Advances in technology coupled with the availability of low-cost sensors have resulted in the continuous generation of large time series from several sources. In order to visually explore and compare these time series at different scales, analysts need to execute online analytical processing (OLAP) queries that include constraints and group-by's at multiple temporal hierarchies. Effective visual analysis requires these queries to be interactive. However, while existing OLAP cube-based structures can support interactive query rates, the exponential memory requirement to materialize the data cube is often unsuitable for large data sets. Moreover, none of the recent space-efficient cube data structures allow for updates. Thus, the cube must be re-computed whenever there is new data, making them impractical in a streaming scenario. We propose Time Lattice, a memory‐efficient data structure that makes use of the implicit temporal hierarchy to enable interactive OLAP queries over large time series. Time Lattice is a subset of a fully materialized cube and is designed to handle fast updates and streaming data. We perform an experimental evaluation which shows that the space efficiency of the data structure does not hamper its performance when compared to the state of the art. In collaboration with signal processing and acoustics research scientists, we use the Time Lattice data structure to design the Noise Profiler, a web-based visualization framework that supports the analysis of noise from cities. We demonstrate the utility of Noise Profiler through a set of case studies.

For example, we used the Noise Profiler to rapidly explore and visualize noise patterns in NYC during weekdays versus weekends across multiple locations, using time series data from SONYC noise sensors:

For further details see our paper:

Time Lattice: A Data Structure for the Interactive Visual Analysis of Large Time Series
F. Miranda, M. Lage, H. Doraiswamy, C. Mydlarz, J. Salamon, Y. Lockerman, J. Freire, C. Silva
Computer Graphics Forum (EuroVis '18), 37(3), 2018, 13-22
[Wiley][PDF][BibTeX]

Today SONYC was featured on several major news outlets including the New York Times, NPR and Wired! This follows NYU's press release about the official launch of the SONYC project.

Needless to say I'm thrilled about the coverage the project's launch is receiving. Hopefully it is a sign of the great things yet to come from this project, though, I should note, it has already resulted in several scientific publications.

Here's the complete list of media articles (that I could find) covering SONYC. The WNYC radio segment includes a few words from yours truly :)

BBC World Service - World Update (first minute, then from 36:21)

Sounds of New York City (German Public Radio)

Over the past two years I've been working together with a fantastic team of researchers on the SONYC: Sounds of New York City project. Check out our new video!

The objectives of SONYC are to create technological solutions for: (1) the systematic, constant monitoring of noise pollution at city scale; (2) the accurate description of acoustic environments in terms of its composing sources; (3) broadening citizen participation in noise reporting and mitigation; and (4) enabling city agencies to take effective, information-driven action for noise mitigation.

Noise pollution is one of the topmost quality of life issues for urban residents in the United States. It has been estimated that 9 out of 10 adults in New York City (NYC) are exposed to excessive noise levels, i.e. beyond the limit of what the EPA considers to be harmful. When applied to U.S. cities of more than 4 million inhabitants, such estimates extend to over 72 million urban residents.

To learn more about the SONYC project please check out the project website: wp.nyu.edu/sonyc

To read our publications on automatic urban sound classification as well as the development of low-cost, high-quality acoustic sensors, check out the project's publication page: wp.nyu.edu/sonyc/publications