Realistic shadows for digital worlds: Computer scientist from Cluster of Excellence honored with European research award

In computer games like Tomb Raider a player has to explore caves and search temples for precious antiques. But the fun at the computer is gone if light and shadow are not realistic in such virtual rooms and if the graphical display is too slow. A Saarbrücken computer scientist has solved both problems with his methods — even though he is only 35. Tobias Ritschel was honored at the Eurographics conference in Strasbourg with the most important computer graphics award in Europe.

To make computer-generated images look real, the play of light and shadow must be shown in a realistic way. In virtual environments, like in computer games, this consumes a lot of computing power, because the players are moving around within them and exploring them from different perspectives.

The lighting conditions must be computed not just for one picture, but for many per second. Not only is computational cost a challenge, but also details like so-called concealed lighting, or the depiction of contact shadows. The first occurs if light is spatially reflected and therefore certain objects are illuminated. Contact shadows are the dark, narrow bands on material that form at the points where floor and wall meet or where objects are placed on the ground. “This, in particular, is important for human cognition”, explains Tobias Ritschel, since “the contact shadows are providing the spectator with the information that the object is not flying.”

The Ph.D. computer scientist is leader of the junior research group “Rendering and GPUs” at the Cluster of Excellence “Multimodal Computing and Interaction”. Ritschel found an efficient way to compute all the lighting conditions in scenes, for example in computer games, as well as on the surfaces of digital, three-dimensional objects. The young researcher will now continue to work on the automatization of the artistic working process. An additional step towards that goal could be his current project: Together with his group he developed a method that provides faster sorting of images. An algorithm arranges them in the right order with the aid of certain visual characteristics like size and brightness. It distributes the images consistently over the free space on the screen to create a harmonious overall picture. “What is special is that our program captures what the user wants”, explains Ritschel. “He only needs to drag three or more pictures to certain places; for example, he might drag two to the top left corner and one to the bottom right corner. The program computes the requested order and starts arranging the images in a corresponding way”. This software offers new possibilities not only for photo editors or photographers, but also for online stores and art museums.


The Eurographics Young Researcher Award

The members of the independent European Association for Computer Graphics (Eurographics) honored Ritschel with the Young Researcher Award because he made a crucial contribution to his subject, despite being just at the beginning of his career. They called his further ideas and his wide-ranging research “remarkable”, especially Ritschel’s research on cognition of computer-generated stereoscopic images — two-dimensional pictures that convey an impression of spatial depth. Their statement reads as follows: “His work has the distinction of technical excellence, an independent mind, creativity and relevant results. His productivity is remarkably outstanding, he publishes in the most renowned journals and at the most important conferences” Hans-Peter Seidel, Director at the Max Planck Institute for Informatics in Saarbrücken and speaker of the Cluster of Excellence, says: “This award is the highest honor in Europe for researchers in computer graphics at Ritschel’s age”, he says of the award. Two years ago, he himself was honored by Eurographics: With the so-called Eurographics Distinguished Career Award, the association honored not only Seidel’s pioneering scientific contributions, but also his efforts in teaching and graduating excellent university educators for Europe. Seidel is convinced that there is yet more to expect of Ritschel’s research work.


Background information about Tobias Ritschel

Ritschel received his computer science degree from the University Koblenz-Landau; in 2009 he defended his dissertation at Saarland University. He did his doctoral research under the supervision of Professor Hans-Peter Seidel. Two years later, he received the Eurographics Thesis Award. In 2010 he did research at the computer graphics group of Telekom ParisTech. Since June 2013, he is leader of the junior research group “Rendering and GPUs” at the Cluster of Excellence “Multimodal Computing and Interaction”. Ritschel puts emphasis on teaching as well as research. In his lectures on “Creative Computing” he combines computer science with art; at the association “MINT Campus Alte Schmelz” he teaches high school students how to generate three-dimensional graphics. “I have a great time doing that. It is fascinating to watch how the new generation of students uses the Internet to learn new skills”, says Ritschel.


Background of computer science in Saarbrücken at Saarland University:

The core of computer science in Saarbrücken is the faculty of computer science. Only a few meters away on campus are seven more internationally well-respected research institutes. Apart from the two Max Planck Institutes, for Informatics and Software Systems, these are the German Research Center for Artificial Intelligence (DFKI), the Center for Bioinformatics, the Center for IT-Security, Privacy and Accountability (CISPA) and the Cluster of Excellence “Multimodal Computing and Interaction”.


Press pictures are available at:


Further information:

Tobias Ritschel



Further questions can be addressed to:

Dr. Tobias Ritschel
Cluster of Excellence / Saarland University
E-Mail: ritschel(at)
Phone: +49 681 9325-4041



Gordon Bolduan
Science Communication
Competence Center Computer Science Saarland
Email: bolduan(at)
Tel: +49 681 302 70741



computer graphics award eurographics Young Reseracher Award 2014
Tobais Ritschel has won the Eurographics Young Researcher Award 2014.

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