General Interior Lighting Question

[Banti]

I am currently facing the challenge of setting up some interior scenes with characters in them. The problem i have is that making the interior AND the character look both, decently realistic and still well illuminated is bit difficult to say the least. So i do have a few questions regarding interior lighting.

1) Is there a consensus if it is better to use and HDRI or the (new) Octane Daylight for the general "ambient light"? In terms of brightness i need to raise the power of either to something between 15-30 just to have the interior "okay-ish" illuminated. But setting it this higher tends to burn out windows and the floor.

2) Is it a good idea to use small light sources to simulate ceiling lights? Say i use 2 "smaller" emitting spheres on the ceiling. Because i remember reading that small light sources can be quite noise heavy. But what is considered to be small?

3) Maybe someone can share some tipps and tricks about lighting characters indoors while mantaining a somewhat realistic look. I am not talking about photorealism, i just dont want lightsources to come from nowhere in the scene, that about it.


Thanks

[rajib]

Hi Banti,

HDRI generally produces better overall illumination in general than Octane Daylight in my opinion. But be careful with the sun direction the HDRI.... In octane if the sun in HDRI is in front of the camera, it produces darker ambient light than for the same scene if the light is behind the camera. You can even place a large light source outside the window to simulate sunlight.

Small light source = darker shadows and harsher light. Large light source = softer light and shadow. So based on the look you want, you may have to control the size of your ceiling lights. If the lights sources are visible in the scene then I guess you will have limited choice but you can replace them e.g. use tube light instead of a light bulb or big hanging lamps with shades instead of naked light bulb to have a larger light source. But if the light source is outside your scene view then I would say use larger light source to create a softer light. It will also add to the ambient light. Be careful of what reflective surfaces you have in the scene because your light source will reflect on them. To get a realistic look, just play around with the light settings and size. But if you have characters in the scene, the skin materials you use will play a major role it making it look realistic.

Regards,
Rajib

[Banti]

Hi Banti,

HDRI generally produces better overall illumination in general than Octane Daylight in my opinion. But be careful with the sun direction the HDRI.... In octane if the sun in HDRI is in front of the camera, it produces darker ambient light than for the same scene if the light is behind the camera. You can even place a large light source outside the window to simulate sunlight.

Small light source = darker shadows and harsher light. Large light source = softer light and shadow. So based on the look you want, you may have to control the size of your ceiling lights. If the lights sources are visible in the scene then I guess you will have limited choice but you can replace them e.g. use tube light instead of a light bulb or big hanging lamps with shades instead of naked light bulb to have a larger light source. But if the light source is outside your scene view then I would say use larger light source to create a softer light. It will also add to the ambient light. Be careful of what reflective surfaces you have in the scene because your light source will reflect on them. To get a realistic look, just play around with the light settings and size. But if you have characters in the scene, the skin materials you use will play a major role it making it look realistic.

Regards,
Rajib

Thanks you so much for you answer
You are right, the skin material was as major issue for me when it comes to light. I really love the new random walk SSS and the skin it produces. It looks phenomenal with HDRI lights only. But the problem is with interior scenes, i cannot overlight the scene or else the room looks terrible. But if there is not enough light, the random walk Skin look terribly noisy an just not good. That was incredibly frustrating and i needed like 10.000 samples just get rid of the noise in the skin. So in the last days I've gone back to RedSpecc Shaders, and they work really good with the light in interiors.

Another question. Lets say i want to have an evening interior scene. I would have an emitting ceiling with very low power just for the overall illumination. I want to introduce some candlelight in the scene. Is it ok to make the top of the candle itself an emitter or would that introduce too much noise? Like i said, i have read that "small" light sources are noisy. I could put a small sphere on top of the candle. Is a sphere geometry that is scaled down to lets say 5% too small or is that a good idea?

Thanks

[rajib]

Thanks you so much for you answer
You are right, the skin material was as major issue for me when it comes to light. I really love the new random walk SSS and the skin it produces. It looks phenomenal with HDRI lights only. But the problem is with interior scenes, i cannot overlight the scene or else the room looks terrible. But if there is not enough light, the random walk Skin look terribly noisy an just not good. That was incredibly frustrating and i needed like 10.000 samples just get rid of the noise in the skin. So in the last days I've gone back to RedSpecc Shaders, and they work really good with the light in interiors.

Another question. Lets say i want to have an evening interior scene. I would have an emitting ceiling with very low power just for the overall illumination. I want to introduce some candlelight in the scene. Is it ok to make the top of the candle itself an emitter or would that introduce too much noise? Like i said, i have read that "small" light sources are noisy. I could put a small sphere on top of the candle. Is a sphere geometry that is scaled down to lets say 5% too small or is that a good idea?

Thanks

Are you using Denoiser ? Render Settings Sub Tab in the Octane Tab : Enable Denoising - ON / Denoise Volumes - ON plus have the Denoise ticked in the System sub tab : Open Device Setting and have at least one GPU ticked for Denoise. If so it should denoise the scene very fast. Even 1000 samples will get you a clean scene.

For the candle, yes add the texture emitter and use the fire texture of the candle light in it. You can reduce the Distribution to a low value so that the candle light does not contribute much light to the scene but is seen correctly. You can also set the Distribution to an grayscale image and set an IES light map to it to control the distribution. If you have not used IES light before please take a look at viewtopic.php?f=44&t=52741.

[Banti]

Are you using Denoiser ? Render Settings Sub Tab in the Octane Tab : Enable Denoising - ON / Denoise Volumes - ON plus have the Denoise ticked in the System sub tab : Open Device Setting and have at least one GPU ticked for Denoise. If so it should denoise the scene very fast. Even 1000 samples will get you a clean scene.

For the candle, yes add the texture emitter and use the fire texture of the candle light in it. You can reduce the Distribution to a low value so that the candle light does not contribute much light to the scene but is seen correctly. You can also set the Distribution to an grayscale image and set an IES light map to it to control the distribution. If you have not used IES light before please take a look at viewtopic.php?f=44&t=52741.

I actually didnt work with the denoiser, not sure why. I will definitly try that. But the problem with the Random Walk SSS is more that in interior scenes there just isnt that much light which means it takes way more samples for the skin texture/details to appear. Sure the denoiser gets rid of that but the detail is not there until about 5000-10000 or so samples. Im still trying to find a solution to this. Also, the facetting issue with SSS is still there, so closeup shots still require SubD levels of 3+ which makes my viewport lag with more than one character in the scene. But like i said, the RedSpecc Shaders still work fantastic in pretty much every setting. I do like the IES idea. I have worked with that before. Thanks for that.

I very much appreciate your tipps, thanks you very much