Design Evaluator is a freehand drawing environment that incorporates critiquing into a freehand sketch design system for early design. Design Evaluator's main features include a sketch interface, critiquing, and visualization of critiquing results. The system interprets the floor plan and provides critiques of three types when it finds conflicts between the sketched floor plan and built-in rules; text message, annotated drawing and 3D model/walk-through.