This mask is a Solid positioned with a 2D Placement Defines a placement in 2D space Read More . It has feather parameters that can operate on the four sides of the mask.
This mask can be used to create soft-edges when doing multiple video-projectors overlap. In this case, think to put the Gamma parameter to a realistic value such as 2,2 for example.
Note that similar and more evolved masks can be obtained by combining a Layer mask Turn any 2D generator into a mask Read More with a Uniform Generate a solid, uniform image, filled with a unique color Read More .