A Multi-Threaded Fast Convolver for Dynamically Parallel Image Filtering

2D convolution is a staple of digital image processing. The advent of large format imagers makes it possible to literally ``pave'' with silicon the focal plane of an optical sensor, which results in very large images that can require a significant amount computation to process. Filtering of large images via 2D convolutions is often complicated by a variety of effects (e.g., non-uniformities found in wide field of view instruments). This paper describes a fast (FFT based) method for convolving images, which is also well suited to very large images. A parallel version of the method is implemented using a multi-threaded approach, which allows more efficient load balancing and a simpler software architecture. The method has been implemented within in a high level interpreted language (IDL), while also exploiting open standards vector libraries (VSIPL) and open standards parallel directives (OpenMP). The parallel approach and software architecture are generally applicable to a variety of algorithms and has the advantage of enabling users to obtain the convenience of an easy operating environment while also delivering high performance using a fully portable code.Comment: 25 pages including color figures. Submitted to the Journal of Parallel and Distributed Computin

MatlabMPI

The true costs of high performance computing are currently dominated by software. Addressing these costs requires shifting to high productivity languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI currently implements the basic six functions that are the core of the MPI point-to-point communications standard. The key technical innovation of MatlabMPI is that it implements the widely used MPI ``look and feel'' on top of standard Matlab file I/O, resulting in an extremely compact (~250 lines of code) and ``pure'' implementation which runs anywhere Matlab runs, and on any heterogeneous combination of computers. The performance has been tested on both shared and distributed memory parallel computers (e.g. Sun, SGI, HP, IBM, Linux and MacOSX). MatlabMPI can match the bandwidth of C based MPI at large message sizes. A test image filtering application using MatlabMPI achieved a speedup of ~300 using 304 CPUs and ~15% of the theoretical peak (450 Gigaflops) on an IBM SP2 at the Maui High Performance Computing Center. In addition, this entire parallel benchmark application was implemented in 70 software-lines-of-code, illustrating the high productivity of this approach. MatlabMPI is available for download on the web (www.ll.mit.edu/MatlabMPI).Comment: Download software from http://www.ll.mit.edu/MatlabMPI, 12 pages including 7 color figures; submitted to the Journal of Parallel and Distributed Computin

Extending physical instruments using sampled acoustics

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2007.Includes bibliographical references (p. 133-138).This thesis presents a system architecture for creating hybrid digital-acoustic percussion instruments by combining extensions of existing signal processing techniques with specially-designed semi-acoustic physical controllers. This work aims to provide greater realism to digital percussion, gaining much of the richness and understandability of acoustic instruments while preserving the flexibility of digital systems. For this thesis, I have collaborated with percussionists to develop a range of instruments, to refine and extend the algorithmic and physical designs, and to determine successful models of interaction. Conventional percussion controllers measure and discretize the intensity of strikes into discrete trigger messages, but they also ignore the timbre of the hits and fail to track more ambiguous input. In this work, the continuous acoustic output of a struck physical object is processed to add the resonance of a sampled instrument. This is achieved by employing existing low-latency convolution algorithms which have been extended to give the player control over features such as damping, spectral flattening, nonlinear effects, and pitch.(cont.) One of the advantages of this approach is that light taps, scrapes, rubs, or stirring with brushes all take on a hybrid timbre of the real and sampled sound that is surprisingly realistic and controllable. Since part of its behavior is inherently acoustic, a player's intuition about interacting with physical objects can be applied to controlling it. The ability to transform the apparent acoustic properties of objects also suggests applications to HCI and product design contexts.by Roberto Mario Aimi.Ph.D

Aspects of room acoustics, vision and motion in the human auditory perception of space

The human sense of hearing contributes to the awareness of where sound-generating objects are located in space and of the environment in which the hearing individual is located. This auditory perception of space interacts in complex ways with our other senses, can be both disrupted and enhanced by sound reflections, and includes safety mechanisms which have evolved to protect our lives, but can also mislead us. This dissertation explores some selected topics from this wide subject area, mostly by testing the abilities and subjective judgments of human listeners in virtual environments. Reverberation is the gradually decaying persistence of sounds in an enclosed space which results from repeated sound reflections at surfaces. The first experiment (Chapter 2) compared how strongly people perceived reverberation in different visual situations: when they could see the room and the source which generated the sound; when they could see some room and some sound source, but the image did not match what they heard; and when they could not see anything at all. There were no indications that the visual image had any influence on this aspect of room-acoustical perception. The potential benefits of motion for judging the distance of sound sources were the focus of the second study (Chapter 3), which consists of two parts. In the first part, loudspeakers were placed at different depths in front of sitting listeners who, on command, had to either remain still or move their upper bodies sideways. This experiment demonstrated that humans can exploit motion parallax (the effect that closer objects appear faster to a moving observer than farther objects) with their ears and not just with their eyes. The second part combined a virtualisation of such sound sources with a motion platform to show that the listeners’ interpretation of this auditory motion parallax was better when they performed this lateral movement by themselves, rather than when they were moved by the apparatus or were not actually in motion at all. Two more experiments were concerned with the perception of sounds which are perceived as becoming louder over time. These have been called “looming”, as the source of such a sound might be on a collision course. One of the studies (Chapter 4) showed that western diamondback rattlesnakes (Crotalus atrox) increase the vibration speed of their rattle in response to the approach of a threatening object. It also demonstrated that human listeners perceive (virtual) snakes which engage in this behaviour as especially close, causing them to keep a greater margin of safety than they would otherwise. The other study (section 5.6) was concerned with the well-known looming bias of the sound localisation system, a phenomenon which leads to a sometimes exaggerated, sometimes more accurate perception of approaching compared to receding sounds. It attempted to find out whether this bias is affected by whether listeners hear such sounds in a virtual enclosed space or in an environment with no sound reflections. While the results were inconclusive, this experiment is noteworthy as a proof of concept: It was the first study to make use of a new real-time room-acoustical simulation system, liveRAZR, which was developed as part of this dissertation (Chapter 5). Finally, while humans have been more often studied for their unique abilities to communicate with each other and bats for their extraordinary capacity to locate objects by sound, this dissertation turns this setting of priorities on its head with the last paper (Chapter 6): Based on recordings of six pale spear-nosed bats (Phyllostomus discolor), it is a survey of the identifiably distinct vocalisations observed in their social interactions, along with a description of the different situations in which they typically occur.Das menschliche Gehör trägt zum Bewusstsein dafür bei, wo sich schallerzeugende Objekte im Raum befinden und wie die Umgebung beschaffen ist, in der sich eine Person aufhält. Diese auditorische Raumwahrnehmung interagiert auf komplexe Art und Weise mit unseren anderen Sinnen, kann von Schallreflektionen sowohl profitieren als auch durch sie behindert werden, und besitzt Mechanismen welche evolutionär entstanden sind, um unser Leben zu schützen, uns aber auch irreführen können. Diese Dissertation befasst sich mit einigen ausgewählten Themen aus diesem weiten Feld und stützt sich dabei meist auf die Testung von Wahrnehmungsfähigkeiten und subjektiver Einschätzungen menschlicher Hörer/-innen in virtueller Realität. Beim ersten Experiment (Kapitel 2) handelte es sich um einen Vergleich zwischen der Wahrnehmung von Nachhall, dem durch wiederholte Reflexionen an Oberflächen hervorgerufenen, sukzessiv abschwellenden Verbleib von Schall in einem umschlossenen Raum, unter verschiedenen visuellen Umständen: wenn die Versuchsperson den Raum und die Schallquelle sehen konnte; wenn sie irgendeinen Raum und irgendeine Schallquelle sehen konnte, dieses Bild aber vom Schalleindruck abwich; und wenn sie gar kein Bild sehen konnte. Dieser Versuch konnte keinen Einfluss eines Seheindrucks auf diesen Aspekt der raumakustischen Wahrnehmung zu Tage fördern. Mögliche Vorteile von Bewegung für die Einschätzung der Entfernung von Schallquellen waren der Schwerpunkt der zweiten Studie (Kapitel 3). Diese bestand aus zwei Teilen, wovon der erste zeigte, dass Hörer/-innen, die ihren Oberkörper relativ zu zwei in unterschiedlichen Abständen vor ihnen aufgestellten Lautsprechern auf Kommando entweder stillhalten oder seitlich bewegen mussten, im letzteren Falle von der Bewegungsparallaxe (dem Effekt, dass sich der nähere Lautsprecher relativ zum sich bewegenden Körper schneller bewegte als der weiter entfernte) profitieren konnten. Der zweite Teil kombinierte eine Simulation solcher Schallquellen mit einer Bewegungsplattform, wodurch gezeigt werden konnte, dass die bewusste Eigenbewegung für die Versuchspersonen hilfreicher war, als durch die Plattform bewegt zu werden oder gar nicht wirklich in Bewegung zu sein. Zwei weitere Versuche gingen auf die Wahrnehmung von Schallen ein, deren Ursprungsort sich nach und nach näher an den/die Hörer/-in heranbewegte. Derartige Schalle werden auch als „looming“ („anbahnend“) bezeichnet, da eine solche Annäherung bei bedrohlichen Signalen nichts Gutes ahnen lässt. Einer dieser Versuche (Kapitel 4) zeigte zunächst, dass Texas-Klapperschlangen (Crotalus atrox) die Vibrationsgeschwindigkeit der Schwanzrassel steigern, wenn sich ein bedrohliches Objekt ihnen nähert. Menschliche Hörer/-innen nahmen (virtuelle) Schlangen, die dieses Verhalten aufweisen, als besonders nahe wahr und hielten einen größeren Sicherheitsabstand ein, als sie es sonst tun würden. Der andere Versuch (Abschnitt 5.6) versuchte festzustellen, ob die wohlbekannte Neigung unserer Schallwahrnehmung, näherkommende Schalle manchmal übertrieben und manchmal genauer einzuschätzen als sich entfernende, durch Schallreflektionen beeinflusst werden kann. Diese Ergebnisse waren unschlüssig, jedoch bestand die Besonderheit dieses Versuchs darin, dass er erstmals ein neues Echtzeitsystem zur Raumakustiksimulation (liveRAZR) nutzte, welches als Teil dieser Dissertation entwickelt wurde (Kapitel 5). Abschließend (Kapitel 6) wird die Schwerpunktsetzung auf den Kopf gestellt, nach der Menschen öfter auf ihre einmaligen Fähigkeiten zur Kommunikation miteinander untersucht werden und Fledermäuse öfter auf ihre außergewöhnliches Geschick, Objekte durch Schall zu orten: Anhand von Aufnahmen von sechs Kleinen Lanzennasen (Phyllostomus discolor) fasst das Kapitel die klar voneinander unterscheidbaren Laute zusammen, die diese Tiere im sozialen Umgang miteinander produzieren, und beschreibt, in welchen Situationen diese Lauttypen typischerweise auftreten

NASA Tech Briefs, Winter 1985

Topics covered include: NASA TU Services; New Product Ideas; Electronic Components and Circuits;Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences

A Model-based Design Framework for Application-specific Heterogeneous Systems

The increasing heterogeneity of computing systems enables higher performance and power efficiency. However, these improvements come at the cost of increasing the overall complexity of designing such systems. These complexities include constructing implementations for various types of processors, setting up and configuring communication protocols, and efficiently scheduling the computational work. The process for developing such systems is iterative and time consuming, with no well-defined performance goal. Current performance estimation approaches use source code implementations that require experienced developers and time to produce. We present a framework to aid in the design of heterogeneous systems and the performance tuning of applications. Our framework supports system construction: integrating custom hardware accelerators with existing cores into processors, integrating processors into cohesive systems, and mapping computations to processors to achieve overall application performance and efficient hardware usage. It also facilitates effective design space exploration using processor models (for both existing and future processors) that do not require source code implementations to estimate performance. We evaluate our framework using a variety of applications and implement them in systems ranging from low power embedded systems-on-chip (SoC) to high performance systems consisting of commercial-off-the-shelf (COTS) components. We show how the design process is improved, reducing the number of design iterations and unnecessary source code development ultimately leading to higher performing efficient systems

Index to 1985 NASA Tech Briefs, volume 10, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1985 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Development of a software for panoramic video and audio recordings with microphone arrays

Dense microphones array is certainly one of the most promising technology not only for environmental noise analysis, but also for 3D audio recordings, where 3D stands for a complete spatial description of the event recorded. During last years at the Industrial Engineering Department of Università degli Studi di Parma (IED) with the collaboration of the spinoff AIDA srl., a new meta-theory was developed that provides a framework capable of representing all the known microphones array, based on the model of Virtual Microphones. The strict collaboration with the Centro Ricerca ed Innovazione Tecnologica (CRIT, Research Center and Technology Innovation) of RAI, the national Italian television broadcasting company, quickly individuates some key applications of this technology that conduct to the realization of some ad-hoc dense arrays and of a software to manage all the acquisition and post-processing system. In this PhD thesis work a detailed description of the software, named 3D VMS, will be given, preceded by an introduction about the current state of the art of this technology.Sviluppo di array planari di microfoni e dell'HW/SW necessario per un'applicazione alla manutenzione predittiva delle macchin