your material BP. Unreal 4 make use of what would be considered advance rendering engine that makes use of real world values so what would be more important than the lights and number of bounces would be the make up of the material. To have an accurate PBR type material you “must” have a base color, specular, roughness which = gloss, and a normal map. The bounce needs this information so it know how much energy it needs to produce when it bounces off of it and coming off a painted wall is not the same as coming off a surface with a hi reflectivity index like a mirror.

Hey guys, so after getting home and playing around with it I have a much better looking scene. It was a combination on my exposure bias, exposure min/max, ambient lighting intensities, and my AO. I guess it goes to show that just because a setting worked for one person it doesn’t work for everyone. I appreciate the help and patience, I’m going from knowing nothing about ArchViz to trying to learn 3ds max, Substance Designer, and UE4 all at once, it can be a bit overwhelming and you look over stupid things.

FrankieV, like I said I’ve been using substance designer to make my materials, but what is the deciding factor that tell how much light to bounce off?

As for my bounce cards material, it’s just a simple 3 constant on white.

There is still a lot to fix, but this model was made and unwrapped pretty poorly.

Direct Link: http://i.imgur.com/ULllNZb.png

Congrats if you can handle learning max and unreal and substance at the same time! hehe. Keep it up!

Well how much energy a surface will reflect is based on it’s reflective index and all objects have some form of reflectivity even though their index is super low. As examples a flash light will reflect more light than is imputed than say a brick which has a much lower index due to the uneven nature of the it’s surface so it’s a mixing of the 4 must have textures that creates a procedurally correct material. With out some level from all 4 there really is no way for a physics based rendering engine to accurately reproduce a real world result if your trying to produce a photo realistic render.

But for paint as an example keeping in mind that roughness is the same thing as glossiness I use

3 constant for the base color. Base color I usually use off white and link a larp to an off set color like blue. (splits the hue between night and day color proofing)
Specular with a low white gradient
Roughness using a texture I made in photoshop’s cloud render. I uses this for imperfect paint jobs that look a bit blotchy but a single constant will do the job for perfect paint.
I use a couple of different normal maps depending on the type of surface. A typical apartment celling will have a bumpy surface so high input for bumpy and low next to now for flat white painted walls.

You could decrease the input of roughness and the material will become more reflective but if you done decrease the input of the normal map then the result will be a reflective bumpy surface so to get it perfect takes a balance of all 4.

Interesting though PBR or procedural materials is not unique to UE4 so information as to physical based material construction is the same with all physics/photometric based rendering engine .

As for lighting techniques as a premier I found this to be an excellent lecture.

Did the entire video with out using GI or directly light and some of his techniques works well in UE4.

Now an opinion. I’ve tried substance and they are excellent for layered materials but found not so hot on large surfaces and have found making my own from scratch produces better results.