6,458 research outputs found
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
Earthquake Machine Lite: Activity 1 of 2
This activity is the first in a two part sequence designed to increase students' understandings about earthquakes. It will address the following questions: What is an earthquake?; What is the role of a model in science?; and How are scientific ideas constantly changing? The activity involves the construction of a model ('The Earthquake Machine') that allows students to explore stick-slip behavior of some faults. Teacher background material, references, standards alignments, and a zipped file containing a slide demonstration of the Earthquake Machine and supporting animations are provided. Educational levels: Middle school, High school
Fundamental solutions for water wave animation
This paper investigates the use of fundamental solutions for animating detailed linear water surface waves. We first propose an analytical solution for efficiently animating circular ripples in closed form. We then show how to adapt the method of fundamental solutions (MFS) to create ambient waves interacting with complex obstacles. Subsequently, we present a novel wavelet-based discretization which outperforms the state of the art MFS approach for simulating time-varying water surface waves with moving obstacles. Our results feature high-resolution spatial details, interactions with complex boundaries, and large open ocean domains. Our method compares favorably with previous work as well as known analytical solutions. We also present comparisons between our method and real world examples
Water wave animation via wavefront parameter interpolation
We present an efficient wavefront tracking algorithm for animating bodies of water that interact with their environment. Our contributions include: a novel wavefront tracking technique that enables dispersion, refraction, reflection, and diffraction in the same simulation; a unique multivalued function interpolation method that enables our simulations to elegantly sidestep the Nyquist limit; a dispersion approximation for efficiently amplifying the number of simulated waves by several orders of magnitude; and additional extensions that allow for time-dependent effects and interactive artistic editing of the resulting animation. Our contributions combine to give us multitudes more wave details than similar algorithms, while maintaining high frame rates and allowing close camera zooms
Water wave packets
This paper presents a method for simulating water surface waves as a displacement field on a 2D domain. Our method relies on Lagrangian particles that carry packets of water wave energy; each packet carries information about an entire group of wave trains, as opposed to only a single wave crest. Our approach is unconditionally stable and can simulate high resolution geometric details. This approach also presents a straightforward interface for artistic control, because it is essentially a particle system with intuitive parameters like wavelength and amplitude. Our implementation parallelizes well and runs in real time for moderately challenging scenarios
The 2009 Samoa and 2010 Chile Tsunamis as Observed in the Ionosphere using GPS Total Electron Content
Groundâbased Global Positioning System (GPS) measurements of ionospheric total electron content (TEC) show variations consistent with atmospheric internal gravity waves caused by ocean tsunamis following two recent seismic events: the Samoa earthquake of 29 September 2009 and the Chile earthquake of 27 February 2010. Both earthquakes produced ocean tsunamis that were destructive to coastal communities near the epicenters, and both were observed in tidal gauge and buoy measurements throughout the Pacific Ocean. We observe fluctuations in TEC correlated in time, space, and wave properties with these tsunamis using the Jet Propulsion Laboratoryâs Global Ionospheric Mapping software. These TEC measurements were bandâpass filtered to remove ionospheric TEC variations with wavelengths and periods outside the typical range for tsunamis. Observable variations in TEC appear correlated with the tsunamis in some locations (Hawaii and Japan), but not in others (Southern California or near the epicenters). Where variations are observed, the typical amplitude tends to be âŒ0.1â0.2 TEC units for these events, on the order of âŒ1% of the background TEC value. These observations are compared to estimates of expected tsunamiâdriven TEC variations produced by Embry Riddle Aeronautical Universityâs Spectral Full Wave Model, an atmosphereâionosphere coupled model, and are found to be in good agreement. Significant TEC variations are not always seen when a tsunami is present, but in these two events the regions where a strong ocean tsunami was observed coincided with clear TEC observations, while a lack of clear TEC observations coincided with smaller sea surface height amplitudes. There exists the potential to apply these detection techniques to realâtime GPS TEC data, providing estimates of tsunami speed and amplitude that may be useful for early warning systems
Ocean Wave Rendering with Whitecap in the Visual System of a Maritime Simulator
The whitecap is an important oceanographic phenomenon. However, existing whitecap rendering methods do not successfully generate realistic whitecaps. To solve this problem, this paper presents a real-time whitecap rendering method applied to the visual system of a maritime simulator. The method takes the vertical acceleration on the wave crest as the criterion of whitecap generation. The Fourier coefficient of the vertical acceleration is provided, and a continuous mathematical model computing the whitecap coverage is built. The vertical acceleration is the variable of the model. The life time of the whitecapâs existence can be controlled by the parameter of the model, and the parameter is computed with the genetic algorithm. The average of the computed whitecap coverage is equal to the whitecap coverage computed by the stochastic method and is close to the whitecap coverage computed by the empirical formula. The whitecap coverage is used as the blending factor to blend the pixel color of the whitecap texture and that of the sea surface. The presented method has sound theoretical support, with small computational complexity. The rendered whitecap is closer to the description of the Beaufort wind force scale than before
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