Bryner D.,Naval Surface Warfare Center Panama City Division |
Bryner D.,Florida State University |
Srivastava A.,Florida State University |
Huynh Q.,Naval Surface Warfare Center Panama City Division
Computer Vision and Image Understanding | Year: 2013
We present a variational framework for naturally incorporating prior shape knowledge in guidance of active contours for boundary extraction in images. This framework is especially suitable for images collected outside the visible spectrum, where boundary estimation is difficult due to low contrast, low resolution, and presence of noise and clutter. Accordingly, we illustrate this approach using the segmentation of various objects in synthetic aperture sonar (SAS) images of underwater terrains. We use elastic shape analysis of planar curves in which the shapes are considered as elements of a quotient space of an infinite dimensional, non-linear Riemannian manifold. Using geodesic paths under the elastic Riemannian metric, one computes sample mean and covariances of training shapes in each classes and derives statistical models for capturing class-specific shape variability. These models are then used as shape priors in a variational setting to solve for Bayesian estimation of desired contours as follows. In traditional active contour models curves are driven towards minimum of an energy composed of image and smoothing terms. We introduce an additional shape term based on shape models of relevant shape classes. The minimization of this total energy, using iterated gradient-based updates of curves, leads to an improved segmentation of object boundaries. This is demonstrated using a number of shape classes in two large SAS image datasets.
Johnson B.A.,Naval Surface Warfare Center Panama City Division |
Matthews C.,Naval Surface Warfare Center Panama City Division
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016
The Art Gallery Problem (AGP) is the name given to a constrained optimization problem meant to determine the maximum amount of sensor coverage while utilizing the minimum number of resources. The AGP is significant because a common issue among surveillance and interdiction systems is obtaining an understanding of the optimal position of sensors and weapons in advance of enemy combatant maneuvers. The implication that an optimal position for a sensor to observe an event or for a weapon to engage a target autonomously is usually very clear after the target has passed, but for autonomous systems the solution must at least be conjectured in advance for deployment purposes. This abstract applies the AGP as a means to solve where best to place underwater sensor nodes such that the amount of information acquired about a covered area is maximized while the number of resources used to gain that information is minimized. By phrasing the ISR/interdiction problem this way, the issue is addressed as an instance of the AGP. The AGP is a member of a set of computational problems designated as nondeterministic polynomial-time (NP)-hard. As a member of this set, the AGP shares its members' defining feature, namely that no one has proven that there exists a deterministic algorithm providing a computationally-tractable solution to the AGP within a finite amount of time. At best an algorithm meant to solve the AGP can asymptotically approach perfect coverage with minimal resource usage but providing perfect coverage would either break the minimal resource usage constraint or require an exponentially-growing amount of time. No perfectly-optimal solution yet exists to the AGP, however, approximately optimal solutions to the AGP can approach complete area or barrier coverage while simultaneously minimizing the number of sensors and weapons utilized. A minimal number of underwater sensor nodes deployed can greatly increase the Mean Time Between Operational Failure (MTBOF) and logistical footprint. The resulting coverage optimizes the likelihood of encounter given an arbitrary sensor profile and threat from a free field statistical model approach. The free field statistical model is particularly applicable to worst case scenario modeling in open ocean operational profiles where targets to do not follow a particular pattern in any of the modeled dimensions. We present an algorithmic testbed which shows how to achieve approximately optimal solutions to the AGP for a network of underwater sensor nodes with or without effector systems for engagement while operating under changing environmental circumstances. The means by which we accomplish this goal are three-fold: 1) Develop a 3D model for the sonar signal propagating through the underwater environment 2) Add rigorous physics-based modeling of environmental events which can affect sensor information acquisition 3) Provide innovative solutions to the AGP which account for the environmental circumstances affecting sensor performance. © 2016 SPIE.
Cobb J.T.,Naval Surface Warfare Center Panama City Division |
Zare A.,University of Missouri
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
In this paper we describe an unsupervised approach to seabed co-segmentation over the multiple sonar images collected in sonar surveys. We adapt a traditional single image segmentation texton-based approach to the sonar survey task by modifying the texture extraction filter bank to better model possible sonar image textures. Two different algorithms for building a universal texton library are presented that produce common pixel labels across multiple images. Following pixel labeling with the universal texton library, images are quantized into superpixels and co-segmented using a DP clustering algorithm. The segmentation results for both texton library selection criteria are contrasted and compared for a labeled set of SAS images with various discernable textures. © 2013 SPIE.
Suiter H.R.,Naval Surface Warfare Center Panama City Division
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012
When using flat windows between an air medium and one with higher index of refraction, the surface becomes optically active and a number of aberrations are induced. One affecting the optical control of a remotely-piloted underwater vehicle is the apparent pincushion distortion resulting from Snell's law at the interface. Small wide-angle lenses typically have the opposite problem, a barrel distortion caused by limitations in the number of lens surfaces and the constraints of cost. An experimental calibration is described in which the barrel distortion of the lens compensated for most of the inherent pincushion of the change in medium. ZEMAXTM models will be used to elucidate this phenomenon with a published lens design.* With careful selection of the lens and additional corrector, the resultant image can be made almost rectilinear, thus easing steering control and automatic target recognition. © 2012 SPIE.
Gallagher D.G.,Naval Surface Warfare Center Panama City Division
Underwater Intervention Conference 2011, UI 2011 | Year: 2011
Maritime-Port Security Dive Operations became a higher priority after the terrorist attacks of September 11, 2001. These dive operations cross many geographic boundaries and regional jurisdictions, and are conducted by US Navy Explosive Ordnance Disposal (EOD), United States Coast Guard (USCG), Federal Bureau of Investigation (FBI), and Public Safety Dive (PSD) Teams. They include underwater search of ship hulls, piers, pilings, docks, and bottom berthing areas for improvised explosive devices (IEDs), contraband, mines, and other threats - And routinely occur in dark or turbid water in near zero visibility conditions. Consequently, there is high interest in the development and fielding of technology and training that can decrease the time needed to search an underwater area, increase the probability that threats will be found, and decrease the inherent risk to divers. Technology and training that can be used by multiple agencies - military and civilian - is essential. In addition, the National Science and Technology Council?s Domestic IED Subcommittee has determined that effective Waterborne IED Detect and Defeat Systems are a National Critical Need. 1 The Combating Terrorism Technical Support Office (CTTSO) oversees interagency programs that develop advanced technologies and missionfocused solutions for joint service operators to address current and emerging maritime threats.11 Under the Maritime-Port Security Counterterrorism Initiative Program, the Naval Surface Warfare Center - Panama City division (NSWC PCD); in partnership with Florida State University-Panama City (FSU-PC) and Sound Metrics Corporation; has developed a Diver-based Rapid Response Capability for search, detection, location, and identification of waterborne threats. This capability is provided through a commercial acoustic-lens imaging sonar, an advanced military diver maskmounted display system, and a missionspecific portable training program that can be used by military and civilian agencies.
Lance R.M.,Naval Surface Warfare Center Panama City Division |
Lance R.M.,Duke University |
Bass C.R.,Duke University
Diving and Hyperbaric Medicine | Year: 2015
The first cases of underwater blast injury appeared in the scientific literature in 1917, and thousands of service members and civilians were injured or killed by underwater blast during WWII. The prevalence of underwater blast injuries and occupational blasting needs led to the development of many safety standards to prevent injury or death. Most of these standards were not supported by experimental data or testing. In this review, we describe existing standards, discuss their origins, and we comprehensively compare their prescriptions across standards. Surprisingly, we found that most safety standards had little or no scientific basis, and prescriptions across standards often varied by at least an order of magnitude. Many published standards traced back to a US Navy 500 psi guideline, which was intended to provide a peak pressure at which injuries were likely to occur. This standard itself seems to have been based upon a completely unfounded assertion that has propagated throughout the literature in subsequent years. Based on the limitations of the standards discussed, we outline future directions for underwater blast injury research, such as the compilation of epidemiological data to examine actual injury risk by human beings subjected to underwater blasts. © 2015, South Pacific Underwater Medicine Society. All right reserved.
Tafuni A.,New York University |
Sahin I.,New York University |
Hyman M.,Naval Surface Warfare Center Panama City Division
Applied Ocean Research | Year: 2016
A numerical investigation of the bottom pressure and wave elevation generated by a planing hull in finite-depth water is presented. While the existing literature addresses the free-surface deformation and pressure field at the seafloor independently, this work proposes a direct comparison between the two hydrodynamic quantities. The dependence of the pressure disturbances at the ocean floor from the waves generated at the free-surface by a planing hull is studied for several values of both the depth and hull Froude numbers. The methodology employed is Smoothed Particle Hydrodynamics (SPH), a numerical technique based on the discretization of the continuum fields of hydrodynamics through mesh-less particles. The SPH code herein chosen is initially validated against experimental data for transom-stern flow. Subsequently, numerical simulations are presented for a planing hull in high-speed regimes. The results show a direct correlation between surface wave dynamics and hydrodynamic pressure disturbances at the seafloor as the value of the Froude number is varied. This is assessed by studying the inverse dependence of the low-pressure wake angle with the Froude number and by comparison of SPH results with similar works in the cited literature. © 2016 Elsevier Ltd.
Gallagher D.,Naval Surface Warfare Center Panama City Division
Sea Technology | Year: 2012
Maritime security dive operations cross many geographic boundaries and regional jurisdictions. Performed routinely in dark or turbid water in near-zero visibility conditions, these operations include underwater searches of ship hulls, piers, docks and bottom berthing areas for contraband, mines and other threats. The US government's Combating Terrorism Technical Support Office oversees interagency programs that are developing technologies and solutions to address current and emerging maritime threats. Under its Maritime-Port Security. ROVs, AUVs and site-specific sensors are adding significant security response, monitoring and situational awareness for the maritime domain. However, divers remain an essential component to maritime domain security capability as they are a widely distributed, highly flexible, indigenous and rapidly deployable response asset. The Naval Surface Warfare Center Panama City Division has developed a number of diver mask-mounted display systems.
Bouchard A.,Naval Surface Warfare Center Panama City Division |
Tatum R.,Naval Surface Warfare Center Panama City Division
OCEANS 2015 - MTS/IEEE Washington | Year: 2015
The words failure and success are simple binary terms used to describe the outcomes of maritime autonomous behavior, yet how to draw the line separating the two stark realities demonstrates the subtle nature of this problem. If how to judge success or failure is improperly performed, users of systems that rely upon autonomous behavior may quickly find their initial trust misplaced and in some cases, the trust may never be recovered. A loss of trust or an unwillingness to trust newer technologies can greatly hinder the transition and use of such technologies. Acceptance of current and future maritime autonomy so that its use is more ubiquitous and commonplace requires the establishment of rigorous techniques for which clearly defined verification of autonomy can be performed. Therefore, it is critical that verification of maritime autonomous systems be tenably and consistently implemented. For our work, we identify some of the difficulties with verification efforts with respect to general autonomy and not only maritime autonomy. In an attempt to address the difficulties, we present the potential use of techniques found within other fields to assist with some of these difficulties. © 2015 MTS.
News Article | June 4, 2016
U.S. Navy researchers have developed a high-tech, in-helmet display that will assist underwater personnel by using augmented reality. The device not only shows design inspiration from the world of sci-fi but is said to increase the safety and efficiency of divers in the line of duty. Those who took diving as a hobby already know that the experience is fun, but it comes with a degree of clumsiness and isolation. Standard masks narrow down the field of view, while the neoprene gloves hinder precision. Professional divers could use any help they can get to make their work easier and more streamlined. The Navy acknowledges their need: it has built an underwater head-up display (HUD) prototype that allows divers to check their location and tap into sonar data by looking straight ahead, thus eliminating the need for a smartwatch display. The leader of the research team, Dennis Gallagher, says that "a capability similar to something from an Iron Man movie" is in store to those who will use the new helmet. To put it shortly, all the relevant information can be viewed "within the helmet." Surface sources, such as a ship, can send out information to the Divers Augmented Vision Display (DAVD). Future improvements to the device could bring sonar sensors mounted on the helmet, making it even easier to collect and display info. Underwater work usually involves low-light conditions or salty water; any additional tidbit of visual clue can assist the process. The DAVD displays the image in front of both eyes to provide visual depth, which is essential to creating accurate augmented reality. The Navy's device is not the only HUD in use by the military. The technology is also available to fighter jet pilots. However, the challenge to creating a wireless, submerged version is a daunting task for researchers. The team is building the prototype at the Naval Surface Warfare Center Panama City Division. Although still in its early stage, the product could grow to see widespread use both by rescue and military authorities and the consumer market. In-water simulation testing is set for October, the Navy says. Other defense organizations, such as DARPA, are working on their own HUD for ground forces, and you can read all about it in our coverage. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.