[JTB]

I have to make two daylight exterior renderings and one nightshot.
My daylight images can be OK with SL 12 (maybe some noise cleaner to improve it) but my nightshot is still very noisy even after SL 12.00
I could compare it with SL 6 or 7 of the daylight pictures.

So, I guess now you can understand the title....

I know this has been asked and answered before but I would be very glad to hear an explanation... Thank you in advance

[Kabe]

SL is a unit for the calculation time, and usually it takes more time (=higher SL) to get noise free if there is little light in the scene, ie at night.

Hope it helps

Kabe

[JTB]

SL is a unit for the calculation time, and usually it takes more time (=higher SL) to get noise free if there is little light in the scene, ie at night.

Hope it helps

Kabe

Thank you for your answer but I thought that SL was not related to the scene but time to reach that SL was...
I mean SL 19 should always give us a clean picture but to reach SL 19 in a nightshot you would need twice the time for a daylight scene...
This is not happening.... My SL 19 nightshot now looks worst than my SL 13 daylight rendering.

So, I woudn't call it a unit, because unit should be something unchanged... 10m>5m but 1m is always the same...
So, SL (Sampling Level, right?) should be the same for two pictures that look the same but achieved after different rendering times.

OK, I don't know if I can explain it well.
So, now that I have a SL 19 and I read Next SL : 18h15min for example, what should I do?
If I try to check my white color (<235) or my reflections or... I have to start again and that means that I just lost 11h of rendering!!!

[beatriz]

The SL needed will depend on the type of lighting (indirect/direct) and the type of materials mainly (SSS needs a higher SL than a metal to be clean).
I hope it helps.

[tom]

SL means Sampling Level. Rendering in Maxwell is an unbiased process, which means it will calculate bounces of light forever without any optimization and shortcut. Since it's impossible to finalize the infinite calculations without pressing stop, Maxwell has to show the reached result with intervals. These are samples. Every new sample will be more meaningful in terms of perception. The reached quality in a sample depends on scene lighting/material conditions. With more challenging stuff like heavy materials with many BSDF and/or lots of emitters and or a few small emitters/far emitters and/or relatively dark scenes will suffer about quality per sample comparing to the well illuminated ones. Therefore, the quality reached in every sample is relative and it depends on your scene. As a common sense SL19 may be enough, but sometimes SL22 wouldn't be enough, too. The correct saying is, SL+1 is always better than SL and required satisfactory SL for every scene can change.

[JTB]

Thank you all, I guess the only important thing is what you see on the screen...

[def4d]

so it is useless?

[beatriz]

so it is useless?

Not at all, in fact is very important to understand how Maxwell works.
I can foresee the sampling level needed in my scenes by the materials and lighting used, and therefore have a rough idea of rendering time. Just to put an example.

I would say it's a reference value you have to be aware of in your renderings. To know what's going on.
Let's say you disabled the display during rendering (it's faster), SL will tell you how is your image going.

[tom]

so it is useless?

I've heard people find things useless when they couldn't understand the benefits, maybe you should read again and try to understand why it's useful. If you find it useless in the end, don't let it bother you, it's just an innocent increasing number allocating a few pixels on the screen.

[Jozvex]

SL is very useful when rendering animations, though I know not many people are doing that.

I render out a frame from the sequence I feel will be the slowest to clear up, stopping it *just* as it becomes acceptable. Let's say that was SL 14. Now I know I can set all my frames to render to SL 14 and I'll have a good time-vs-quality balance.

[bjorn.syse]

I agree with that Jozvex.

[JTB]

I've heard people find things useless when they couldn't understand the benefits, maybe you should read again and try to understand why it's useful. If you find it useless in the end, don't let it bother you, it's just an innocent increasing number allocating a few pixels on the screen.

[zoppo]

Let's say you disabled the display during rendering (it's faster), SL will tell you how is your image going.

What speed difference is there to gain by disabling the display?
1%? 5%?

[beatriz]

It depends on the resolution and it's non-linear, meaning on the firsts iteration you will gain time, but when rendering iterations space themselves the gain is not so noticeable.

You can also render by command line to improve render time and memory usage btw.

[Jozvex]

This is all an assumption but,

zoppo, you know how when you're rendering it gets to the next 'update' and it'll say 'Waiting...', before updating the image? You'll eliminate that waiting time. I assume the 'Waiting...' is displayed while it does the spectral-to-RGB conversion and then replaces the image in the display?

If that assumption is correct you could save quite a bit of time because those 'Waiting...' pauses get longer and longer with each update, because there's more data to convert?

In truth I have no idea, haha, but that's my guess.