This thesis concerns about how feedback integrates into a sketch design system. Design Feedback as critiques can help the designer better envisage what a design will be like in advance, allowing the designer to avoid certain kinds of errors. This thesis discusses how a freehand sketch critiquing system can be developed and how this tool can support in the architectural design process as design tool.

The thesis proposes a working prototype, Design Evaluator to demonstrate the potential of this knowledge-based design system. The Design Evaluator system has the design knowledge translated into rules related to four architectural spatial issues: proper room sequence, adjacency, room placement, and minimum area.

The Design Evaluator interprets the designer's architectural diagram and recognizes the spatial relations such as circulation paths and room placements. It checks the architectural diagram with the built-in rules. When a rule violation occurs, the system displays the design critiques in three ways: text messages, annotated drawings, and texture-mapped 3D visualization. These critiques stimulate the designer's "reflection-in-action" cycle during the sketching of her/his design ideas. Moreover, they help the designer to detect errors in the early design stage.

Design Evaluator: Sketch-based Interface with design critiques