Dr. Daniel O'Keefe Profile

Dr. Daniel O'Keefe

at US Air Force Academy

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Author

Publications (3)

Proceedings Article | 3 October 2023 Presentation + Paper

Event-based camera refractory period characterization and initial clock drift evaluation

Peter McMahon-Crabtree, Lucas Kulesza, Brian McReynolds, Daniel O'Keefe, Anirvin Puttur, Diana Maestas, Christian Morath, Matthew McHarg

Proceedings Volume 12693, 126930V (2023) https://doi.org/10.1117/12.2672301

KEYWORDS: Cameras, Clocks, Sensors, Commercial off the shelf technology, Integrating spheres, Light sources, Monte Carlo methods, Light emitting diodes, Modulation, Visualization

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Event-based camera (EBC) technology provides high-dynamic range operation and shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors, etc.). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate the development of new characterization techniques and sensor models to evaluate hardware performance and elucidate the trade-space between the two camera architectures. Laboratory characterization techniques reported previously include noise level as a function of static scene light level (background activity) and contrast responses referred to as S-curves. Here we present further progress on development of basic characterization methods and test capabilities for commercial-off-the-shelf (COTS) visible EBCs, with a focus on measurement of pixel deadtime (refractory period) including results for the 4th-generation sensor from Prophesee and Sony. Refractory period is empirically determined from analysis of the interspike intervals (ISIs), and results visualized using log-histograms of the minimum per-pixel ISI values for a subset of pixels activated by a controlled dynamic scene. Our tests of the Prophesee gen4 EVKv2 yield refractory period estimates ranging from 6.1 msec to 6.8 μsec going from the slowest (20) to fastest (100) settings of the relevant bias parameter, bias_refr. We also introduce and demonstrate the concept of pixel bandwidth measurement from data captured while viewing a static scene – based on recording data at a range of refractory period setting and then analyzing noise-event statistics. Finally, we present initial results for estimating and correcting EBC clock drift using a GPS PPS signal to generate special timing events in the event-list data streams generated by the DAVIS346 and DVXplorer EBCs from iniVation.

Proceedings Article | 3 October 2023 Presentation + Paper

Modeling and decoding event-based sensor lightning response

Brian McReynolds, Rui Graca, Daniel O'Keefe, Rachel Oliver, Richard Balthazor, Nathaniel George, Matthew McHarg

Proceedings Volume 12693, 1269313 (2023) https://doi.org/10.1117/12.2674435

KEYWORDS: Sensors, Cameras, Light sources and illumination, Lightning, Transistors, Photocurrent, Modeling, Performance modeling, Statistical modeling, Simulations

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Proceedings Article | 4 October 2022 Presentation + Paper

Experimental validation of model-based digital holographic imaging using multi-shot data

Timothy Bate, Daniel O'Keefe, Mark Spencer, Casey Pellizzari

Proceedings Volume 12239, 122390D (2022) https://doi.org/10.1117/12.2633499

KEYWORDS: Digital holography, Turbulence, Data modeling, Reflectivity, Expectation maximization algorithms, Speckle, Algorithm development, Holograms, Reconstruction algorithms, Model-based design

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