Internal Lighting and Render Load

[Spectralis]

I'm using the latest build of v3 and trying to find ways to light an office scene I'm working on. I tried some of the suggestions in the link in Paul's signature to reduce noise which have helped but there is still the problem with the length of time the render takes. I've had some ideas to reduce render times and noise but often this isn't due to scientific understanding but through vague guesswork. I wonder if others could advise if they're worthwhile or not and offer their own suggestions.

1. Choose a lower resolution HDRI that introduces maximum light. Or reduce the size of the HDRI in the plugin or in a photo editor. I've tried reducing the size of the HDRI in the plugin by half but this causes a reduced colour palette so probably best done in a photo editor first.

2. Choose materials that aren't too reflective or too heavy on render load. I'm often unsure which textures use less resources and don't throw lots of light around. For example which texture to choose for a reflective floor surface that's not too resource hungry or bouncing light everywhere? Textures can add to the render load but can they also increase problems lighting a scene?

3. Choose a few large planes with texture emission vs lots of smaller strategically placed planes using Blackbody emission (e.g. as florescent strip lighting.) I don't know whether it makes any difference resource wise using a couple of large emissive surfaces vs lots of smaller ones. Or if there's any difference resource wise between texture and Blackbody emission.

4. Is mixing HDRI and emissive lighting a good idea and how to do it so that each enhances the lighting rather than cancels each other out?

5. Reducing specular and diffuse depth (e.g. diffuse = 8/Specular = 24 > diffuse = 3/Specular = 9). This significantly reduces render times - each time the diffuse/specular level is reduced by half the render time is reduced by half. When I reduce these levels the scene becomes darker what's the best way to counteract this? What is the effect of reducing diffuse/specular on the scene apart from darkening it? Will these levels affect glass and other transparent/reflective materials?

If there was a book or series of tutorials about setting up lighting in Octane I would definitely buy this in case anyone is thinking of producing them.

[Hydra]

I think you should describe what you're trying to do first...

Image resolution... bigger = slower

For me, the biggest issue is using specular materials for glass in windows. I fake that out and the render settles fast. (I use a fake reflective glass.)

I don't generally work with HDRI, but sometimes I'll use environment for lighting. Where possible I avoid both of those and fake it out. I'll place a giant emitter to simulate sky lighting a scene.

[Spectralis]

Nicely lit scene Hydra. Did you render using direct lighting, path tracing or pmc? I'm trying to light an indoor office scene as naturalistically as possible. Using HDRI and emitters works well in path tracing but the lower the specular and diffuse levels the less realistic it looks and the faster it renders. The fake glass is an interesting idea but I'm not sure how to achieve that.

[Hydra]

I used Path Tracing for pretty much everything.

Here's my fake glass;