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The new illumination technique for tomography is still in the testing phase. In order to find out how different kinds of light work on CT images, photographer Volker Steger has recorded different lighting situations. Here is the CT image of a head in a forest near Vancouver. (Photo: Welwitschia Hospital, Walvis Bay, Namibia / Siemens Healthcare / V. Steger)

Das neue Beleuchtungsverfahren für Tomografien befindet sich noch in der Testphase. Um herauszufinden, wie verschiedene Lichtarten auf CT-Bilder wirken, hat Fotograf Volker Steger verschiedene Lichtsituationen aufgenommen. Hier ist das CT-Bild eines Kopfes in einem Wald bei Vancouver eingeblendet. (Foto: Welwitschia Hospital, Walvis Bay, Namibia/Siemens Healthcare/V. Steger)

The new illumination technique for tomography is still in the testing phase. In order to find out how different kinds of light work on CT images, photographer Volker Steger has recorded different lighting situations. Here is the CT image of a head in a forest near Vancouver. (Photo: Welwitschia Hospital, Walvis Bay, Namibia / Siemens Healthcare / V. Steger)

Computer and magnetic resonance imaging (CT and MRI) have long since become indispensable tools for physicians and doctors. However, the images do not optimally depict the human body. The reason: The CT images are not sufficiently well lit. Now researchers from Siemens have developed a software that visualizes image data photo-realistic and three-dimensional. The technology has been borrowed by IT professionals in the film industry.

It was the sunlight of Italy that made Goethe swarm. Above all, he was impressed by how the "tremendous light" worked on colors. When Goethe comes to Naples on his Italian journey in May 1787, he remembers the bright red carriages, the colorful clothing of the people, the multicolored ornamental flowers on hats, furniture and houses. In fact, the poet's intense play of colors becomes too colorful, but soft colors can not stand against the strong sunlight: "The most vivid color is muted by the tremendous light, and because all the colors, every green of the trees and plants, the yellow, brown, and red Soil in full force on the eye, so even the colored flowers and clothes enter into the general harmony. "

What once astonished Goethe, doctors now make use of when they examine CT scans. For put in the right light medical image data reveal information that can make diagnoses more sound. For this, however, a corresponding software is necessary. They were created by Siemens developers - and used it for the filmmakers in Hollywood. More specifically, companies like Pixar, which specialize in computer-generated animation. When creating films like "Monster Uni" or "Toy Story", light specialists play an important role. They ensure that the light falls as naturally as possible, is reflected or absorbed in the animated scenes. "Cinematic Rendering" is the name of the Hollywood Nerds.

The biggest challenge

But light is not the same light. The sun makes objects shine differently than a lamp and - as Goethe described it - light incidence and intensity differ depending on the geographic location. This also poses a particular difficulty for the creators of animated films, especially when they want to show animated characters and real actors together in one scene - for example in the "Lord of the Rings", when the hobbit Frodo and the computer-generated Gollum stand opposite each other.

"This is very challenging and one of the biggest challenges in our field, " says Mark Sawicki of the animation department of the New York Film Academy in Los Angeles. "That's because natural light and mathematically simulated light are by no means the same." That's why photographers try to capture the ambient light with a panoramic camera during filming. A photographer takes on the film backdrop from all imaginable angles and with different apertures and shutter speeds. Last but not least, a computer program processes the light data and transmits it to the animated characters. display

The light-joer

This software is also interesting for the IT specialists from Siemens. However, they did not want to imitate a particular light from a particular location, but collect as many lights from numerous locations as possible with the camera. Their goal: to gain more information from CT and MRI data. The way: Bones, tendons or muscles are illuminated with different types of light and from different angles of incidence and thus provide more details for a well-founded diagnosis.

In order to assemble different types of light, the computer researchers have hired the Mønchner photographer Volker Steger. In the name of medicine, he goes on a world-wide hunt for lights and introduces various natural and artificial light situations. His panoramic photos form the background on the computer, into which the tomographic images of a human are then embedded. "Lightmap", ie light card, christened the Siemens programmers the sceneries. Volker Steger photographed lakes, subway stations or photographed welding works in a tunnel.

As far as the type and number of possible scenes and locations are concerned, Volker Steger knows no bounds. But Goethe would probably recommend him to capture the "tremendous light" of Italy in any case.

The whole story about the "Juggers of Virtual Light" can be found in the July issue of bild der wissenschaft.

Science.de - Karin Schlott
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