Julián Conesa

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.

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.

An Agent-Based Paradigm for Free-Hand Sketch Recognition

Natural interfaces for CAD applications based on sketching devices have been explored to some extent. Former approaches used techniques to perform the recognition process like invariant features extracted with image analysis techniques as neural networks, statistical learning or fuzzy logic. Currently, more flexible and robust techniques are being introduced, which consider other information as context data and other relationships. However, this kind of interfaces is still scarcely extended because they still lack scalability and reliability for interpreting user inputs.

Smart sketch system for 3D reconstruction based modeling

Current user interfaces of CAD systems are still not suited to the initial stages of product development, where freehand drawings are used by engineers and designers to express their visual thinking. In order to exploit these sketching skills, we present a sketch based modeling system, which provides a reduced instruction set calligraphic interface to create orthogonal polyhedra, and an extension of them we named quasi-normalons. Our system allows users to draw lines on free-hand axonometric-like drawings, which are automatically tidied and beautified. These line drawings are then converted into a threedimensional model in real time because we implemented a fast reconstruction process, suited for quasi-normalon objects and so-called axonometric inflation method, providing in this way an innovative integrated 2D sketching and 3D view visualization work environment.

A new agent-based paradigm for recognition of free-hand sketches

Abstract Currently, important advances are carried out in CAD (Computer Aided Design) applications; however these advances have not taken place for CAS (Computer Aided Sketching) applications. Although natural interfaces for CAD applications are not solved yet, works based on sketching devices have been explored to some extent. The recognition paradigm we propose using an agentbased architecture does not depend on the drawing sequence and takes context information into account to help decisions. An improvement provided is the absence of operation modes, that is, no button is needed to distinguish geometry from symbols or gestures, and also “interspersing” and “overtracing” is accomplished.