Hi, I’m using OvalPortrayal2D(6) to display large disks and OvalPortrayal2D() to display small disks and I need to know when the small disk overlaps the large disk. Is the location of a disk given by its center? If so, then if I knew the radius r of the large disk, I could use something like: Bag bag = baysim.fishSpace.getObjectsExactlyWithinDistance(myNewLoc, r); where myNewLoc is the location of the small disk. This should return all the large disks whose centers are within r of the center of the small disk or, equivalently, all large disks containing the small disk. My question is, what is the radius of the large disk OvalPortrayal2D(6)? Does scale 6 denote the number of units across and hence the diameter of the disk? Would this be the correct way to determine if the disks overlap or is there a better way? Thanks. Joaquin