By JDHill
I'll need a bit more to go on; could you please email (jeremy at nextlimit dotcom) or upload (using dropbox or similar) a SKP that I can use to reproduce the behavior?
By tavih14
Hi JD, i've corrected the issue, there was a lot going and I was a simple fix, but I do have other questions concerning noise. I read up on a different post with the same issue, but i still quite cant figure it out. I had better luck with a night rendering, i added enough lights to get it to not have noise.

I set it to 20SL but stopped it at 15.


I STopped this day rendering at 12.


I know u need more info, im just not too sure as what to provide.

Thanks for the help.
By JDHill
It looks like the energy is out of balance in the scene, meaning, the material colors, the camera exposure, and possibly emitter & environment power values, are not being kept in realistic ranges.

The white material looks very bright; considering that the render engine is simulating how light really behaves in the scene, if surfaces are assigned materials that return more energy than they would in the real world, the light rays live too long, creating noise, and taking time & CPU. The R, G, and B values of a material color should generally be kept below the 230 range, since that is about the brightest value you are likely to encounter in reality.

Next, the camera should be set to use a realistic exposure; I would guess that to be around EV 11-12 in the daylight scenario. If you have to use something that seems unrealistic, it should be taken as an indicator that the energy is out of balance somewhere. You can find a chart of EV (Exposure Value) values for various situations on this page.

Emitters should be set to use realistic values, even if this means you cannot see their contribution, since that is how it is with a real camera, as well -- you cannot expose both for weak and strong lighting simultaneously. And if lights cannot be seen contributing, it may be good to disable them, since they will still be calculated, and will therefore slow down the render.

Lastly, make sure that environment power values are set to defaults (i.e. 1.0); you can increase the sun and sky intensities, but that should only be used in situations where it is done for stylistic purposes. It is possible, though not very realistic, to decrease render time somewhat by increasing the sun radius, though this will soften the shadows it casts.

So please review these factors and see if they help.
By tavih14
Hi JD,

I definitely had better success, but still very grainy. I stopped it at sl 15, set it at 20, showed no difference since sl 11. I adjusted per your comments and by the chart you sent me a link for.

By JDHill
Scenes such as this typically need SL 20+. Other suggestions for reducing render time might include removing window panes if you don't actually expect to be able to see reflections in them, and making sure that you are making use of you CPU threads -- a threads value of 0 (it is in Maxwell Fire settings) tells the engine to auto-detect and use all available threads, but you probably don't want to use that until you're finished working with the scene, and can leave it alone to render the final image, since it can make SketchUp (and the machine in general) pretty sluggish. I would also say to make sure to render final images with the Production engine, but it looks like you're already doing that.
By tavih14
Hey JD, its looking a lot better. Definitely better than the first couple of renders. The only thing that I noticed is that the floor under the stairs is looking a little weird. I'm assuming i just need to adjust the material a little bit. This took about 3.5 hrs to render, I'm assuming adding more objects and more materials will make it take a little longer?

By JDHill
Regarding the last question, the answer is yes or no, depending. If you added some new window panes, made of a completely black material, such that no light entered the room, then your rendering would be finished the moment it started, since with no light, a black screen is the finished rendering. And if you then cut a pinhole in one of those new window panes, letting in a miniscule beam of light, then your render might take until the end of time to complete. In other words -- it's not about how much you give the engine to render, but rather what you give it.

Which leads to the answer about that spot under the stairs; my guess is that this is either a reflection following the path sun > glass table > reflective ceiling > floor, or that there is an accidental hole in the wall or ceiling, off-camera, up and to the left. Which leads to one more type of shortcut that can be applied: putting a completely diffuse and black material on surfaces which cannot be seen (the underside of some of the stairs, or perhaps the high ceiling), the purpose of which is to stop light bouncing around in the scene. Naturally, this will have an effect on the realism, though, so it is something to try, and only to use, if the results are acceptable.

And lastly, it could just be designed that way, but my instinct is to check that last cushion on the sofa, to see whether it might not have the white sofa material applied to the wrong side of the faces -- meaning that it is white inside, with no material assigned to the outside.
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