Three types of layout objects help you to position objects relative to each other: layout curves, two-dimensional (2D) layout grids, and three-dimensional (3D) layout volumes (also called volume grids). Each type of layout object has anchors to which you can attach objects. All use nodes as anchor points. Layout grids and layout volumes also provide cells as anchoring points for cell anchors and volume anchors.
By defining an object as a layout curve and placing nodes along the curve, you can position objects precisely along a path. Layout curves are useful for positioning wash basins along a wall or rafters along a roof.
A layout grid is an arrangement of rectangular or radial spaces, called bays, that are delineated with parallel or radial lines. Use a two-dimensional (2D) layout grid to position objects in a grid pattern. Anchoring objects to layout grids might help you to position planters in a sidewalk grid, or tile accents in a floor tile grid.
A layout volume (also called a volume grid) is a three-dimensional (3D) arrangement of rectangular spaces. Use three-dimensional (3D) layout volumes to position objects on a multilevel grid. Changing the size of a layout volume changes the spacing of objects attached to that grid and can also change the size and height of objects attached to that grid.