Advice needed. Interior lit only with cove ligthing - light leaks VRaylightMtl

[Morne]

Hi all

I have a rather large interior lit only with cove lighting running in curved areas. (lighting hidden behind a cornice on the ceiling).
So I sweeped my "light" object to follow the path of the cove. This light object is away about 10mm from the cornice and wall and upper ceiling. I then applied a VRayLight Mtl on this object. I'm rendering using LWF and pretty high AA settings. Tried with DMC 1/100 and 0.003. Also tried 2/4, 0.003 and also 2/100, 0.003.
Lightcache is on 0.006 and 1200 samples.

Even with the above AA settings, I can only prevent light leaks by setting IR to "Very High" preset. This resolves the light leaks but creates, splotches. I remove splotches by setting IR preset on "Medium", but then I get light leaks again.

In the VRLight MTL I've tried various options (hmm although I didn't try setting the samples higher than the default of 8 yet)

I was thinking of making hundreds of VRaylights instead, but would have to make almost literally hundreds of lights due to the curves in the cove. This is using medium grey material for everything besides the covelight object

Any advice or suggestions?

[tricky]

Can't you use a vraymesh light? vraylightmtls need VERY high settings to render without blotches, especially if they are your only lights.

[joconnell]

Better again Could you use your curve that you swept as a distribution curve for regular vray lights? Flat plane lights that get cut out by the shape of the cornice model should be a lot quicker and cleaner than light materials. Could you pop up a wireframe of the scene?

[Morne]

@Tricky: the mesh light option is pretty much the same as the vraylightmtl except you have more options (in this case it gives same results)

@joconnell: yes I can do that, but then the light has to be very small to fit around the curves. I've had problems in the past when geometry cuts through vraylights.

I'm thinking of manually placing some vraylights and just resizing around corners with smaller curves.

(it's a shopping mall interior)

[Morne]

(click to enlarge)

I've deleted ALL mesh lights and in one section tried a normal plane VRayLight.
SAME RESULT!
Getting light leaks

anybody have a clue? (modelled in AutoCAD) so everything is excact without holes.

In the image you can see it seems the cove part is away from the wall and the light goes through there (but it is modelled correctly).
ALSO, on the top of the bulkhead it seems the ceiling is away from the wall ie. the light isn't "washing" up the wall nicely. Asif there is heavy contact shadow where the wall meets the ceiling.

[tricky]

Can you send me a bit of geometry (autocad and max 2009)? I'll see if I can take a look...

(we also model in Autocad)

[Morne]

@ Tricky (sent you a PM with email request)

[Morne]

AutoCAD and Max file attached in the ZIP

Here is a quick zip file containing a small test scene I created that gives the same problem

The zip contains a AutoCAD 2004 file and also a Max 2009 file vraysp3. Although the problem above was with Max 2011 and vray sp5, the problem remains the same.

CoveLight Problem.zip

Also herewith a screenshot of my usual import settings I use.

I've also tried unticking "Auto-Smooth"

[digitalx3d]

I assume you're using the Irradiance Map for primary GI right? Do you have the "check sample visibilty" option turned on?? This is great for eliminating light leaks, but at the expense of some render time.

[Morne]

I assume you're using the Irradiance Map for primary GI right? Do you have the "check sample visibilty" option turned on?? This is great for eliminating light leaks, but at the expense of some render time.

I can only see about a 5% difference when checking "check sample visibility". So basically it renders the "same"

Last night I remembered Vlado one time saying that this is caused by thin geometry (the cornice is about 10mm thick) so the IRMap can't sample enough in this areas properly therefore you need higher IRMap settings. Not sure then what causes the small splotches when using "High" and "Very High" presets.

Anybody have any ideas (besides making the geometry thicker than 10mm)?

[Morne]

Turning on "Detail Enhancement" in IRMap makes things about 40% better, but still getting 60% light leaks

[trixian]

Reset xform on the models might help? Sometimes I check if rendering with universal settings gets rid of the problem, but even if it does, it nearly always renders slow compared to having rebuilt the geometry. Buggy geometry from autocad\archicad etc. is a really big problem.

[Morne]

Reset xform on the models might help? Sometimes I check if rendering with universal settings gets rid of the problem, but even if it does, it nearly always renders slow compared to having rebuilt the geometry. Buggy geometry from autocad\archicad etc. is a really big problem.

Did that and it didn't do anything. The geometry is fine. And yes like I said earlier, rendering with sky high settings fixes it (sort off), but there is no reason it shouldn't work with lower settings and quick render times

[trixian]

Ok. Though in my experience, even though you inspect the geometry, and check it with various tools (stl-check\xview) it can still be bad. In fact, I am completely paranoid about mesh integrity now, as it has ruined stuff for me quite a lot.

[Morne]

Ok. Though in my experience, even though you inspect the geometry, and check it with various tools (stl-check\xview) it can still be bad. In fact, I am completely paranoid about mesh integrity now, as it has ruined stuff for me quite a lot.

OK Let me put it another way. The geometry is not fine, it is perfect. It was modelled in AutoCAD which gives much more accurate results (not that max can't, cad is just quicker). The light is not escaping because of bad geometry. It has something to do with smoothing groups on the file import, or just too low IRMap settings. Brute force even on low settings has no problems with the light leaks (but obviously grainy and to get it clean must be pused up VERY high so again defeats the aim which is to render in less time) IRMap with "Very High" I think will render quicker than Brute Force on for example 100? Just tried with Brute force on 200 and seems fine and clean (but now the light seems to be not working at all ie it is so faded I cant even see it - this is going to be a long day