Comprehending parametric CAD models (original) (raw)
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Comprehending parametric CAD models: an evaluation of two graphical user interfaces
Proceedings of the 6th …, 2010
In this study, we experimentally evaluated two GUI prototypes (named "split" and "integrated") equivalent to those used in the domain of parametric CAD modeling. Participants in the study were asked to perform a number of 3D model comprehension tasks, using both interfaces. The tasks themselves were classified into three classes: parameterization, topological and geometrical tasks. We measured the task completion times, error rates, and user satisfaction for both interfaces. The experimental results showed that task completion times are significantly shorter when the "split" interface is used, in all cases of interest: 1) tasks taken as a whole and 2) tasks viewed by task type. There was no significant difference in error rates; however, error rate was significantly higher in the case of parameterization tasks for both interfaces. User satisfaction was significantly higher for the "split" interface. The study gave us a better understanding of the human performance when perceiving and comprehending parametric CAD models, and offered insight into the usability aspects of the two studied interfaces; we also believe that the knowledge obtained could be of practical utility to implementers of parametric CAD modeling packages.
User Interface Management System with Geometric Modeling Capability: A CAD System's Framework
IEEE Computer Graphics and Applications, 1985
Standardization of graphics program packages, beginning about 10 years ago and culminating as an international standard,1-4 was based on the assumption that modeling and drawing (viewing) should be separate. At that time the output pipeline, with windowing and graphical output primitives, was well understood. Today, in many experimental systems5-10 a geometric model can be visualized in different ways: as a wireframe, a color raster picture, or a realistic shaded image. Problems arose on the input side, however. The proposed input primitives were soon found to be much too primitive and to have no direct correspondence with the output primitive functions.11 Also it was realized that input actions often refer to the existing picture on the screen (the "pick" device), which of course must then be stored. This data structure, called segment storage, is essentially a model of the picture.
Interactive Programming for Parametric CAD
Computer Graphics Forum, 2020
Parametric computer‐aided design (CAD) enables description of a family of objects, wherein each valid combination of parameter values results in a different final form. Although Graphical User Interface (GUI)‐based CAD tools are significantly more popular, GUI operations do not carry a semantic description, and are therefore brittle with respect to changes in parameter values. Programmatic interfaces, on the other hand, are more robust due to an exact specification of how the operations are applied. However, programming is unintuitive and has a steep learning curve. In this work, we link the interactivity of GUI with the robustness of programming. Inspired by programme synthesis by example, our technique synthesizes code representative of selections made by users in a GUI interface. Through experiments, we demonstrate that our technique can synthesize relevant and robust sub‐programmes in a reasonable amount of time. A user study reveals that our interface offers significant improve...
International Journal of Technology and Design Education
In order to be reusable, history-based feature-based parametric CAD models must reliably allow for modifications while maintaining their original design intent. In this paper, we demonstrate that relations that fix the location of geometric entities relative to the reference system produce inflexible profiles that reduce model reusability. We present the results of an experiment where novice students and expert CAD users performed a series of modifications in different versions of the same 2D profile, each defined with an increasingly higher number of fix geometric constraints. Results show that the amount of fix constraints in a 2D profile correlates with the time required to complete reusability tasks, i.e., the higher the number of fix constraints in a 2D profile, the less flexible and adaptable the profile becomes to changes. In addition, a pilot software tool to automatically track this type of constraints was developed and tested. Results suggest that the detection of fix constraint overuse may result in a new metric to assess poor quality models with low reusability. The tool provides immediate feedback for preventing high semantic level quality errors, and assistance to CAD users. Finally, suggestions are introduced on how to convert fix constraints in 2D profiles into a negative metric of 3D model quality.
Understanding and Assisting CAD Users in the Real World
Proceedings of the 15th Annual Conference of the Association for Computer Aided Design in Architecture (ACADIA)
A former employee of the Intergraph Corporation, he is interested in improving the productivity of CAD systems by studying usability issues from an ethnographic as well as a cognitive perspective. His doctoral thesis involves the nature and prediction of CAD interaction errors.
Enabling diagnostics in user interfaces for CAD applications
2009
Computer aided design (CAD) applications such as Autodesk Civil 3D allow the user to specify design constraints for a number of common geometries. These applications typically prompt the user for the required constraints and then attempt to find a feasible solution. When there is no feasible solution, however, there is little or no explanation given to the user. Furthermore, given the number of degrees of freedom, it is unreasonable to expect the user to be able to analyze the solution space of the problem in order to correct his input. In this thesis I describe an extension to the geometric solvers in Civil 3D that will enable new user interfaces to assist the user in correcting his input. Furthermore I present several example user interfaces that demonstrate these new capabilities.
Developing a Parametric Approach for 3D Modelling Software
2006
The creation of 3D models is generally considered by newcomers to be a difficult activity requiring a number of skills and considerable practice. This paper describes work in the INHERIT project which aims to address these issues by providing a 3D modelling tool set which is easy to use, requiring few skills and little practice. This is achieved by the
CONCEPTUAL MODELING TOOL AT THE EARLY DESIGN PHASE
Although CAD systems have evolved considerably in functionality, expressiveness and modeling power over the last decades, their user interfaces are still tied to legacy principles and are not suited to the initial stages of product development. They exhibit steep learning curves, cumbersome and overly structured dialogues, including hundreds of commands. While much of this functionality may be required by the sheer complexity of the tasks these systems are designed to help, we believe the user interface could benefit from simpler paradigms based on sketching and drawing to reduce unneeded complexity, especially in the conceptual design phase. In what follows, we present the CIGRO system that provides a reduced instruction set calligraphic interface to create polyhedral objects using an incremental drawing paradigm evocative of paper and pencil drawings. Users sketch lines on an axonometric projection, which are automatically beautified and connected to existing parts of the drawing. Such line drawings are then converted to a three-dimensional model through a reconstruction process guided by an axonometric inflation method. While much work remains to be done, comparative usability evaluation tests conducted with expert and new users yielded very promising results.
Quest for Efficiency: Examining Cognitive Processes Underlying the Use of 3D Modeling Tools
eCAADe proceedings
In this paper we examine the strategies used in 3D modeling for their efficiency. Our study explores the underlying cognitive process that drives design thinking as well the choice of strategies for using specific features in a given CAD software. We take a cognitive task analysis approach to examine our question. Of a total sample of 19 participants, the strategies of the fastest and slowest users are compared to identify areas of improvement for software development as well as user training.
International Journal of Human-Computer Studies, 2010
This study proposes usability principles for the user interfaces (UI) design of complex 3D parametric architectural design and engineering tools. Numerous usability principles have been developed for generic desktop or web applications. The authors tried to apply existing usability principles as guidelines for evaluating complex 3D design and engineering applications. However, the principles were too generic and high-level to be useful as design or evaluation guidelines. The authors, all with more than 10 or 30 years of experience with various CAD systems, selected and reviewed 10 state-of-the-art 3D parametric design and engineering applications and captured what they thought were best practices, as screenshots and videos. The collected best practices were reviewed through a series of discussion sessions. During the discussion sessions, UI design principles underlying the collected best practices were characterized in the line of existing UI principles. Based on the best practices and the derived common UI principles, a new set of refined and detailed UI principles were proposed for improving and evaluating 3D parametric engineering design tools in the future.