AutoCAD Map 3D uses polygons by default for import and export. If you do not want to use polygons, for example, for compatibility with an older drawing, you can select the option to import polygons as polylines. You can also change the default setting for this option.
When objects are imported as polygons, they use the default fill color and pattern set by the MPFILL command. Boundaries come in as usual, using the default layer color unless another color is specified in the imported file.
You can change the default fill color and pattern assigned to polygons. For color, you can choose from a variety of colors including true colors and colors from imported color books. For fill pattern, you can select a predefined hatch pattern, define your own hatch pattern, choose a solid color, or define a one- or two-color gradient fill.