Mesh Light Issue

[Design Union]

Faking IES lighting test.

I would like your views on the way I am faking IES lighting.
It is a very quick test scene, no exterior lighting just texture lighting. I have to find a way to show ies lighting within my scene as it is very important to show the client and I dont think Refractive Software will implement IES lighting before the end of this project.

So have a look and below the image is a description on how I did it.

IESmaterial

This is basic material unwrapping and I know it is going to be a lot more difficult when it is a more complex texture/model.
But in a nutshell I found a texture of a wall online. Then found a program that generates IES lights, now this program generates a preview of the light while editing.
So I took a screenshot of the light I made and put it within my image editing program (I use Gimp). The image of the light is Black and White so I place it over the texture and change the layer mode to screen or dodge, whatever looks best. I save the material, that will be used within the 3d program and I UV mapped it in my software (I use Blender). In Gimp I also create a Black and White(extremely high contrast, almost not colour), this will be used as the image for the texture emission material within Octane.
So when the model is imported within Octane and texture applied and texture emission played around with then you will see the result above.

I understand that this is a mission and a bit of a work around but I believe that this will just show the client correct lighting within the scene.
Also this is Direct Lighting and took 40 secs to render 1000 samples(that is the final above)

So please let me know what you think and if this is going to work, I need another perspective on this.
Many Thanks

[GeoPappas]

I'm no lighting expert, but I would think that the ceiling should receive lighting as well.

[Magog]

If u want, pending the IES Light nodes in Octane, u can try the plugin present in this tutorial for photoshop : LINK.

[abstrax]

I'm no lighting expert, but I would think that the ceiling should receive lighting as well.

I don't think this scene has a ceiling

[Design Union]

Hi all,

@abstrax: I had a look at the render again and it does look like there is no ceiling. But there is in the model, I think the combination of a lame material(grey Diffuse) and basic lighting, there is an illusion on no ceiling.
@Magog: I did come across that tutorial, even though I dont use photoshop anymore I saw still implement some of the techniques. I think if I spend more time working on the light material there will be a way better outcome.
@GeoPappas: Yes correct, I am going to have to work that out when the time comes. Maybe I can do a bit of editing on the final render and it will be okay.

I am just going to have to keep trying.

[abstrax]

Hi all,

@abstrax: I had a look at the render again and it does look like there is no ceiling. But there is in the model, I think the combination of a lame material(grey Diffuse) and basic lighting, there is an illusion on no ceiling.

Hmm, that's really weird. There must be no light going away from the wall then. Did you use direct lighting?

Cheers,
Marcus

[GeoPappas]

Hi all,

@abstrax: I had a look at the render again and it does look like there is no ceiling. But there is in the model, I think the combination of a lame material(grey Diffuse) and basic lighting, there is an illusion on no ceiling.

Hmm, that's really weird. There must be no light going away from the wall then. Did you use direct lighting?

abstrax:

The lights aren't real. They are images that are placed on a texture.

[Design Union]

@abstrax: Yes I am using Direct Lighting. The only lighting in this scene is the "fake" wall lights(the wall material is a Diffuse with the material of the wall and light then in the texture emission tab I placed an image of the light, just black and white, so where the white is shines the light) . I also used Texture lighting so thats what is giving me the Global Illumination.
This scene is within a closed box so no external light. I am going to have to sort out that light reaches the ceiling or maybe floor in other cases. But at this point I just wanted to see if I could fake it and then work on it looking better when the time comes. I am still in the modelling stage of the project and will get to materials and lighting next week so I will sort it out then.

[radiance]

Hi,

The issue here is that octane currently does not have a power/area conversion.
This basically means that the smaller the surface area of your lightsource is, the less power it will emit.

Therefore, if you have an object with 2x the surface area than another, both emitting, you will have to pass 2x the amount of intensity to the larger area light, to make it give a visually equivalent output.

The addition of power/efficacy inputs that use the surface area to calculate intensity will fix this, and it's on our short-term todo list for next releases.
IES won't make a difference here, it's just used to give another spherical intensity distribution.

Regarding render times, very small lightsources that are hidden, are currently not very efficient due to the lack of lightpaths (eg no bidirectional algorithm), which we are working on.
Simply using a lighting scheme that exposes the emissive surface in the room will speed things up considerably using path tracing.

Radiance

[Design Union]

@radiance: Thank you for your explination of the problem. I am going to work around it for the current project but cannot wait to use the updates in the next Octane Release.