Algorithmic Perception of Vertices in Sketched Drawings of Polyhedral Shapes

In this article, visual perception principles were used to build an artificial perception model aimed at developing an algorithm for detecting junctions in line drawings of polyhedral objects that are vectorized from hand-drawn sketches. The detection is performed in two dimensions (2D), before any 3D model is available and minimal information about the shape depicted by the sketch is used. The goal of this approach is to not only detect junctions in careful sketches created by skilled engineers and designers but also detect junctions when skilled people draw casually to quickly convey rough ideas. Current approaches for extracting junctions from digital images are mostly incomplete, as they simply merge endpoints that are near each other, thus ignoring the fact that different vertices may be represented by different (but close) junctions and that the endpoints of lines that depict edges that share a common vertex may not necessarily be close to each other, particularly in quickly sketched drawings. We describe and validate a new algorithm that uses these perceptual findings to merge tips of line segments into 2D junctions that are assumed to depict 3D vertices

Particle Swarm Optimisation Based 3D Reconstruction of Sketched Line Drawings

The purpose of this paper is to demonstrate the application of particle swarm optimisation to line drawings reconstruction. The paper’s new contribution is the application of swarm intelligence in dealing with machine perception of sketch-based modelling interfaces. Traditional descent or gradient- based optimisation algorithms are not always practical in this context because of the severe numerical noise and ill-defined objective function of the optimisation-based reconstruction problem Our results point to particle swarm optimisation as a promising alternative.This work was partially supported by Universitat Jaume I (Plan 2002 de promoció de la investigació a l’UJI, Project P1-1B2002-08, entitled “From sketch to model: new user interfaces for CAD systems”)

A method for reconstructing sketched polyhedral shapes with rounds and fillets

In this paper we present a method for detecting rounds and fillets in engineering sketches and drawings, and automatically generating a 3D model of the corresponding object, with rounds and fillets applied. This method is useful both as a component of computer-aided sketching tools and in determining de- sign intent—although rounds and fillets are common in engineering parts, they often conceal design intent, which is more easily determined from the object’s underlying polyhedral skeleton

Integrated modeling with Top-Down approach in subsidiary industries

This article considers how conceptual design of industrial products is supported by current CAD systems. The case of subsidiary industries, or first tier suppliers, that must simultaneously deal with different customers and CAD platforms, receive special attention. Conceptual design is critical, since the large variety of fundamental product data managed (not just geometry) would be specified, modeled and interrelated (i.e. functional relations), to both simplify and ensure correctness and efficiency of the next design phases of current design, and make them easy to reuse, modify and redesign in the future. We give an approach to introduce conceptual design through top-down methodology and integrate it with final geometry. In this context, and in order to help subsidiary industries to improve their model quality, we propose the elaboration of product-oriented modeling guidelines, or “best modeling practices”, instead of CAD-oriented modeling guidelines. The approach has been validated by testing the conceptual design tools of two commercial high-end CAD systems at use in many subsidiary automotive industries

Lossless equalization of frequency combs

Frequency combs obtained by sinusoidal phase modulation of narrow-band continuous-wave lasers are widely used in the field of optical communications. However, the resulting spectral envelope of the comb is not at. In this Letter, we propose a general and eficient approach to achieve at frequency combs with tunable bandwidth. The idea is based on a two-step process. First, eficient generation of a train with temporal at-top-pulse profile is required. Second, we use large parabolic phase modulation in every train period in order to map the temporal intensity shape into the spectral domain. In this way, the resulting spectral envelope is at and the size is tunable with the chirping rate. Two diferent schemes are proposed and verified through numerical simulations

Parametric CAD modeling: An analysis of strategies for design reusability

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: Delphi's 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. (C)2016 Elsevier Ltd. All rights reserved.Camba, JD.; Contero, M.; Company, P. (2016). Parametric CAD modeling: An analysis of strategies for design reusability. Computer-Aided Design. 74:18-31. doi:10.1016/j.cad.2016.01.003S18317

A unified approach to describe optical pulse generation by propagation of periodically phase-modulated CW laser light

The analysis of optical pulse generation by phase modulation of narrowband continuous-wave light, and subsequent propagation through a group-delay-dispersion circuit, is usually performed in terms of the so-called bunching parameter. This heuristic approach does not provide theoretical support for the electrooptic flat-top-pulse generation reported recently. Here, we perform a waveform synthesis in terms of the Fresnel images of the periodically phase-modulated input light. In particular, we demonstrate flat-top-pulse generation with a duty ratio of 50% at a quarter of the Talbot condition for the sinusoidal phase modulation. Finally, we propose a binary modulation format to generate a well-defined square-wave-type optical bit pattern.Comment: 10 pages, 5 figures. Submitted to Optics Expres

Perception and Demands of Pregnant and Breastfeeding Women Regarding Their Role as Participants in Environmental Research Studies

A significant proportion of scientific studies consider pregnant and breastfeeding women as vulnerable subjects. The objective of this study was to analyse the perception of pregnant and breastfeeding women regarding their participation in environmental research studies. Our work is a descriptive and interpretative observational study that has been developed under the qualitative research paradigm following a phenomenological and ethnographic perspective. The study involved 173 women selected intentionally in two Spanish autonomous communities. To obtain the primary data, we relied upon 111 interviews, four focused ethnographies and eight focus groups. The data encoding and analysis was carried out with the help of NVivo 12 software (QSR International, Boston, MA, USA). We evidenced the need of pregnant and breastfeeding women for more detailed and accurate information on the risk of environmental pollutant exposure during their crucial life stage. In addition, these women claimed for a more participatory role in research studies. Pregnant and breastfeeding women in Spain ask for greater interaction with researchers and propose a dialogical relationship between valid partners. We conclude that our pregnant and breastfeeding women claim more research focused on their collective, as well as clearer, more accessible and structured information on the risks of exposure to environmental contaminants. In addition, they do not want to simply be informants; rather, they ask to be active and empowered members by providing their opinions and arguments throughout the research process.Fundación Pública Andaluza Progreso y Salud de la Junta de Andalucía, Spain (reference: AP-0139-2017)Ministry of Health of the Junta de Andalucía, Spain - A-0043-2018Ramón y Cajal programme (RYC-2016-20155, of the Ministry of Economy, Industry and Competitiveness, Spain)

Perimeter detection in sketched drawings of polyhedral shapes

Ponència presentada al STAG17: Smart tools and Applications in Graphics, celebrat a Catania (Itàlia) 11-12 setembre 2017This paper describes a new “envelope” approach for detecting object perimeters in line-drawings vectorised from sketches of polyhedral objects. Existing approaches for extracting contours from digital images are unsuitable for Sketch-Based Modelling, as they calculate where the contour is, but not which elements of the line-drawing belong to it. In our approach, the perimeter is described in terms of lines and junctions (including intersections and T-junctions) of the original line drawing

A fast approach for perceptually-based fitting strokes into elliptical arcs

Fitting elliptical arcs to strokes of an input sketch is discussed. We describe an approach which automatically combines existing algorithms to get a balance of speed and precision. For measuring precision, we introduce fast metrics which are based on perceptual criteria and are tolerant of sketching imperfections. We return a likelihood estimate based on these metrics rather than deterministic yes/no result, in order that the approach can be used in higher-level collaborative-decision recognition flows.1) Ramon y Cajal Scholarship Programme 2) "Pla de Promoció de la Investigació de la Universitat Jaume I", project P1 1B2010-0