Mesh Light Issue

[Design Union]

Hello all,

I have just started my first project with Octane and have run into a problem.
I work with an Interior Designer and as most architects and interior designers the lighting is very important to portray what they have in Plan. Now I totally understand that IES lights are avaliable yet, which is fine I have been trying to find ways around it with Mesh Lights.

So attached you can see that I have an interior corridor(very basic model no textures)
The issue is with the wall light on the left of the render. When it is on by itself (no other mesh light materials) then it works fine.(this was a quick render so quality is low)
Now the scene has many lights which has made me create more then one light material within Octane. For the wall light I had to put the power of the texture emission to 500-1000 to get the intensity needed, then the ceiling bulkhead lights are another material with a texture emission at 5. Firstly I find this strange at the vastness of intensity these materials.
As soon as the 2nd material (bulkhead light) are changed to a mesh light then you can see the result in the Image 2lights_3min_direct. The wall light just disintergrates.
Is there anybody that can help me find a solution to this as the rest of the project has many scenes with this scenario.
Also I am doing an over night render using Path tracing to see if the problem is there. The reason for using Direct lighting is becuase I have no time to finish all the renders in time of deadline and the renders are extremely noisy(using Path tracing) unless the render is left for 10 hours. The other issue is that the render size will be A3/A2 and when I have a full scene and A2 size then put on pathtracing it just freezes and Octane closes(I have tried LensShift to render sections and will maybe use it) but I have decided to use Direct lighting for now.

1 Light material used (wall light)

2 light materials used (wall light and Bulkhead)

[kubo]

do you have normalize turn on? if so (and if I understand it right) normalize "equalizes" the ligth powers of all the emitters on the scene, the surface of the emmitter has a great impact on how much it will "light" compared to one another. So now your tiny wallwash lights compared to the ceiling one is ridiculous, hence the low emmission. Turn off normalize and cranck up the light power of those lights compared to the ceiling one.
Hope it helps

[Design Union]

@ Hubo: Thank you for you reply, I searched the forums again and saw you have answered other people with similar issues.
But unfortunaly the normalize did not work, have a look at the renders below.
Has anybody come across this issue or is there anyway around it.
Could anyone from Refractive software please let me know that I am not tripping and that there is a simple solution.
Any help with this will be greatly appreciated.

Have a great day Octane users.
1 light material with normalize off using Directlighting

test01_1light_direct_off

2 light materials with normalize off using Directlighting

test02_2light_direct_off

2 light materials with normalize on using Directlighting

test03_2light_direct_on

2 light materials with normalize off using Pathtracing

test04_2light_path_off

[kubo]

first think that directlight does what it says, just direct, no rebounds, no GI. So in order to use it play with the aodist value to match your scenes scale. Keep in mind that you are using indirect ilumination on most cases on your scene so pathtracing would be much better cause you would get light bounces, in particular if you up the maxdepth value. Also don't forget to play with the camera's ISO and f value, specially with DL. I remember seeing some problems like the one you have with previous versions of octane, but not with the more recent builts.

[Design Union]

@Kubo: Yes totally understand, direct lighting is basic but in terms of Time vs Quality, time wins this round. So I am having to have a lower realistic quality but will able to finish on time. I also downloaded the latest version of Octane(I was using 2.4 and now got version 2.44).

Well I have been doing many tests today to find a solution to the problem.
What I have found is that very small emitting mesh lights really lack in quality(I am trying to simulate LED lights) . If you look at the render the 2 lights on the brown wall opposite the orange light on the silver strip. They have 100% power and look at the brighness of it! The orange light in between then has a power value of 10 and is brighter then the 2 lights, I cannot rap my head around how this is happening.
I understand that octane is simulating real light properties but I am just not able to get the required results. I will just have to keep testing and wait until Refractive implement IES lighting.

If anybody has any ideas or solutions for interior wall lighting that can "fake" ies lighting please let me know.

Direct_multilights_1min

[GeoPappas]

How many faces/triangles do the lights have? If the lights have a lot of faces/triangles, it is possible that is causing a problem.

[bepeg4d]

unfortunately it's an old problem, look at this old post:
http://www.refractivesoftware.com/forum ... led#p35448
i hope that they could get rid off it in the future
ciao beppe

[mkh42]

Hello

The problem with the small ligts is imho related to the unidirectional pathtracing algorithm Octane is using.

Take a look here to get a quick overview over pro's and con's of existing algorithms

http://raytracey.blogspot.com/2011/01/w ... -real.html

greetings
mkh42

[Design Union]

Firstly thank you all for you comments.

@GeoPappas: I was actually worried that it was because of to little faces, the light sources are planes with one face. I did do a test with more polygons on the face but still had the issue.
@bepeg4d: I was searching long and hard in the forums to see if anyone was having the same issue, cant believe I couldn't find your post. I saw that your post was at the end of last year so hopefully they are working on it.
@mkh42: Thank you so much for the insightful link, really gives easy to understand descriptions about the various renderers. I knew Octane was not great for interiors to begin with, but I know I will be able to work with it to get the required results.

The only quick solution I can think of is to map the light onto the wall material but only the specific areas where the lights are affecting the walls of course. I am going to do some experiments next week and will show anything if I have come up with a work around.

Thanks Octane people

[Design Union]

Just a quick update.

So below is the render that I left on after work on Friday.
Render time is 8 hours 54min
Max Depth is 32
Max Samples is 64000

Pathtracing

Rendertime is unrealistic for large size renders but hopefully I can find the time to do it as the quality is a lot better then direct lighting except the noise interior scenes create.