Differential Conversion: DWG – SVG Case Study

Abstract

This paper is focused on differential conversion, which is a new approach to data transformation between different software systems. The strategy of differential conversion, which is built on a log of changes and identifier mapping, was introduced in CDVE 2006 in a purely theoretical paper entitled Data Exchange in CAD during Iterative Work with Heterogeneous Systems. A specific case study of differential conversion in use is elaborated in this text. It is about an intelligent bi-directional transformation between DWG and SVG. DWG is a proprietary CAD-format of the AutoCAD system, whereas SVG is an open, generic graphics format, based on XML. The implemented transformation allows usage of a model created in a CAD-system within a cooperative design intended for non-CAD users. It is useful not only for reading, but even for writing into the model and modifying it. Any changes made are returned back to the original model. The following case exemplifies the previously discussed strategy. For example, a project submitter, or another party in the review process, can use a normal, generic SVG editor for writing comments and proposals into the model. A solver can transform them back into the CAD-model, without other entities in the model being damaged. This case study describes differential export and import tools and takes note of the particular solutions of the log of changes and identifier mapping problems. It also describes the relationship to the original differential conversion proposal, discusses the particular implementation, and again generalizes into some design pattern for differential conversion implementation projects in the conclusion.