The visual perceptional ability of computer systems to understand the environment is desirable in engineering design and manufacturing where automation is anticipated. I n order to empower a n engineering system with the heuristic capabilities, adequate knowledge representation techniques must be employed to resolve ambiguity in representation and uncertainty in decision making. Discussed in this paper is how to represent environmental knowledge as object models so that they can be utilized in spatial reasoning, and how to check knowledge completeness so that autonomous vision systems can be developed with self-regulated knowledge acquiring mechanism.