OTOY Forums

A general rule of thumb: Try to work in a DS or Poser scene, like a cinematographer would do it.
When showing an interior scene, you usually don't show more than 1-2 walls, maybe 3 at best.

This means, you can open up one wall of your room, and let some light (preferably generated by an HDRi image) stream through it, really helping with your interior lighting.
This essentially comes at the cost of nothing, since it's all happening off screen, but can really get rid of that nasty render noise.

You can also cheat and clear the "Shadow visibility" property for the room as discussed here: viewtopic.php?f=44&t=51514
That lets you put all your lights outside the room and lets the light go straight through the walls.

TRRazor wrote:All methods previously suggested are meant to take care of the symptoms, but never really cure the actual problem most users have with photometric lighting.
Try to light the room REALLY brightly and very evenly, don't leave a single spot unlit.

Then, use the exposure to achieve the light mood you want in the room. (By lowering the value you'll get darker moods, by setting it higher, you'll get brighter moods.).

I come from a photography background - the method described above is the same movie sets are lit - try it, you'll see, it works and it will get rid of that nasty specular noise
When done right, you'll never ever need Hotpixel removal, GI clamp and or caustic blur EVER again.

Remember: Hot pixels in a room only appear, when there is not enough lighting information for the renderer to return!

This is amazing.

I just wanted to comment on this to thank you for this really valuable and non-intuitive information.

Although I would consider myself fairly knowledgeable about filmic techniques and production, this is something I never knew about as I never had much focus on lighting. These physical principles apply completely to Octane (which would make sense as it's a physically based renderer) and have totally saved the scene I'm working on.

I think this is really important because it really requires a fundamental shift in how the artist thinks about constructing scenes. I know for me, coming from more of a general graphic/motion background, I think about things in terms of WYSIWYG. When I paint a pixel, it is that color.

The idea of overexposing in order to get more lighting information seemed initially counter-intuitive and again thank you for relaying that knowledge, I'm sure that will greatly come in handy down the road (and it already has)!

You're most welcome, glad that it helped with your work

*EDIT* Be careful not to actually overexpose, because once texture detail is "burned out" from lighting, you'll never get it back.
Essentially the workflow should be like this:

- Set up scene with props, characters environment you want to use, apply shaders if wanted.
- Evenly light the scene, either with emitter lights, or by removing one wall of the room / building to let light stream in from an HDRi.
- Adjust your exposure according to the lighting mood you want to achieve.
- Check if your lights are "burning out" texture detail in areas (especially the areas close to light sources and/or bright materials) adjust light power accordingly
- Check for areas were render noise is overly present - if encountered - you need to adjust your lighting, or add additional light sources in that area.

- Render your scene!

This thread helped a ton. Especially the reducing the GI clamp trick. I'm getting renders on Pathracing quicker than DL thanks to that little trick.