Understanding and Supporting Debugging Workflows in CAD

One of the core promises of parametric Computer-Aided Design (CAD) is that users can easily edit their model at any point in time. However, due to the ambiguity of changing references to intermediate, updated geometry, parametric edits can lead to reference errors which are difficult to fix in practice. We claim that debugging reference errors remains challenging because CAD systems do not provide users with tools to understand where the error happened and how to fix it. To address these challenges, we prototype a graphical debugging tool, DeCAD, which helps comparing CAD model states both across operations and across edits. In a qualitative lab study, we use DeCAD as a probe to understand specific challenges that users face and what workflows they employ to overcome them. We conclude with design implications for future debugging tool developers.