989 research outputs found
Virtual Reality and Oceanography: Overview, Applications, and Perspective
With the ongoing, exponential increase in ocean data from autonomous platforms, satellites, models, and in particular, the growing field of quantitative imaging, there arises a need for scalable and cost-efficient visualization tools to interpret these large volumes of data. With the recent proliferation of consumer grade head-mounted displays, the emerging field of virtual reality (VR) has demonstrated its benefit in numerous disciplines, ranging from medicine to archeology. However, these benefits have not received as much attention in the ocean sciences. Here, we summarize some of the ways that virtual reality has been applied to this field. We highlight a few examples in which we (the authors) demonstrate the utility of VR as a tool for ocean scientists. For oceanic datasets that are well-suited for three-dimensional visualization, virtual reality has the potential to enhance the practice of ocean science
FEASIBILITY OF UNDERWATER LIDAR TECHNOLOGY FOR BOTTOM SENSING
Lasers have been used for several decades to perform multiple functions in areas such as communication, detection, and imaging. Only recently have lasers been used to operate in the navigational realm, particularly for land vehicles such as self-driving cars. This technology has not been used to a wide extent under the surface of the ocean, however, due to the high scattering and absorption properties of seawater. Very little research on laser propagation has been done in areas of the ocean such as below the euphotic zone where the absorption of light is minimized due to the lack of organic material. This paper assesses the feasibility of lasers to be used for underwater navigational purposes and act as an alternative to existing bathymetric sensing devices. This is done by creating a computer model based on the Beer-Lambert law and the general lidar equation. Additionally, the stealth capabilities of a laser bathymetric device is discussed.Approved for public release. Distribution is unlimited.Lieutenant, United States NavyNIW
Field deployable dynamic lighting system for turbid water imaging
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2011The ocean depths provide an ever changing and complex imaging environment.
As scientists and researches strive to document and study more remote and
optically challenging areas, specifically scatter-limited environments. There is a
requirement for new illumination systems that improve both image quality and
increase imaging distance.
One of the most constraining optical properties to underwater image quality are
scattering caused by ocean chemistry and entrained organic material. By
reducing the size of the scatter interaction volume, one can immediately improve
both the focus (forward scatter limited) and contrast (backscatter limited) of
underwater images. This thesis describes a relatively simple, cost-effective and
field-deployable low-power dynamic lighting system that minimizes the scatter
interaction volume with both subjective and quantifiable improvements in imaging
performance
Enhancing the detection and classification of coral reef and associated benthic habitats: A hyperspectral remote sensing approach
Coral reefs and associated benthic habitats are heterogeneous in nature. A remote sensor designed to discriminate these environments requires a high number of narrow, properly placed bands which are not currently available in existing satellite sensors. Optical hyperspectral sensors mounted on aerial platforms seem to be appropriate for overcoming the lack of both high spectral and spatial resolution of satellite sensors. This research presents results of an innovative coral reef application by such a sensor. Using hyperspectral Airborne Imaging Spectroradiometer for Applications (AISA) Eagle data, the approach presented solves the confounding influence of water column attenuation on substrate reflectance on a per-pixel basis. The hyperspectral imagery was used in band ratio algorithms to derive water depth and water column optical properties (e.g., absorption and backscattering coefficients). The water column correction technique produced a bottom albedo image which revealed that the dark regions comprised of sea grasses and benthic algae had albedo values ≈15%, whereas sand- and coral-dominated areas had albedos \u3e30% and ≈15–35%, respectively. The retrieved bottom albedo image was then used to classify the benthos, generating a detailed map of benthic habitats, followed by accuracy assessment
A Survey of Ocean Simulation and Rendering Techniques in Computer Graphics
This paper presents a survey of ocean simulation and rendering methods in
computer graphics. To model and animate the ocean's surface, these methods
mainly rely on two main approaches: on the one hand, those which approximate
ocean dynamics with parametric, spectral or hybrid models and use empirical
laws from oceanographic research. We will see that this type of methods
essentially allows the simulation of ocean scenes in the deep water domain,
without breaking waves. On the other hand, physically-based methods use
Navier-Stokes Equations (NSE) to represent breaking waves and more generally
ocean surface near the shore. We also describe ocean rendering methods in
computer graphics, with a special interest in the simulation of phenomena such
as foam and spray, and light's interaction with the ocean surface
Fluids real-time rendering
In this thesis the existing methods for realistic visualization of
uids
in real-time are reviewed. The correct handling of the interaction of light
with a
uid surface can highly increase the realism of the rendering, therefore
method for physically accurate rendering of re
ections and refractions will be
used. The light-
uid interaction does not stop at the surface, but continues
inside the
uid volume, causing caustics and beams of light. The simulation
of
uids require extremely time-consuming processes to achieve physical
accuracy and will not be explored, although the main concepts will be given.
Therefore, the main goals of this work are:
Study and review the existing methods for rendering
uids in realtime.
Find a simpli ed physical model of light interaction, because a complete
physically correct model would not achieve real-time.
Develop an application that uses the found methods and the light
interaction model
A Comprehensive Survey of Deep Learning in Remote Sensing: Theories, Tools and Challenges for the Community
In recent years, deep learning (DL), a re-branding of neural networks (NNs),
has risen to the top in numerous areas, namely computer vision (CV), speech
recognition, natural language processing, etc. Whereas remote sensing (RS)
possesses a number of unique challenges, primarily related to sensors and
applications, inevitably RS draws from many of the same theories as CV; e.g.,
statistics, fusion, and machine learning, to name a few. This means that the RS
community should be aware of, if not at the leading edge of, of advancements
like DL. Herein, we provide the most comprehensive survey of state-of-the-art
RS DL research. We also review recent new developments in the DL field that can
be used in DL for RS. Namely, we focus on theories, tools and challenges for
the RS community. Specifically, we focus on unsolved challenges and
opportunities as it relates to (i) inadequate data sets, (ii)
human-understandable solutions for modelling physical phenomena, (iii) Big
Data, (iv) non-traditional heterogeneous data sources, (v) DL architectures and
learning algorithms for spectral, spatial and temporal data, (vi) transfer
learning, (vii) an improved theoretical understanding of DL systems, (viii)
high barriers to entry, and (ix) training and optimizing the DL.Comment: 64 pages, 411 references. To appear in Journal of Applied Remote
Sensin
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