Interior Lighting with Lightmass

[diecou]

Hi Guys,

I'm a newbie in UDK and I'm trying to make an Arch Viz from a building I've already done in 3DS. But, no matter what I do, I can't get any decent indirect lighting on interiors. As you may notice per the image below, the indirect lighting is almost gone. I've checked several posts on this forums, and I've seen some of you who achieved great results. I tried to replicate some of the Lightmass configurations I've seen with no luck. Lowering Static Lighting Level Scale, seems to help a bit, but I've also seen interiors with that parameter set as default (on 1.000) with decent lighting.

Would any of you point me on the right direction? I'm using the mid day template on UDK June 2011, so I have a Dominant Direct Light, GI turned on, and Default settings. I tried different settings with no luck, so I prefer to attach and image with the default settings rather than other ones who doesn't do the trick and might generate some confusion. All meshes have their respective UV layout on channel 2 (created on 3DS). Don't stop looking at the lack of materials right now, and any other stuff as I want to focus myself on getting a decent lighting prior putting more effort onto materials and UV layout.

I've been struggling for weeks, so any help would be greatly appreciated.



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[darthviper107]

If your meshes aren't the same scale as other people's then the setting wouldn't be the same for you.

In addition to that, UDK has HDR rendering, basically it adjusts exposure based on where you are, so when you look into an interior while you're outside it's going to look dark because the sun is so bright, likewise if you're inside and you look out then outside will look too bright.

[diecou]

Thanks for answering!

I used the following scale: 1 Unreal Unit = 1 3DS Unit = 2cm. These walls are all 3mts high, therefore, 150 Unreal units high. I'll try resizing the meshes to see if I can solve it that way.

Believe me, when I go into the building, it looks as dark as you see it from this picture. I provided this one so you know better my problem, otherwise I'd have to attach a completely dark picture (and I mean 99% black).

[Racer X]

In 3ds max you need to inscrease the number of light bounces so the photons are pushed further into the model. Plus take the time to ckeck out sIBL, it does an amasing job are using HRDI and 3DS Max´s sun light for this kind of work. U can also add a square light in front of the building (gentle blend) to help out, no one will know the difference. It´s all about making the eye believing

[diecou]

I think I'm not following. How would changing light settings in 3DS have an impact on my meshes on UDK. I have no problem at all to create a proper renderings on 3DS, they come out pretty well, but I don't want to bake the lighting onto the texture but let Lightmass do that job for me. (btw, sIBL seems to be a good tool but it appears it has support for C4D, not 3DS).

I tried resizing de meshes on a 2.5x scale factor, and it seems to help. I think I should play a little more with the ExponentialHeightFog on that case. But I can't help but thinking that this shouldn't be the way (just resizing the meshes and the player) and I'm missing something. I have read nowhere about this as a solution, and even when it seems to help me (and I'll be using that approach unless someone comes up with a better suggestion) I believe that the other works I've seen haven't been created this way (of course, that's just me guessing).



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[Racer X]

Sorry I didn´t read all the way through. THought you couldn´t get want you needed in max and tried UDK.....my bad

[diecou]

Almost correct! In max I get all that I need. I learned to create some good renderings and videos. I want to use UDK to create a walkthrough, which I obviously can't do in max. It's really frustrating to be stuck just at the beginning :s

[Racer X]

What is your main renderer? I use Vray, but on animations, walkthroughs it takes forever and a couple of days to get it done..

[diecou]

I use Mental Ray and VRay too. If you use 3DS give SolidRocks a chance. You can speed up your renderings (or take the same time, but with more quality) and surely that'd help you on your videos. And if you have no object or lights movement you can re use the indirect light. But of course, there is no workaround for reflective and transparent materials which will use much of your rendering time.

[Racer X]

aLso use SolidRocks.. VRay RT is a little faster but no real time navigation speed yet that would be just great!

[seenooh]

There are two things you can play with:

1- Set the Indirect Illumination Occlusion Factor parameter to something like 0.5.

2- Brighten up the Environment Color parameter.

Both are found under the Lightmass category in World Properties.

[box-0]

In addition to that, UDK has HDR rendering, basically it adjusts exposure based on where you are, so when you look into an interior while you're outside it's going to look dark because the sun is so bright, likewise if you're inside and you look out then outside will look too bright.

HDR rendering doesnt mean it includes eye adaptation wich is not included by default in the UDK, if you go in a dark place it will stay dark.
Anyway you can try adding a skylight in the scene and see if it helps, it should brighten the too dark areas of the scene, playing with the indirect diffuse boost parameter could help to increase the bounced light too.
if you need further assistence you could share the map and i can arrange a setup for it.
Check it out and let me know

[diecou]

box-0: In fact, I've tried the other day with skylight as you suggest, and that seemed to help. The problem is that as those areas were almost dark, I don't think I'll have soft shadows for the furniture this way. But I haven't got there yet (I have to study for an exam next week, so no UDK for me for a few days) so I'll check that out next week. And of course, if you could arrange a setup if needed I'd deeply appreciate it!

seenooh: I played with those parameters too (and others on World Properties and directional light too) and the problem remains. That's why I think I may be missing something obvious.

[Tom Shannon]

From your screenshots, I can see you're using the default material. It doesn't really seem to bounce light too much as it's actually a fairly dark texture. Try making everyting pure white. Also, if you're trying to get light into a space, you should have your camera inside that space rather than outside looking in. To light an interior accurately, you need to overexpose the image either though brighter lights or through post processing (Or a combo). That makes the exterior blow out big-time, so trying to 'balance' the exterior and interior lighting is difficult.
To allow more light to get into your structure, 1) Turn off ambient occlusion inthe Lightmass properties in World Properties, 2)Increase the Diffuse Boost in the Lightmass settings. Increasing the number of bounces can helpa little but not muc after 3 or 4 bounces.
Also, you can use the Scene Tonemapper Scale in your world properties/Post Processing chain to overexpose your image, acting more like a camera.

[Ryan]

Tom has the best answer yet... dark textures!

Keep in mind that when you resized that scene, you drastically altered the texturing as seen by lightmass.

In the 1st image you posted, direct light is only affecting a small piece of the hallway on the ground. But that entire chunk is a dark purple square (part of the default texture) with only a tiny bit of the wall being white.
Because of the way gamma and lightmass works, a dark part of a texture like that will reflect VERY little light. To compensate for this, you can jack up the diffuseBoost in the lightmass settings of those assets. Note that this setting just makes the texture approach 1, it cannot make it brighter than 1 as far as lightmass is concerned.

In the 2nd set of images, you altered the texturing such that instead of just a purple square, you had light hitting 2 white square a little. That more than the scale change increased the apparent bounce lighting.

To rule out these issues, I suggest using the LightmassReplace node on your materials (yes even make your own default material), where you put in a lighter color like constant 0.75 or 0.5 into the Lightmass input.

This will mean lightmass always sees flat gray. Those of us who did lighting on most of gears3 ended up using the lightmass replace node for most of the game to get around issues like this. Oftentimes it is useful to use a vector parameter there so you can control the lightmass impact per material instance.

Also many materials require lightmass replace for technical reasons. For example RavensNest used worldcoordinates to generate the stripes on the walls (they werent in the texture). Lightmass has no concept of world coordinates or anything, so those materials would generate totally incorrect indirect lighting if we didn't just use lightmassreplace.

Texture brightness is by far the biggest issue in getting good bounce.

[Ryan]

If you rule out the brightness issues (by either actually brightening them, using diffuse boost, or lightmassreplace), then you can still get more bounce by increasing the IndirectLightingScale of your directional light. We've done that on a few gears maps, especially the sunny ones that have lots of orange bounce on the interiors.