Any idea why the U-Points are restricted to having a circular area of influence? There are many images whereby a rectangle and ideally a user-definable shape would be far more beneficial.
Well, I guess that they have stitcked to circles for the sake of simplicity, but you are correct, it would be good to be able to generate other shapes also.
As you probably know though, it is possible to substract one U-Point from another in order to avoid impacting one smaller area that would have been impacted by the main U-Point.
The main case where a non circular U-Point would be helpful is obviously sky like modifications. Since you end up covering the whole image with a sky U-Point, and this tends to affect blues in the lower part of the image as well.