Dr. Peter N. McMahon-Crabtree Profile

Dr. Peter N. McMahon-Crabtree

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Author

Publications (18)

Proceedings Article | 18 June 2024 Presentation + Paper

Re-interpreting the step-response probability curve to extract fundamental physical parameters of event-based vision sensors

Brian McReynolds, Rui Graca, Lucas Kulesza, Peter McMahon-Crabtree

Proceedings Volume 12996, 129960M (2024) https://doi.org/10.1117/12.3022308

KEYWORDS: Light sources and illumination, Dark current, Pulse signals, Sensors, Interference (communication), Photocurrent, Logic, Linear filtering, Information visualization, Contour extraction

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Biologically inspired event-based vision sensors (EVS) are growing in popularity due to performance benefits including ultra-low power consumption, high dynamic range, data sparsity, and fast temporal response. They efficiently encode dynamic information from a visual scene through pixels that respond autonomously and asynchronously when the per-pixel illumination level changes by a user-selectable contrast threshold ratio, θ. Due to their unique sensing paradigm and complex analog pixel circuitry, characterizing Event-based Vision Sensor (EVS) is non-trivial. The step-response probability curve (S-curve) is a key measurement technique that has emerged as the standard for measuring θ. Though the general concept is straightforward, obtaining accurate results requires a thorough understanding of pixel circuitry and non-idealities to correctly obtain and interpret results. Furthermore, the precise measurement procedure has not been standardized across the field, and resulting parameter estimates depend strongly on methodology, measurement conditions, and biasing – which are not generally discussed. In this work, we detail the method for generating accurate S-curves by applying an appropriate stimulus and sensor configuration to decouple 2nd-order effects from the parameter being studied. We use an EVS pixel simulation to demonstrate how noise and other physical constraints can lead to error in the measurement, and develop two techniques that are robust enough to obtain accurate estimates. We then apply best practices derived from our simulation to generate S-curves for the latest generation Sony IMX636 and interpret the resulting family of curves to correct the apparent anomalous result of previous reports suggesting that θ changes with illumination. Further, we demonstrate that with correct interpretation, fundamental physical parameters such as dark current and RMS noise can be accurately inferred from a collection of S-curves, leading to more accurate parameterization for high-fidelity EVS simulations.

Proceedings Article | 6 June 2024 Presentation + Paper

Shadow imagery resolution advantages from multispectral image stacking

Douglas Ruyle, David Curtis, Peter McMahon-Crabtree

Proceedings Volume 13062, 130620A (2024) https://doi.org/10.1117/12.3012879

KEYWORDS: Diffraction, Satellites, Image restoration, Shadows, Stars, Telescopes, Image resolution, Reconstruction algorithms, MATLAB, Cameras

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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 | 30 September 2022 Presentation + Paper

Automated characterization techniques and testbeds for event-based cameras

Peter McMahon-Crabtree, Wellesley Pereira, Robert Crow, Richard Preston, Lucas Kulesza, Ryan Crowell, Christian Morath, Diana Maestas, Zachry Theis, Patricia Sablan

Proceedings Volume 12233, 122330B (2022) https://doi.org/10.1117/12.2634166

KEYWORDS: Sensors, Cameras, Reliability, Gamma radiation, Aerospace engineering, Optical testing, Ionizing radiation effects

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Event-based camera (EBC) technology 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). 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 development of new characterization techniques to quantify performance and assess if the EBC technology produces benefits relative to traditional imaging sensors. Here we present progress on development of basic sensor performance modeling and test capabilities for commercial-off-the-shelf visible EBCs. Laboratory characterization techniques include noise level as a function of static scene light level (termed background activity) and EBC temporal contrast response to dynamic signals. Initial environmental tests of the Prophesee PPS3MVCD event-based sensor found several addressable areas of concern but identified no showstoppers that would prevent use of this device in a high-reliability aerospace application. Two independent radiation tolerance test efforts, one for the PPS3MVCD and another for the iniVation DAVIS346 EBC (both based on 180 nm CMOS technology), indicate functional issues for total ionizing dose (TID) of greater than 30 krad(Si), and show background activity increasing with TID. However, no significant change in contrast response was observed. One DAVIS346 exhibited functional failure following final gamma radiation dose from 20 krad(Si) to 50 krad(Si), and the readout saturated during doses dominated by negative-polarity events (by a factor of 10 or greater). A second DAVIS346 locked-up during proton dose but recovered normal operation following a brief rest period and power cycling. DAVIS346 pixels include both change detection (DVS) and standard grayscale frames (APS) functionalities – driven by a single photodiode; results show a 70% increase in dark current and 23% increase in dark event noise after proton exposure to 20 krad(Si). As new versions of EBC technology are developed for infrared wavelengths, we anticipate these characterization techniques will be largely translatable to IR EBCs.

Proceedings Article | 18 September 2014 Paper

Spectral method for calculating pixel overlap areas applied to multiframe image de-aliasing

Edward Cohen, Richard Picard, Peter Crabtree

Proceedings Volume 9227, 922704 (2014) https://doi.org/10.1117/12.2059221

KEYWORDS: Lawrencium, Reconstruction algorithms, Image quality, Image processing, Cameras, Algorithm development, Image restoration, Staring arrays, Image resolution, Image sensors

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Proceedings Article | 18 September 2014 Paper

Statistical bounds and maximum likelihood performance for shot noise limited knife-edge modeled stellar occultation

Patrick McNicholl, Peter Crabtree

Proceedings Volume 9227, 922707 (2014) https://doi.org/10.1117/12.2059317

KEYWORDS: Sensors, Diffraction, Spectral resolution, Neodymium, Stars, Performance modeling, Statistical modeling, Asteroids, Satellite imaging, Satellites

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Proceedings Article | 29 July 2014 Paper

Cramer-Rao lower bound and object reconstruction performance evaluation for intensity interferometry

Jean Dolne, David Gerwe, Peter Crabtree

Proceedings Volume 9146, 914636 (2014) https://doi.org/10.1117/12.2063418

KEYWORDS: Interferometry, Signal to noise ratio, Spatial frequencies, Reconstruction algorithms, Error analysis, Fourier transforms, Image analysis, Image restoration, Image resolution, Visibility

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Proceedings Article | 17 September 2013 Paper

Comparison of forward models and phase retrieval for image formation from intensity interferometer data

David Gerwe, Peter Crabtree, Richard Holmes, Jean Dolne

Proceedings Volume 8877, 88770F (2013) https://doi.org/10.1117/12.2026974

KEYWORDS: Signal to noise ratio, Phase retrieval, Data modeling, Image restoration, Reconstruction algorithms, Evolutionary algorithms, Interferometers, Interferometry, Artificial intelligence, Algorithm development

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Proceedings Article | 17 September 2013 Paper

Cramér-Rao bounds for variance of Fourier magnitude measurements

Richard Holmes, Brandoch Calef, David Gerwe, Jean Dolne, Peter Crabtree

Proceedings Volume 8877, 88770H (2013) https://doi.org/10.1117/12.2026971

KEYWORDS: Signal to noise ratio, Interferometry, Image acquisition, Solids, Error analysis, Spatial frequencies, Fourier transforms, Speckle imaging, Transform theory, Analytical research

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Proceedings Article | 8 June 2012 Paper

Polarimetric wavelet fractal remote sensing principles for space materials

George Giakos, Richard Picard, Phan Dao, Peter Crabtree, Patrick McNicholl, Jeff Petermann, Suman Shrestha, Chaya Narayan, Stefanie Marotta

Proceedings Volume 8364, 836405 (2012) https://doi.org/10.1117/12.920487

KEYWORDS: Fractal analysis, Amorphous silicon, Polarimetry, Wavelets, Polarization, Solar cells, Remote sensing, Scattering, LIDAR, Analytical research

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Proceedings Article | 10 May 2012 Paper

Effects of aberrations on image reconstruction of data from hybrid intensity interferometers

Jeremy Murray-Krezan, Peter Crabtree

Proceedings Volume 8407, 840703 (2012) https://doi.org/10.1117/12.919189

KEYWORDS: Phase retrieval, Image restoration, Lawrencium, Image retrieval, Signal to noise ratio, Reconstruction algorithms, Image processing, Image quality, Imaging systems, Spatial frequencies

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Proceedings Article | 14 September 2011 Paper

Geometric super-resolution via log-polar FFT image registration and variable pixel linear reconstruction

Peter Crabtree, Jeremy Murray-Krezan

Proceedings Volume 8165, 81650O (2011) https://doi.org/10.1117/12.894123

KEYWORDS: Image registration, Calibration, Super resolution, Lawrencium, Optical flow, Cameras, Spatial frequencies, Actuators, Modulation transfer functions, Image resolution

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Proceedings Article | 14 September 2011 Paper

A study of image reconstruction algorithms for hybrid intensity interferometers

Peter Crabtree, Jeremy Murray-Krezan, Richard Picard

Proceedings Volume 8165, 81650S (2011) https://doi.org/10.1117/12.894069

KEYWORDS: Signal to noise ratio, Reconstruction algorithms, Lawrencium, Image restoration, Phase retrieval, Image quality, Fourier transforms, Spatial frequencies, Image processing, Imaging systems

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Proceedings Article | 23 May 2011 Paper

A study of image quality for imagery generated by standard and hybrid intensity interferometers

Jeremy Murray-Krezan, Peter Crabtree, Richard Picard

Proceedings Volume 8044, 80440Q (2011) https://doi.org/10.1117/12.883458

KEYWORDS: Lawrencium, Signal to noise ratio, Phase retrieval, Image quality, Reconstruction algorithms, Image retrieval, Image quality standards, Fourier transforms, Imaging systems, Image restoration

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Proceedings Article | 1 October 2009 Paper

Object detection and characterization by monostatic ladar Bidirectional Reflectance Distribution Function (BRDF) using polarimetric discriminants

George Giakos, Richard Picard, Phan Dao, Peter Crabtree

Proceedings Volume 7482, 748208 (2009) https://doi.org/10.1117/12.830693

KEYWORDS: Bidirectional reflectance transmission function, Polarimetry, LIDAR, Aluminum, Polarization, Remote sensing, Wave plates, Specular reflections, Scattering, Reflectivity

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Proceedings Article | 4 May 2007 Paper

Binary wavefront control in the focal plane for improved fiber coupling in air-to-air laser communication

Peter Crabtree, Charles Woods, Jed Khoury, Matthew Goda, Michael Temple, Ed Watson

Proceedings Volume 6551, 65510M (2007) https://doi.org/10.1117/12.720077

KEYWORDS: Adaptive optics, Wavefronts, Binary data, Turbulence, Spatial light modulators, Wave propagation, Phase modulation, Wavefront sensors, Signal detection, Sensors

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Proceedings Article | 27 August 2005 Paper

Alternate tracking schemes for reducing fade probability

Peter Crabtree, Matthew Goda

Proceedings Volume 5894, 589402 (2005) https://doi.org/10.1117/12.615228

KEYWORDS: Turbulence, Atmospheric modeling, Adaptive optics, Cameras, Data modeling, Atmospheric propagation, Performance modeling, Receivers, Laser applications, Defense technologies

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Proceedings Article | 13 July 2000 Paper

Vision-based super resolution for recognizing small targets

Steven Gustafson, Peter Crabtree, Ryan Thomas

Proceedings Volume 4048, (2000) https://doi.org/10.1117/12.392020

KEYWORDS: Target recognition, Super resolution, Visualization, Integration, Signal processing, Data processing, Eye, Condition numbers, 3D acquisition, Organisms

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Showing 5 of 18 publications

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