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- Each new SL takes approximately twice x1.5 times as long to reach as the previous one. If it took 15 10 minutes to go from SL 4 to SL 5, it will take about 30 15 minutes to go from SL 5 to SL 6.
- It is uncommon needing to render beyond SL 19 - 20.
- The difference in noise levels becomes increasingly small as the SL increases. This means that there can be quite a difference between SL 5 and 8 in terms of noise, but very little difference between SL 18 and 20.
- It would be counter productive to be "fanatical" about an absolutely clean render, as even footage shot on a high quality digital camera will have a slight amount of digital noise. Try to evaluate if a slight noise reduction in post will help to get rid of too evident noise, and thus saving you a lot of render time. Remember that each SL takes approximately 1.5x longer than the previous one. Lets say your render has a little bit of noise left at SL 16 and it took 15 minutes to get to this SL. But you wish to get rid of the noise completely, which would happen at say SL 20. The render will reach SL 20 in about 114 minutes. That's more than 7x longer render time, when perhaps stopping at SL 16 and doing a slight noise reduction in post would have been more than adequate.
Sampling Level vs Time
There are two ways to stop a render in Maxwell Render: by setting a Sampling Level or by setting a Render Time (in minutes). If you set both parameters, the render will stop when the first one is reached. This double approach gives you a lot of flexibility to control the quality and time invested in rendering. For example if you want to quickly compare a few renders of a scene you can set the time low (ex. 10min) and the SL high (ex. 15). In this case it is improbable the render will reach SL 15 in 10 minutes, so the render will stop after 10 minutes. For a final render you should set the SL to the desired level and set the time to a high value (ex. 999 minutes). Maxwell Render will stop when the SL is reached. If the render needed a higher SL you can always resume the render. See How to resume a render for more information.
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At the beginning of the render, the Sampling Levels increase faster, and the main render view in Maxwell.exe will update with each new SL reached. As the render goes on however, it will take longer and longer to reach the next SL, and so the main render view will update every 10 minutes. You can also choose how often to update the main render view from the Maxwell.exe preferences (File>Preferences). It can be useful to set this time to a higher minimum because each time the render view updates, Maxwell writes a new version of the MXI file to disk and the rendering stops until it has successfully written that MXI, then resumes the render. To avoid this pause/resume/pause/resume especially at the beginning of the render, you can set a minimum write time to 15 minutes or more for example. Please see the Preferences section at on the bottom of the User interface and menus page for more info.
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An MXI file is always written to disk when Maxwell renders and it updates with every change in SL. If you don't specify an output path for the MXI file, it will be written to your systems temp folder. It is always a good idea to specify an output path for the MXI when rendering, not just an image output path. This will ensure you can always resume a render, even if the systems temp folder is purged, and it allows you save several versions of your render using different exposure or Multilight settings, without having to re-render.
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| On In Maxwell 2.7 we have introduced a transparent, loss-less compression system for both MXS and MXI files. Compression ratios are excellent when rendering additional channels such as alpha, shadows or ID's. With all channels activated, the MXI file can be 4x smaller. The compression system does not affect save performance more than 1-2%. |
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*Images with embedded alphas can use the alpha as a layer mask