Its always sitting there mocking me. I dont know what it does.
What does it mean ? and arnt all pixels square in the first place ?
bonus internet points if you use sock puppets 
Iām not a native but i feel āSquaredā (math x*x) would be more intuitive.
This is nothing to do with squares and is pretty clear when you select Branched Path Tracing from dropdown: see a bit down ray sample counts while you check/uncheck Square Samples. And itās a time killing feature ;).
aah squared samples. they didnt put the D on the end.
seems a bit pointless.
I thought it had something to do with taking into account pixels within a square around the main pixel.
Iāve always wondered the same thing Humblerollerā¦based on eppoās comment, itās nice to know I havenāt missed anything that important.
From the 2.69 release notes: Add a āSquare Samplesā option to the Sampling panel, to use squared values for ease of use. This can make tweaking easier from an artist point of view. (r58424)
https://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=58424
i dont see how it makes it easier. its just less clicks and more maths.
Itās bringing Cyclesā Branched Path Tracer closer to Arnold in the way you set sampling levels to reduce noise. It often takes a lot of additional samples to reduce noise levels in a noticeable way, and the āsquaredā setting makes it simpler to make those changes. While it may give you more samples than you ultimately need (especially once you get over 4 or so), itās a lot quicker than trying to determine whether or not you should use 400 vs 425 diffuse samples, for instance.
jdent hit the nail on the head.
I added it (Iām an unabashed Arnold user).
Basically, the longer the render, the more samples you need to make a noticeable difference in the noise level of your image. It just happens to work out that, when you measure noise, the graph plots very similarly to a simple x^2 graph. So, when using branched path tracing, this makes it very simple to turn up the sample for the pass where you are getting noise by 1 and get a real boost in image quality. Rather than sitting and trying to figure out how to balance huge numbers of AA, Diffuse, Glossy, etc. samples, it allows the artist to keep a very simple mental list of good starting values for different lighting situations and blur situations.
ahh good to know.
Iāll use it then.
Glad I got it right. I canāt remember where I saw it but I was basically summarizing an online explanation that I saw from the author of the feature. I didnāt make the connection :o