Surface hatches are hatch patterns on three-dimensional (3D) objects that display in 3D model views and elevation views.
Each 3D object has a number of faces: Top, Bottom, Left, Right, Front, and Back. You can decide whether an object should carry a surface hatch. For example, if you view a wall in 3D view, you might want to hatch only the side facing you to avoid cluttering the drawing.
The faces of an object that carry the surface hatch are specified in the material definition. All objects with that material definition assigned show the same surface hatch assignment, unless you create an individual surface hatch override.
Defining the faces on a regular object, such as a wall, slab, or box-shaped mass element, is intuitive. Front, Back, Left, Right, Top and Bottom are clearly defined faces that can easily be assigned material definitions. However, defining the direction in which each face lies can be more complex for different, irregularly shaped objects, such as curved objects, extrusion objects, or Free Form objects resulting from Boolean operations.
Specifying object face material assignments