Abstract. The recognition of symbols in graphic documents is an intensive research activity in the community of pattern recognition and document analysis. A key issue in the interpretation of maps, engineering drawings, diagrams, etc. is the recognition of domain dependent symbols according to a symbol database. In this work we first review the most outstanding symbol recognition methods from two different points of view: application domains and pattern recognition methods. In the second part of the paper, open and unaddressed problems involved in symbol recognition are described, analyzing their current state of art and discussing future research challenges. Thus, issues such as symbol representation, matching, segmentation, learning, scalability of recognition methods and performance evaluation are addressed in this work. Finally, we discuss the perspectives of symbol recognition concerning to new paradigms such as user interfaces in handheld computers or document database and WWW indexing by graphical content.
ABSTRACT:Sound planning is not often included in the urban design process despite the well-known audio-visual interactions of human perception. A methodology to compare the overall appreciation of future renovation alternatives of urban public spaces using Virtual Reality Technology is proposed. This method is applied to assess the role of noise in the overall appreciation of a walk on a bridge crossing a highway. The auralization is a dynamic 3D surround based on B-format recordings (ambisonics), filtered by means of full-wave numerical calculations obtaining the sound field behind noise barriers along the bridge's edge. Four different styles of visual street design including different noise barrier heights in combination with the 4 corresponding predicted sound fields were evaluated for their pleasantness by 71 normal-hearing participants on 4 separate days. Each day participants experienced all the visual environments with only one soundscape (to elude direct sound comparison) and anything related to sound was not mentioned in the first part of the experiment. Even in this non-focussed context, a statistically significant effect of the sound environment on the overall appreciation was found. In general, the pleasantness increases with traffic noise level reduction, but the visual design has a stronger impact. By mentioning the soundscape while introducing the evaluation, slightly lower (but statistically significantly different) pleasantness ratings were obtained. Instead of increasing noise barrier height, improving the visual design of a lower barrier seems more effective to increase pleasantness.Visual designs including vegetation strongly outperform others. The virtual experience was rated as immersive and realistic.3
Abating road traffic noise pollution is one of the main urban environmental challenges nowadays.However, architects and urbanists take decisions on urban regulations that define the shape of streets and buildings without taking this aspect into account. Furthermore, there is little information about the influence of urban geometry on traffic noise exposure in streets. In this study, the effect of street canyon design on sound pressure level distribution is numerically studied in high detail with the full-wave finite-difference time-domain method (FDTD). The CNOSSOS equivalent source power spectra were used to approach road traffic noise sources along two traffic lanes. Receivers both along the façades and the sidewalks have been considered in 42 cases. Numerical results demonstrate that building shape, street geometry and the presence of street furniture can have a strong impact on people's noise exposure. Building shape can be responsible for variations of up to 7.0dB(A) at pedestrians. Building-façade design can reduce the average exposure at windows with 12.9dB(A). It was further predicted that street geometry can enhance the positive effect of low barriers to 11.3dB(A) along sidewalks. It was therefore concluded that carefully designing building façades and street geometry could improve the sound climate for people living and walking along busy urban streets and should be considered in future urban street design.
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