Error classification and recovery within CAD model reconstruction

Abstract

With ever increasing demands from international markets and responding industries for a quick transfer as well as processing of CAD and product data between different computer aided applications, within as well as between a product's life cycle stages, activities dedicated to the development and standardization of data representations and exchange formats are more critical than ever before. However, in practice, before complete standards and developed models and systems succeed and become reality, interim solutions are required to bridge certain gaps. One application field, requiring such interim solutions until robust methods are found, to correct error causing processes, is the exchange and consequent repair of geometric models. Due to subtle errors in geometric models and their representations, caused by design mistakes, programming errors or model evaluation failures, irrational behavior of CAD systems and other, post design related systems exchanging as well as accessing CAD data, are becoming a frequently observed situation, causing a severe break in the process of computer aided product development. To recover from such a rather undesirable situation, we propose an interim solution, aimed at bridging the gap between generation of corrupted CAD data and model exchanging post design applications. An approach, that is based on an error classification driven systematic recovery of corrupted CAD data being subject to model reconstruction. The approach taken includes a classification scheme for face adjacency errors, missing faces and curve adjacency errors for which dedicated individual methods and solutions were developed and related to. Practical work used to support as well as provide parameters for validation and assessment of proposed solutions was carried out using an implemented testbed, which is based on spatial model point distance tolerances driven face sewing. During experimental work exchange format used for model import/export were limited to IGES. Investigated models imported through these standardized data exchange formats were mainly taken from mechanical engineering.