Rendering issues when stitching regions (3rd party render managers only)
If you are using the noise level limit and render your image as multiple regions, which are then stitched together to produce the final result (e.g. when rendering through various 3rd party render managers such as Thinkbox Deadline, Autodesk Backburner, or some kind of in-house tool), you will most likely end up with an incorrect end result. This includes "splotches" where the edges of the regions meet, brightness differences between the regions, quality differences between the regions, and other.
Solution: use pass limit instead of noise level limit to determine the quality of each individual region. When using the noise level limit, each region may end up with different quality (since Corona Renderer may interpret the same noise level differently for different kinds of images). Using the pass limit will guarantee identical quality for each of the regions, which will be then successfully stitched together.