This figure shows four squares, each containing a different grid. On the left is an 21 by 21 grid, equally spaced in both directions.

Next is a 21 by 31 grid, equally spaced horizontally, and with points clustered near the bottom edge. The grid spacing on the left and right edges is the same.

The third square has a 31 by 21 grid, equally spaced vertically, and with points clustered near the left edge. The grid spacing on the top and bottom edges is the same.

The last square has a 31 by 31 grid, with different grid distribution functions used on all four edges. Along the left edge, grid points are clustered near the bottom. On the top, grid points are clustered on the left. On the right, grid points are clustered near the top. And along the bottom edge, grid points are clustered near the middle.