Manuel Contero

Improving visualization skills in engineering education

This article analyzes the importance of visualization skills in engineering education. It proposes a dual approach based on computer graphics applications using both Web-based graphic applications ...

Technical Section: An optimisation-based reconstruction engine for 3D modelling by sketching

An engine that automatically reconstructs a large variety of polyhedral, origami and wire-frame objects from single-view sketched drawings generated in a calligraphic interface is presented. The engine has two stages. An innovative optimisation-based line-drawing beautifier stage is introduced to convert rough sketches into tidied-up line drawings. Optimisation-based 3D reconstruction follows. Solutions are provided with which to overcome the problems associated with earlier approaches to optimisation-based 3D reconstruction. Suitable adjustments in the optimisation algorithms are proposed; simple and efficient tentative models are introduced, and current regularities are categorised in order to allow the objective function to be simplified. All three actions help to prevent local optima and improve the computational efficiency of optimisation-based 3D reconstruction. They all proved to be effective techniques to reduce the typical failure rate of optimisation approaches. A discussion of results that validate the engine is also provided.

Computer-aided sketching as a tool to promote innovation in the new product development process

Sketching is an established part of engineering culture. Sketches assist product designers during the creative stages of design and help them to develop inventions. Paper-and-pencil sketching is highly useful but lacks functionalities, mainly because it is disconnected from the rest of the (computer-aided) design process. However, CAS tools are not yet as usable as paper-and-pencil, although they provide full integration with the subsequent phases of the design processes (CAD, CAE, CAM, etc.) and other interesting functionalities. We desire computer-aided sketching (CAS) tools which furnish users with the sketching environment they require to make full use of their conceptual design and innovation talents, while providing full integration with the subsequent phases of the design processes (CAD, CAE, CAM, etc.). In this paper we discuss the importance of sketching in conceptual design, we review the current situation of engineering sketching, and we then analyze the main characteristics which a successful and fully integrated CAS tool should include. We consider CAS, not as a single problem, but as at least three: thinking, prescriptive and talking sketches require different approaches to functionality. Finally, we present the current state of the art in CAS tools by describing the main features and outstanding problems of our own applications.

Product data quality and collaborative engineering

We survey the impact of product data quality within an extended enterprise framework and present a linguistic model, which focuses on three levels: morphological, syntactic, and semantic.

On the evolution of geometrical reconstruction as a core technology to sketch-based modeling

In this work, the background and evolution of three-dimensional reconstruction of line drawing over the last thirty years is discussed. A new general taxonomy is proposed to describe and discuss the historical evolution of geometrical reconstruction and its challenges. The evolution of geometrical reconstruction from recovering know-how stored in engineering drawings to sketch-based modeling for helping in the first steps of conceptual design purposes, and the current challenges of geometrical reconstruction are also discussed.

Evaluating the usability of an augmented reality based educational application

Technological developments and changes mean that computer-based teaching tools rapidly become obsolete or less attractive to students. In teaching, as in other fields, there is a continual need to explore new technologies that are attractive, adapted to the personal needs of students and which motivate them to learn. Students are struck by the appearance of new technology or gadgets and they show an interest in using them. This paper analyses the potential of Augmented Reality technology in university education. An AR-based application has been developed with a view to improving spatial abilities among engineering students, thus enabling them to gain a better understanding of engineering graphics subjects. We present a student satisfaction study and an evaluation of the efficiency and efficacy of the technology applied to this field of education.

CIGRO: a minimal instruction set calligraphic interface for sketch-based modeling

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, cumber-some 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 draw lines using an axonometric projection, which are automatically beautified and connected to existing elements of the drawing. Such line drawings are then converted to a three-dimensional model through a reconstruction process guided by an axonometric inflation method.

Extended 3D annotations as a new mechanism to explicitly communicate geometric design intent and increase CAD model reusability

Abstract A successful implementation of the Model-Based Enterprise concept (MBE) requires maximizing the potential benefits of annotated 3D models. The foundations of the MBE model are established by digital product definition data practices, which are currently regulated by standards such as ASME Y14.41-2003 and ISO 16792:2006. At the center of the MBE concept is the notion of CAD model reusability, which relies on the idea that 3D CAD models can be reused both throughout the entire product lifecycle and as a starting point for future development of new products. In this context, a critical aspect of CAD model reuse is the proper identification and understanding of the geometric design intent that is usually expressed implicitly within the CAD model. In this work, we present a method to communicate geometric design intent explicitly by overloading and extending the scope of the current annotation instruments available in the MBE approach. We propose a new broader type of model annotation that we call “extended annotation”, where design information is represented both internally within the 3D model and externally, on a separate repository. This structure naturally demands additional mechanisms to support the interaction of users with the information. In order to manage the information stored in these extended annotations effectively, we implemented an annotation manager that automatically synchronizes the dual representation of the annotations. To reduce the visual clutter in the 3D model, the software provides powerful filtering, editing, and visualization capabilities, giving users complete control of the information stored in the model. Finally, a study was conducted with 60 participants to evaluate the performance of the proposed model and the usability of the annotation manager. Results show a statistically significant benefit of using the extended annotation system, suggesting the use of this model as a valuable approach to improve design intent communication.

Parametric CAD modeling

CAD model quality in parametric design scenarios largely determines the level of flexibility and adaptability of a 3D model (how easy it is to alter the geometry) as well as its reusability (the ability to use existing geometry in other contexts and applications). In the context of mechanical CAD systems, the nature of the feature-based parametric modeling paradigm, which is based on parent-child interdependencies between features, allows a wide selection of approaches for creating a specific model. Despite the virtually unlimited range of possible strategies for modeling a part, only a small number of them can guarantee an appropriate internal structure which results in a truly reusable CAD model. In this paper, we present an analysis of formal CAD modeling strategies and best practices for history-based parametric design: Delphis horizontal modeling, explicit reference modeling, and resilient modeling. Aspects considered in our study include the rationale to avoid the creation of unnecessary feature interdependencies, the sequence and selection criteria for those features, and the effects of parent/child relations on model alteration. We provide a comparative evaluation of these strategies in the form of a series of experiments using three industrial CAD models with different levels of complexity. We analyze the internal structure of the models and compare their robustness and flexibility when the geometry is modified. The results reveal significant advantages of formal modeling methodologies, particularly resilient techniques, over non-structured approaches as well as the unexpected problems of the horizontal strategy in numerous modeling situations. We analyze three formal CAD modeling strategies for history-based parametric design.User performance was studied using three industrial CAD models with different levels of complexity.Formal modeling methodologies offer significant advantages over non-structured approaches.Modeling methodologies significantly affect reusability.

Dynamic three‐dimensional illustrator for teaching descriptive geometry and training visualisation skills

This article presents a pilot study with architecture students, in which the effects of descriptive geometry, taught conventionally and using a three‐dimensional dynamic tool designed for the purpose, on the improvement of spatial abilities are compared and analysed. In relation with previous works, the main contribution of this research is the development of a three‐dimensional viewer (Diedro‐3D) to support the teaching process, encouraging autonomous learning. The Diedro‐3D application tries to overcome the main obstacle that student face when using a descriptive geometry textbook: static 2D illustrations of high complexity. This is achieved by providing a series of construction steps and supporting a 3D visualisation environment where the student can freely change the point of view. It is important to note that students show a high degree of satisfaction with the learning experience using Diedro‐3D as usability analysis confirms.