Papers by Sergio Freire Garcia

Anais do XVIII Simpósio Brasileiro de Computação Musical (SBCM 2021)
Pierre Schaeffers typomorphology (1966) proposes seven criteria of musical perception for the qua... more Pierre Schaeffers typomorphology (1966) proposes seven criteria of musical perception for the qualification of sound objects, which form the basis of his musical theory. This Solfège fits well into contexts where pitch is not the dominant dimension. Relying on similarities between the practice of reduced listening and the utilization of low-level audio descriptors, we present the first version of a real-time setup in which these descriptors are applied to qualify percussive sounds. The paper describes the tools and strategies used for addressing different criteria: envelope followers with different window sizes and filtering; detection of transients and amplitude modulations; extraction and counting of spectral components; estimation of intrinsic dissonance and spectral distribution; among others. The extracted data is subjected to simple statistical analysis, producing scalar values associated with each segmented object. Finally, we present a variety of examples.

A crônica de Kurt Weill, “Possibilidades da radioarte absoluta”, escrita em 1925, aborda uma séri... more A crônica de Kurt Weill, “Possibilidades da radioarte absoluta”, escrita em 1925, aborda uma série de questões ligadas ao uso e às influências de novas tecnologias na criação artística, mais especificamente aquelas relacionadas ao possível desenvolvimento de um novo gênero musical puramente auditivo já na primeira metade do século XX. As especulações de Weill, fruto da grande efervescência cultural existente no período entreguerras alemão até a ascensão do nazismo, trazem contribuições valiosas para o estudo de uma “pré-história” da música eletroacústica. Temas como a invisibilidade do meio, a ampliação da paleta sonora, o processamento de sons e o fim do estrelismo são ali abordados, ao lado de questões mais gerais, ligadas às relações entre arte e técnica, arte e política, cinema e radioarte. Encontra-se em anexo uma tradução dessa crônica para o português, autorizada pela Fundação Kurt Weill para a Música, de Nova York.Kurt Weill’s "Possibilities of Absolute Radio Art",...

The high rate of changes in cities requires the existence of matching geographic information in o... more The high rate of changes in cities requires the existence of matching geographic information in order to enable proper land monitoring and planning. When cartographic information exists, but is outdated , a change detection procedure using recent geographic data can be applied for map updating. The aim of such an analysis is to highlight those areas where changes have most likely occurred. The goal of this work is to present an object-oriented methodology that enables outdated large-scale cartography to be updated, using Very-High Resolution (VHR) imagery and Light Detection and Ranging (Lidar) data. The procedure is a two-step method. The remote sensing data is used to map the present land cover situation, and then, based on a change/no-change approach the land information is used for updating the large-scale cartography. The result is an alarm system that indicates the location of potential changes in the built-up zones. However, in order to be a legally valid document, the mapped...

Proceedings of the SMC Conferences, Jul 30, 2013
This paper presents an experimental setup for the study of right hand techniques on the acoustic ... more This paper presents an experimental setup for the study of right hand techniques on the acoustic guitar, and describes the main features of our apparatus regarding the extraction of audio descriptors. A preliminary case study on the tremolo technique is also discussed, where four different musicians played five versions of the same musical excerpt. These versions are compared on the basis of the regularity of the rhythmic pattern, the note durations, and the uniformity of the amplitudes. The comparison results suggest a direct relationship between rhythmic regularity and the player's level of expertise. Nevertheless, this relationship does not apply to the note durations or the dynamic regularity. Finally, some concerns regarding the difficulties in listening to the discovered (ir)regularities are addressed, and some steps for further research are pointed out.
Proceedings of the SMC Conferences, Jul 26, 2015
The paper presents a set of mid-level descriptors for the analysis of musical textures played on ... more The paper presents a set of mid-level descriptors for the analysis of musical textures played on the guitar, divided in six categories: global, guitar-specific, rhythm, pitch, amplitude and spectrum descriptors. The employed system is based on an acoustic fretted nylon string guitar with hexaphonic pick-ups, and was programmed in Max. An overview of the explored low-level audio descriptors is given in the first section. Mid-level descriptors, many of them based on a general affordance of the guitar, are the subject of the central section. Finally, some distinctive characteristics of five different textures -two-voice writing, block chords, arpeggios, fast gestures with legato, slow melody with accompaniment-are highlighted with the help of the implemented tools.
The increasing availability of accessible sensor technologies, single board computers, and protot... more The increasing availability of accessible sensor technologies, single board computers, and prototyping platforms have resulted in a growing number of frameworks explicitly geared towards the design and construction of Digital and Augmented Musical Instruments. Developing such instruments can be facilitated by choosing the most suitable framework for each project. In the process of selecting a framework for implementing an augmented guitar instrument, we have tested three Linux-based open-source platforms that have been designed for real-time sensor interfacing, audio processing, and synthesis. Factors such as acquisition latency, workload measurements, documentation, and software implementation are compared and discussed to determine the suitability of each environment for our particular project.
Proceedings of the SMC Conferences, Jul 4, 2018
The paper presents an exploratory study about the guitar strumming technique, based on three diff... more The paper presents an exploratory study about the guitar strumming technique, based on three different accompaniment patterns. The experiments were held with an acoustic nylon guitar equipped with hexaphonic pickups, and focused on different features of this technique. It was possible to note a diversity of strategies for beat control and rhythmic expression employed by different musicians, which may be described by technical, perceptive and expressive factors. The results also display preliminary quantitative boundaries for the distinction between block, strummed and arpeggio chords.

Sustainability, 2021
This review analyses peer-reviewed scientific publications and policy documents that use built-up... more This review analyses peer-reviewed scientific publications and policy documents that use built-up density, population density and settlement typology spatial grids from the Global Human Settlement Layer (GHSL) project to quantify human presence and processes for sustainability. Such open and free grids provide detailed time series spanning 1975–2015 developed with consistent approaches. Improving our knowledge of cities and settlements by measuring their size extent, as well as the societal processes occurring within settlements, is key to understanding their impact on the local, regional and global environment for addressing global sustainability and the integrity of planet Earth. The reviewed papers are grouped around five main topics: Quantifying human presence; assessing settlement growth over time; estimating societal impact, assessing natural hazard risk and impact, and generating indicators for international framework agreements and policy documents. This review calls for con...
GHS built-up grid, derived from Landsat, multitemporal (1975, 1990, 2000, 2014)

Open Forum Infectious Diseases, 2021
Background The Brazilian Football Confederation (CBF) protocol to control the spread of COVID-19 ... more Background The Brazilian Football Confederation (CBF) protocol to control the spread of COVID-19 among professional soccer players is based on four cornerstone measures: (1) Tracing all symptomatic and asymptomatic COVID-19 cases by clinical monitoring and nasal swab SARS-CoV-2 RT-PCR testing up to 3 days before the soccer games; (2) Respiratory isolation of all SARS-CoV-2 positive players for at least 10 days, regardless symptoms; (3) All player with clinical suspicion of COVID-19 were immediately quarantined; (4) If a player became SARS-CoV-2 positive after the game, the other players were allowed to play the next game, if they remained asymptomatic and SARS-CoV-2 RT-PCR negative. Understanding how antibody responses to SARS-CoV-2 evolve can provide insights into therapeutic and testing approaches for COVID-19. In the present study we profile the antibody responses of players up to nine months from a SARS-CoV-2 positive RT-PCR test. Methods Serum samples were obtained from 955 soc...
Os grãos da voz e do espaço: escutando objetos sonoros de Schaeffer nas salas de Lucier
O espaco pode transformar um objeto sonoro? Este estudo tem por objetivo discutir as influencias ... more O espaco pode transformar um objeto sonoro? Este estudo tem por objetivo discutir as influencias do espaco na estrutura intrinseca do material sonoro, segundo os criterios tipo- morfologicos de Pierre Schaeffer. Os ambientes escolhidos para o trabalho provem de duas gravacoes da peca I’m Sitting in a Room, de Alvin Lucier. Ao final do trabalho, sao apontadas as transformacoes sofridas pelos objetos sonoros - que nao raro perdem sua identidade inicial neste processo - atraves da acao desses espacos e quais os criterios utilizados para descreve-las.
Audio Processing by Means of FM Synthesis Parameters: Fundamentals, Real-Time Implementation, and Preliminary Compositional Applications

In recent years we have observed an incredible increase in location-specific information provided... more In recent years we have observed an incredible increase in location-specific information provided voluntarily by individuals and disseminated via the internet. The emergence of this Volunteered Geographic Information (VGI) as Goodchild first described it in 2007 [1] has attracted considerable interest within the GIScience research community. As a special type of user generated content, it offers great potential to produce up-to-date and near real-time information related to any place on Earth, even though overall accuracy remains an issue of debate. Location sharing services (LSS) such as ‘foursquare’, ‘Gowalla’, and ‘Facebook Places’ collect hundreds of millions of user-driven footprints or ‘check-ins’. Those footprints provide a unique opportunity to (1) study social and temporal characteristics of how people use these services and (2) model patterns of human mobility. However, the amount and frequency of VGI is not evenly distributed and recent research considers it directly rela...
This paper describes two augmented nylon-string guitar projects developed in different institutio... more This paper describes two augmented nylon-string guitar projects developed in different institutions. GuitarAMI uses sensors to modify the classical guitars constraints while GuiaRT uses digital signal processing to create virtual guitarists that interact with the performer in real-time. After a bibliographic review of Augmented Musical Instruments (AMIs) based on guitars, we present the details of the two projects and compare them using an adapted dimensional space representation. Highlighting the complementarity and cross-influences between the projects, we propose avenues for future collaborative work.
We consider the estimation problem of misspecified ergodic Lévy driven stochastic differential eq... more We consider the estimation problem of misspecified ergodic Lévy driven stochastic differential equation models based on high-frequency samples. We utilize a widely applicable and tractable Gaussian quasi-likelihood approach which focuses on mean and variance structure. It is shown that the Gaussian quasi-likelihood estimators of the drift and scale parameters still satisfy polynomial type probability estimates and asymptotic normality at the same rate as the correctly specified case. In their derivation process, the theory of extended Poisson equation for time-homogeneous Feller Markov processes plays an important role. Our result confirms the reliability of the Gaussian quasi-likelihood approach for SDE models.

Sensors, 2020
Computing technologies have opened up a myriad of possibilities for expanding the sonic capabilit... more Computing technologies have opened up a myriad of possibilities for expanding the sonic capabilities of acoustic musical instruments. Musicians nowadays employ a variety of rather inexpensive, wireless sensor-based systems to obtain refined control of interactive musical performances in actual musical situations like live music concerts. It is essential though to clearly understand the capabilities and limitations of such acquisition systems and their potential influence on high-level control of musical processes. In this study, we evaluate one such system composed of an inertial sensor (MetaMotionR) and a hexaphonic nylon guitar for capturing strumming gestures. To characterize this system, we compared it with a high-end commercial motion capture system (Qualisys) typically used in the controlled environments of research laboratories, in two complementary tasks: comparisons of rotational and translational data. For the rotations, we were able to compare our results with those that ...

Nature Communications, 2020
The knowledge of the spatial and temporal distribution of human population is vital for the study... more The knowledge of the spatial and temporal distribution of human population is vital for the study of cities, disaster risk management or planning of infrastructure. However, information on the distribution of population is often based on place-of-residence statistics from official sources, thus ignoring the changing population densities resulting from human mobility. Existing assessments of spatio-temporal population are limited in their detail and geographical coverage, and the promising mobile-phone records are hindered by issues concerning availability and consistency. Here, we present a multi-layered dasymetric approach that combines official statistics with geospatial data from emerging sources to produce and validate a European Union-wide dataset of population grids taking into account intraday and monthly population variations at 1 km2 resolution. The results reproduce and systematically quantify known insights concerning the spatio-temporal population density structure of la...

Global Ecology and Conservation, 2020
Protected areas (PAs) are a key strategy in global efforts to conserve biodiversity and ecosystem... more Protected areas (PAs) are a key strategy in global efforts to conserve biodiversity and ecosystem services that are critical for human well-being. Most PAs have some built-up structures within their boundaries or in surrounding areas, ranging from individual buildings to villages, towns and cities. These structures, and the associated human activities, can exert direct and indirect pressures on PAs. Here we present the first global analysis of current patterns and observed long-term trends in built-up areas within terrestrial PAs and their immediate surroundings. We calculate for each PA larger than 5 km 2 and for its 10-km unprotected buffer zone the percentage of land area covered by built-up areas in 1975, 1990, 2000 and 2014. We find that globally built-up areas cover only 0.12% of PA extent and a much higher 2.71% of the unprotected buffers as of 2014, compared to 0.6% of all land (protected or unprotected). Built-up extent in and around PAs is highest in Europe and Asia, and lowest in Africa and Oceania. Built-up area percentage is higher in coastal and small PAs, and lower in older PAs and in PAs with stricter management categories. From 1975 to 2014, the increase in built-up area was 23 times larger in the 10-km unprotected buffers than within PAs. Our findings show that the development of built-up structures remains limited within the boundaries of PAs but highlight the need to carefully manage the considerable pressure that PAs face from their immediate surroundings.
Revista Música Hodie, 2018
The paper presents a real-time tool for the segmentation and analysis of body gestures, part of a... more The paper presents a real-time tool for the segmentation and analysis of body gestures, part of a larger setup for exploring music and dance in the contexts of electroacoustic composition, live-electronics and other interactive performances. The idea of gesture is the foundation of the proposed interactive strategies, and is discussed from different points of view. The current implementation uses the Max/Msp programming language and Kinect sensors. The segmentation of dance gestures is based on the inspection of the zero-crossings of the acceleration curve of each body joint. Concepts from Laban Movement Analysis are used to qualify the extracted gestures. Dance improvisations on Petrushka excerpts are the basis of a case study, where the relations between the music (tempo, pulses, instrumentation, character) and Laban Basic Actions are stressed.

International Journal of Digital Earth, 2019
Geo-information on settlements from Earth Observation offers a base for objective and scalable mo... more Geo-information on settlements from Earth Observation offers a base for objective and scalable monitoring of the evolution of cities and settlements, including their location, extent and other attributes. In this work, we deploy the best available global knowledge on the presence of human settlements and built-up structures derived from Earth Observation to advance the understanding of the human presence on Earth. We start from a concept of Generalised Settlement Area to identify the Earth surface within which any built-up structure is present. We further characterise the resulted map by using an agreement map among the state of the art of remote sensing products mapping built-up areas or other strictly related semantic abstractions as urban areas or artificial surfaces. The agreement map is formed by a grid of 1 km 2 , where each cell is classified according to the number of EO-derived products reporting any positive occurrence of the abstractions related to the presence of built-up structures. The paper describes the characteristics of the Generalised Settlement Area, the differences in the agreement map across geographic regions of the world, and outlines the implications for potential users of the EO-derived products used in this study.
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Papers by Sergio Freire Garcia