Dr. Wellesley Pereira Profile

Dr. Wellesley Pereira

Principal Scientist

SPIE Involvement:

Editorial Board Member: Journal of Applied Remote Sensing | Author

Area of Expertise:

EO-IR sensors , Space Systems , Optics , Astrophysics , Infrared Physics

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 | 1 September 2015 Paper

Remote optical detection of ground vibrations

Robert Shroll, Benjamin St. Peter, Steven Richtsmeier, Bridget Tannian, Elijah Jensen, John Kielkopf, Wellesley Pereira

Proceedings Volume 9608, 96080K (2015) https://doi.org/10.1117/12.2190988

KEYWORDS: Cameras, Fourier transforms, Signal detection, Image filtering, Video, Sensors, Remote sensing, Signal to noise ratio, Modulation, Principal component analysis

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SPIE Journal Paper | 21 May 2015

Analysis of Air Force Weather Agency cloud data for assessing single and multiple scattering through clouds at optical wavelengths

John Roadcap, Jeannette van den Bosch, Wellesley Pereira

JARS, Vol. 9, Issue 01, 096049, (May 2015) https://doi.org/10.1117/12.10.1117/1.JRS.9.096049

KEYWORDS: Clouds, Scattering, Optical spheres, Particles, Water, Multiple scattering, Ocean optics, Liquids, Refractive index, Radiative transfer

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Proceedings Article | 12 September 2014 Paper

Feasibility considerations for a long-range passive vibrometer

Alan Marchant, Chad Fish, Jie Yao, Phillip Cunio, Wellesley Pereira

Proceedings Volume 9219, 92190F (2014) https://doi.org/10.1117/12.2064419

KEYWORDS: Sensors, Bidirectional reflectance transmission function, Signal to noise ratio, Staring arrays, Modulation, Spatial resolution, Scattering, Data processing, Scintillation, Telescopes

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Proceedings Article | 12 September 2014 Paper

A passive optical technique to remotely measure physical properties of a vibrating surface

Frank Clark, Ryan Penney, Wellesley Pereira, John Kielkopf, Jason Cline

Proceedings Volume 9219, 92190G (2014) https://doi.org/10.1117/12.2064366

KEYWORDS: Modulation, Light scattering, Bidirectional reflectance transmission function, Scattering, Sensors, Solids, Signal detection, Light, Reflectivity, Cameras

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Proceedings Article | 12 September 2014 Paper

Detecting small surface vibrations by passive electro-optical illumination

Matthew Buoni, Wellesley Pereira, Reed Weber, Carlos Garcia-Cervera

Proceedings Volume 9219, 92190E (2014) https://doi.org/10.1117/12.2060212

KEYWORDS: Buildings, Sensors, Light scattering, Reflection, Sun, Reflectivity, Bidirectional reflectance transmission function, MATLAB, Electro optical modeling, Polarization

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Proceedings Article | 23 May 2013 Paper

Background agnostic CPHD tracking of dim targets in heavy clutter

Adel El-Fallah, Aleksandar Zatezalo, Ronald P. Mahler, Raman Mehra, Wellesley Pereira

Proceedings Volume 8745, 87450C (2013) https://doi.org/10.1117/12.2017994

KEYWORDS: Target detection, Digital filtering, Sensors, Error analysis, Filtering (signal processing), Data analysis, Nonlinear filtering, Optical filters, 3D acquisition, Detection and tracking algorithms

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Proceedings Article | 14 April 2008 Paper

A simulation for hyperspectral thermal IR imaging sensors

Yit-Tsi Kwan, Steven Sawtelle, Uri Bernstein, Wellesley Pereira, Dave Less

Proceedings Volume 6966, 69661N (2008) https://doi.org/10.1117/12.777845

KEYWORDS: Sensors, Atmospheric modeling, Electro optical modeling, Hyperspectral simulation, Hyperspectral imaging, Infrared imaging, Thermal modeling, Thermography, Infrared sensors, 3D modeling

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Proceedings Article | 11 April 2008 Paper

Hyperspectral extensions in the MuSES signature code

Wellesley Pereira, David Less, Leonard Rodriguez, Allen Curran, Uri Bernstein, Yit-Tsi Kwan

Proceedings Volume 6965, 69650B (2008) https://doi.org/10.1117/12.783933

KEYWORDS: Sensors, Infrared signatures, Hyperspectral imaging, Bidirectional reflectance transmission function, Thermography, Thermal modeling, Image sensors, Infrared imaging, Hyperspectral simulation, Infrared sensors

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Showing 5 of 9 publications

Conference Committee Involvement (1)

Infrared Remote Sensing and Instrumentation XXIII

10 August 2015 | San Diego, California, United States

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