Objects are collections of points, polylines (a series of connected line segments), and polygons drawn in the main window of ModelMuse or imported from external files. Objects can have one or more sections; each section is a point, polyline, or polygon. For example, a torus would be represented by an object with two concentric polygon sections. In the direction perpendicular to the plane in which it is drawn, an object can have formulas for zero, one or two surfaces. An object with zero surfaces is two-dimensional because it has only two coordinate directions defined. All objects, including point objects, with at least one surface defined are three-dimensional because they have three coordinate directions defined. Objects with two surfaces have an upper and lower surface making them three-dimensional. For example, a polygon with an upper and lower surface is a solid. The surfaces associated with an object need not be flat. The surfaces are defined by formulas that allow them to have virtually any shape. There is one limitation: none of the line segments defining an object can cross another line segment of the same section of the same object.

Objects drawn on the top view of the model that have two surfaces can apply to more than one layer at any one column-row location, whereas Objects drawn on the top view of the model that have one surface can apply to only a single layer at any one column-row location although the layer may vary among locations. Objects drawn on the front and side view behave analogously. In SUTRA models and MODFLOW 6 models that use DISV grids, objects drawn on the front view store the angle of the cross section. If the angle of the cross section is changed, only objects on the front view that have the same angle as the current angle of the cross section will be visible.

Objects are used to modify the default values of data sets and to set boundary conditions. Objects can be used to set values of data sets in any of three ways: (1) in two-dimensional data sets, values can be interpolated among objects (see Interpolation Methods); (2) values can be set for elements or cells whose centers or nodes are enclosed inside the object; and (3) values can be set for elements or cells intersected by the object. For the latter two methods, the order of the objects is important. Because each object overwrites previous values, only the last value applied takes effect.

Note: For a polygon with two Z formulas, “intersected” applies to cells that intersect the shell of the object defined by the vertical edges and the horizontal top and bottom surfaces but not the cells that are completely inside the shell. For a polygon with zero Z formulas, “intersected” applies to cells that intersect the edge of the polygon but not cells that are completely inside it.

See "Creating, Selecting, and Editing Objects in ModelMuse" and "Object Properties dialog box" for more information about Objects.