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3D reconstruction and Auralisation of the "painted dolmen" of antelas
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... During archaeological excavations, total stations to measure local coordinates of single points There are two available different 3D scanning systems, according to literature: one is a laser scanner which records the surface via a laser pulse ( Bruno et al., 2010, Clarkson and Hiscock, 2011, Corns and Shaw, 2009, Kuzminsky and Gardiner, 2012, McCoy and Ladefoged, 2009, Robson Brown et al., 2001, Dias et al., 2008) the other is a structured light topometry which records the surface via reflection of a light pattern, while the associated software calculates 3D coordinates for each pixel of the image based on the triangulation principle ( Gilboa et al., 2013, Grosman et al., 2008, Güth, 2012, Karasik and Smilansky, 2008, McPherron et al., 2009, Niven et al., 2009, Pastoors and Weniger, 2011, Guidi, 2014). ...
The discovery of a Neolithic dolmen in Switzerland with inhumations, dating between 3500 and 3000 BCE, was an exceptional finding. To provide best conditions for subsequent studies on the archaeological remains our interdisciplinary team decided to apply 3D documentation. Depending on different factors, two scanning systems with four scanners and photogrammetry were applied and the obtained data was combined. Detailed excavation plans and simultaneously a reduction of excavation time without loss of information were the result. A virtual animation of the dolmen in its reconstructed ancient appearance combined with the context of the grave goods was created. The 3D documentation provided initial data for anthropological and paleogenetic analyses. The individuals buried in the dolmen might provide novel information to the Neolithic research of central Europe. Additionally, with the help of the 3D data, the dolmen was rebuilt to make this archaeological heritage accessible to the public.
... A demo from this project using a low-cost head-mounted display (HMD) system was awarded the first prize at the 2007 Audio Technology contest of the Portuguese section of the Audio Engineering Society (AES). An important potential application envisaged for this kind of systems was explored in [3]. ...
... A demo from this project using a low-cost head-mounted display (HMD) system was awarded the first prize at the 2007 Audio Technology contest of the Portuguese section of the Audio Engineering Society (AES). An important potential application envisaged for this kind of systems was explored in [3]. ...
This communication is an overview of the FCT-funded three-year research project ‘AcousticAVE – Auralisation Models and Applications in Virtual Reality Environments’, a collaboration between the Universities of Aveiro (UA - IEETA) and Minho (UM - CIPsi, LVP). The project involved the development of auralisation software based on the image-source method accommodating dynamic scenarios, with real-time tracking of source/listener motion and listener head orientation. This software supported psychophysical research at the CAVE-like facilities of UM’s Visualisation and Perception Lab (LVP). This included an investigation on learning effects in spatial audio perception using non-individualised HRTF sets and distance and time-to-passage (TTP) perception experiments.
... Additionally, though the equipment capable of producing 3D scans is commercially available, they are still very expensive and most are not eye safe nor indicated for navigation, but rather for scene reconstruction. Several authors have proposed configurations which produce 3D scans based on nodding or rotating existing 2D scanners [11][12][13][14]. In all published material, the angular velocity which is imposed on these 2D scanners has been considered low when compared to that of the internal mirror and therefore these have traditionally been considered as a sequence of 2D scans. ...
... Though Velodyne now produces the HDL-64, which is a robust and eye safe 3D laser, it is expensive (around €60k) and has 26.8º vertical field of view, which is relatively small for having simultaneous short and medium range perception needed in urban environments. Because a solution considered ideal to most researchers is still lacking, several research teams have proposed that a 2D range-finder may be converted at low cost into 3D with wide field of view [19] [20][21] [22][23] [24]. The Laboratory for Automation and Robotics at the University of Aveiro has developed its own prototype solution for 3D range finding [21] [25], in the form of a spinning forward looking 2D SICK as seen in Fig. 7. ...
The future of intelligent vehicles will rely on robust information to allow the proper feedback to the vehicle itself, to issue several kinds of active safety, but before all, to generate information for the driver by calling his or her attention to potential instantaneous or mid-term risks associated with the driving. Before true vehicle autonomy, safety and driver assistance are a priority. Sophisticated sensorial and perceptive mechanisms must be made available for, in a first instance, assisting the driver and, on a latter phase, participate in better autonomy. These mechanisms rely on sensors and algorithms that are mostly available nowadays, but many of them are still unsuited for critical situations. This paper presents a project where engineering and scientific solutions have been devised to settle a full featured real scale platform for the next generation of ITS vehicles that are concerned with the immediate issues of navigation and challenges on the road. The car is now ready and running, and the data gathering has just begun.
Computer-aided methods are used extensively to analyze archaeological images. This data can then be used to make mappings and provide greater structural understanding of archaeological objects of interest. This paper details a numerical analysis of a typical Korean dolmen, performed in order to enhance our understanding of its structure in terms of force/pressure, strain/stress, and fatigue damage. The advanced engineering tools “ABAQUS” and “Nastran” are employed to analyze force/pressure, deformation/strain/stress relations, and the overall distribution of stress and damage, respectively. This structural analysis was performed for various geometrical configurations such as offset distances of the top stone, inclined angles of the supporting stones, and varying shapes of dolmens. This analysis shows that dolmens having vertically-erected supporting stones are most stable. With the help of this parametric study using idealized models, two real existing models were applied to analyze and predict damage to the table-type dolmens. The accuracy of the numerical predictions shows that this kind of analysis has great potential to be the method of choice for structural understanding of such objects. If run in parallel with the sensing techniques currently used, it could greatly aid in the conservation of archaeological objects.
Rudimentary acoustical measurements performed inside six diverse ancient structures revealed that each sustained a strong resonance at a frequency between 95 and 120 Hz, despite major differences in chamber shapes and sizes. The resonant modal patterns all featured strong antinodes at the outer walls, with appropriately configured nodes and antinodes interspersed toward the central source. In some cases, interior and exterior rock drawings resembled these acoustical patterns. Since the resonance frequencies are well within the adult male voice range, one may speculate that some forms of human chanting, enhanced by the cavity resonance, were invoked for ritual purposes. (C) 1996 Acoustical Society of America.
The following paper presents the first results obtained in a recently growing-up Digital Signal Processing branch: the reconstruction of temporal and spatial characteristics of the sound field in a concert hall, starting from monophonic anechoic (dry) digital music recordings, and applying FIR filtering to obtain binaural (stereo) tracks. The FIR filters employed in this work are experimentally derived binaural impulse responses, obtained from a correlation process between the signal emitted through a loudspeaker on the stage of the theatre and the signals received through two binaural microphones, placed at the ear channel entrance of a dummy head. The convolution process has been implemented by two different algorithm: time domain true convolution and frequency domain select-save; both runs on the CM-2 computer, and the second also on any Unix machine. The results of the convolution process have been compared by direct headphone listening with binaural recordings of the same music pieces, emitted through a loudspeaker in the same theatres, and recorded through the dummy head connected to a DAT digital recorder.
This paper reviews 3D sound technology. It focuses on the core technical issue of 3D sound: the scientific and engineering means by which a listener of a stereo reproduction system can perceive the direction of a sound in a 3D space. The scientific basis is first discussed, followed by the practical techniques for 3D stereo reproduction.
The theory and techniques for virtual acoustic modeling and rendering are discussed. The creation of natural sounding audiovisual environments can be divided into three main tasks: sound source, room acoustics, and listener modeling. These topics are discussed in the context of both non-real-time and real-time virtual acoustic environments. Implementation strategies are considered, and a modular and expandable simulation software is described.
Ivan Sutherland first proposed virtual reality in 1965, and in the next few years built a working system. Twenty years later, line-drawing hardware, the Polhemus tracker, and LCD tiny-TV displays made VR feasible, if costly and inadequate, for several explorers. In 1990, journalists jumped on the idea, and hype levels went out of sight. As usual with infant technologies, the realization of the early dreams and the harnessing to real work has taken longer than the wild prognostications, but it is now happening. I survey the current state-of-the-art, addressing the perennial questions of technology and applications.
Artificial reverberator topologies making use of all-pass filters in a feedback loop are popular, but have lacked accurate control of decay time and energy level. This paper reviews a general theory of artificial reverberators based on Unitary-Feedback Delay Networks (UFDN), which allow accurate control of the decay time at multiple frequencies in such topologies. We describe the design of an efficient reverberator making use of chains of elementary filters, called "absorbent all-pass filters", in a feedback loop. We show how, in this particular topology, the late reverberant energy level can be controlled independently of the other control parameters. This reverberator uses the I3DL2 control parameters, which have been designed as a standard interface for controlling reverberators in interactive 3D audio.
This article provides a snapshot of immersive virtual reality (IVR) use for scientific visualization, in the context of the evolution of computing in general and of user interfaces in particular. The main thesis of this article is that IVR has great potential for dealing with the serious problem of exponentially growing scientific datasets. Our ability to produce large datasets both through numerical simulation and through data acquisition via sensors is outrunning our ability to make sense of those datasets. While our idea of “large” datasets used to be measured in hundreds of gigabytes, based at least in part on what we could easily store, manipulate, and display in real time, today's science and engineering are producing terabytes and soon even petabytes, both from observation via sensors and as output from numerical simulation. Clearly, visualization by itself will not solve the problem of understanding truly large datasets that would overwhelm both display capacity and the human visual system. We advocate a human–computer partnership that draws on the strengths of each partner, with algorithmic culling and feature-detection used to identify the small fraction of the data that should be visually examined in detail by the human. Our hope is that IVR will be a potent tool to let humans “see” patterns, trends, and anomalies in their data well beyond what they can do with conventional 3D desktop displays.
How virtual reality is helping improve patient care in the form of advanced educational tools and therapeutic options.
This article presents a 3D reconstruction technique for real world environments based on a traditional 2D laser range finder modified to implement a 3D laser scanner. The article describes the mechanical and control issues addressed to physically achieve the 3D sensor used to acquire the data. It also presents the techniques used to process and merge range and intensity data to create textured polygonal models and illustrates the potential of such a unit. The result is a promising system for 3D modeling of real world scenes at a commercial price 10 or 20 times lower than current commercial 3D laser scanners. The use of such a system can simplify measurements of existing buildings and produce easily 3D models and ortophotos of existing structures with minimum effort and at an affordable price.
This paper describes a general purpose, representation independent
method for the accurate and computationally efficient registration of
3-D shapes including free-form curves and surfaces. The method handles
the full six-degrees of freedom and is based on the iterative closest
point (ICP) algorithm, which requires only a procedure to find the
closest point on a geometric entity to a given point. The ICP algorithm
always converges monotonically to the nearest local minimum of a
mean-square distance metric, and experience shows that the rate of
convergence is rapid during the first few iterations. Therefore, given
an adequate set of initial rotations and translations for a particular
class of objects with a certain level of 'shape complexity', one can
globally minimize the mean-square distance metric over all six degrees
of freedom by testing each initial registration. For examples, a given
'model' shape and a sensed 'data' shape that represents a major portion
of the model shape can be registered in minutes by testing one initial
translation and a relatively small set of rotations to allow for the
given level of model complexity. One important application of this
method is to register sensed data from unfixtured rigid objects with an
ideal geometric model prior to shape inspection. The described method is
also useful for deciding fundamental issues such as the congruence
(shape equivalence) of different geometric representations as well as
for estimating the motion between point sets where the correspondences
are not known. Experimental results show the capabilities of the
registration algorithm on point sets, curves, and surfaces.