Indoor Localization
Participated in improving indoor localization with Bluetooth Low Energy
(BLE) and Wi-Fi RTT beacons. Created map visualization to demonstrate the
quality of the localization and to find approaches for improvements.
Incorporated the technology into applications such as optimizing parts
deliveries in a factory.
Technical challenges. Fitted BLE path loss model and Wi-Fi RTT
distance measurements to ground truth. Implemented the particle filter
framework in C#, Java, and Python. Developed map visualizations in Xamarin and
Python Matplotlib. Conducted analyses with Numpy. Configured Wi-Fi RTT access
points for best performance.
Technologies. Xamarin, .NET, C#, Android, Java, Python, Numpy,
Matplotlib.
Fusing map information with sensor model
- A. Girgensohn, M. Patel, J. T. Biehl. Radio-Frequency-Based Indoor-Localization Techniques for Enhancing Internet-of-Things Applications, Personal and Ubiquitous Computing, Special Issue: Social Networks and Social Ubiquitous Computing, 2020.
- J. Biehl, A. Girgensohn, M. Patel. Achieving Accurate Room-Level Indoor Location Estimation With Emerging IoT Networks. International Conference on the Internet of Things (IoT), Article 4, 1-8, doi:10.1145/3365871.3365875, 2019.
- M. G. Jadidi, M. Patel, J. V. Miro, G. Dissanayake, J. Biehl, A. Girgensohn. A Radio-Inertial Localization and Tracking System With BLE Beacons Prior Maps. International Conference on Indoor Positioning and Indoor Navigation, 206-212, doi:10.1109/IPIN.2018.8533827, 2018.
- M. Patel, A. Girgensohn, J. Biehl. Fusing Map Information With a Probabilistic Sensor Model for Indoor Localization Using RF Beacons. International Conference on Indoor Positioning and Indoor Navigation, 1-8, doi:10.1109/IPIN.2018.8533758, 2018.
Video Surveillance
Created a video surveillance system that combined computer vision with
intuitive user interfaces. Provided access to many recorded or live video
streams to several clients in parallel. Used computer vision to locate people
in a map and across cameras.
Technical challenges. Recorded video from more than 20 cameras as
motion JPEG to support playback at variable speeds and in reverse. Handled
more than 1 TB of daily data. Devised a system to smoothly record and stream
that video. Designed and implemented a UI that provided access to the video as
synchronized playback for all cameras with higher frame rates for video in
focus. Used computer vision results provided by others to determine cameras of
interest and to track people on a map. Created a spatio-temporal analysis and
displayed it in the form of time-segmented heatmaps.
Technologies. Java (server and client), JPEG, REST.
Spatial arrangement of camera views
- E. Rieffel, A. Girgensohn, D. Kimber, T. Chen, Q. Liu. Geometric Tools for Multicamera Surveillance Systems. ICDSC, 132-139, doi:10.1109/ICDSC.2007.4357516, 2007.
- A. Girgensohn, D. Kimber, J. Vaughan, T. Yang, F. Shipman, T. Turner, E. Rieffel, L. Wilcox, F. Chen, T. Dunnigan. DOTS: Support for Effective Video Surveillance. ACM Multimedia, 423-432, doi:10.1145/1291233.1291332, 2007.
- D. Kimber, T. Dunnigan, A. Girgensohn, F. Shipman, T. Turner, T. Yang. Trailblazing: Video Playback Control by Direct Object Manipulation. ICME, 1015-1018, doi:10.1109/ICME.2007.4284825, 2007.
- A. Girgensohn, F. Shipman, T. Turner, L. Wilcox. Effects of Presenting Geographic Context on Tracking Activity Between Cameras. CHI, 1167-1176, doi:10.1145/1240624.1240801, 2007.
- A. Girgensohn, F. Shipman, T. Dunnigan, T. Turner, L. Wilcox. Support for Effective Use of Multiple Video Streams in Security. ACM International Workshop on Video Surveillance & Sensor Networks VSSN, 19-26, doi:10.1145/1178782.1178787, 2006.
- A. Girgensohn, F. Shipman, T. Turner, L. Wilcox. Video Surveillance: Keeping the Human in the Loop. UIST Companion, 2006.