# Forum for Science, Industry and Business

Search our Site:

## Making Waves

29.06.2017

Computer scientists use wave packet theory to develop realistic, detailed water wave simulations in real time. Their results will be presented at this year’s SIGGRAPH conference.

Think about the last time you were at a lake, river, or the ocean. Remember the ripples of the water, the waves crashing against the rocks, the wake following a boat, the sun reflecting off the crests? Amazingly, the mathematical equations describing many of these phenomena have been known for over a hundred years.

Wave packet theory has inspired a new water wave simulation algorithm. The pictures are screenshots taken from the software developed by the team.

IST Austria

Wave packet theory has inspired a new water wave simulation algorithm. The pictures are screenshots taken from the software developed by the team.

IST Austria

The trouble is, actually solving them is extremely difficult and costly, making accurate, realistic simulations a significant problem for computer scientists, visual artists, and others. Now, computer scientists at the Institute of Science and Technology Austria (IST Austria) and Nvidia have introduced a novel representation of waves that improves computational efficiency by at least an order of magnitude. Based on principles of theoretical physics, their method allows for significantly more visual detail as well as a greater degree of user control.

As the equations modeling water surface waves are so difficult to solve in their original form, when studying these equations, researchers typically assume that the waves are not “too” big. This simplifies the problem enough for their work, but not enough to make it tractable for computer graphics.

In the past, this was addressed by making further simplifying assumptions and then using numerical methods to solve the equations. In this approach, the water waves are represented by a grid of points at different heights above the water surface, and motion is simulated by repeatedly updating the heights of the points based on the heights of their neighbors.

However, the visual quality of the simulation then depends on how fine the grid is, and it is moreover impossible to quickly produce an image of the waves in the far-off future, as these updates—or time-steps—must be computed one after another. An initial leap was made in 2007, when another team of researchers departed from the idea of a wave stored on a grid, and instead modeled the crest of each wave as a chain of points, and allowed those points to move along the surface as real waves would.

Now, IST Austria Professor Chris Wojtan and former IST Austria postdoc Stefan Jeschke have applied ideas from theoretical physics to develop a new type of representation of the waves as packets. Each wave packet contains a collection of similar wavelengths, and then larger wave formations are created by adding individual packets together.

Breaking up the waves in this way is not new to physics, but it is new to computer graphics, and in this way, the team has developed a simulation that more versatile and physically plausible than previous methods. Moreover, as their method is largely independent of time-steps and does not rely on a computational grid, the user can look very far into the future (or past) of the simulation, and examine the waves arbitrarily closely. Important effects, such as reflection, dispersion, refraction, diffraction, and dissipation, can be included with minimal extra work, further increasing the quality and believability of the simulation.

Besides believability, computing cost and efficiency are crucial considerations for any simulation—and the team’s method improves on previous methods in this area as well. “When we want to optimize a computer simulation, we have to think about what information we’re storing, how much of it we’re storing, and what it costs to update everything,” explains Chris Wojtan. “In this case, each wave packet is relatively cheap to store and update. Since each wave packet is computed in parallel, the number of packets is up to the user, and can be decided based on their needs and their system’s capabilities.”

“It’s popular with visual artists as well,” adds Stefan Jeschke. “If a movie director wants to make the waves around some monster bigger—even if physics doesn’t agree—it is easy to adjust the wave height in a particular area, simply by changing the wave packets in that region. When the visualization is based on small, sequential time-steps, effecting one tiny change could mean running another twenty-hour computation, with the possibility that the next version would also be rejected.”

In addition to implementing the idea of wave packets, Jeschke and Wojtan also developed a new theory for simulating wakes—the trail of water that follows an object moving on the water’s surface. Again, they appealed to theoretical physics to figure out which waves are visually dominant, allowing insignificant motion to be ignored and cutting down on computing costs. The team is currently working on the next iteration of their method, but the source code for their current simulation software can be downloaded via the link below. A video of the software in action is also available (see below).

Chris Wojtan obtained his doctorate in 2010 from the Georgia Institute of Technology. Immediately thereafter, he joined IST Austria as an Assistant Professor, where he leads the group in computer graphics and physics simulation. He became a full Professor in 2015. Stefan Jeschke received his PhD in 2005 from the University of Rostock. After postdoc positions in Vienna and Arizona, he conducted research at IST Austria in the Wojtan group from 2012-2016. He joined Nvidia as a researcher and developer in 2016.

### Weitere Informationen:

https://www.youtube.com/watch?v=A2auK5Sf4gY / Video: Water Wave packets

Dr. Elisabeth Guggenberger | idw - Informationsdienst Wissenschaft

### More articles from Information Technology:

Researchers illuminate the path to a new era of microelectronics
23.04.2018 | Boston University College of Engineering

Researchers achieve HD video streaming at 10,000 times lower power
20.04.2018 | University of Washington

### Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

### Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

### Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

### Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

### Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige