A method for deforming a solid and avoiding the creation of self-intersecting solid structures in a topography simulator. In a topography simulated based on a solids modeling system, self-intersecting structures are solids which have boundaries that intersect. Such self-intersecting structures are invalid and cannot be processed. A general method for sweeping a solid surface to create a deformed solid and avoid the creation of self-intersecting solid structures is described, which include the steps of: providing a material solid with a surface represented as one or more segments; constructing a first segment solid for a first segment; performing a boolean set operation between the solid being swept and the first segment solid creating a temporary first solid; identifying a second segment; constructing a second segment solid for the second segment; and performing the boolean set operation between said temporary first solid and said first segment solid creating said deformed first solid. The case where simultaneous deposition and etch is occurring requires utilizes separate temporary deposition and etch solids for each segment both of which are swept to create the deformed solid.