ShadowAReality - Photorealistic Rendering in AR (Augmented Reality)
Description
Nowadays, Computer Graphics has already become a science in itself. There are a lot of possibilities to render realistic images of virtual objects that don't even exist. However, in augmented- or mixed reality applications
the real scene is augmented by virtual objects, e. g. combining these two worlds. The problem with such
applications that give us the illusion of
another existing, but virtual, object is the lack of shadow casting
between these two worlds. Shadows are an important
aspect for perception of spatial relationships between
objects. Thus, they increase the visual realism of the scene.
Increasing visual realism is meant in terms of being able to visually track the virtual objects in the real environment. If you use an augmented- or mixed reality application and know where a virtual object is positioned, you can easily interact with it spatially. This is the most used interaction model between humans and virtual objects in augmented- and mixed reality
applications, due to its intuitive nature.
Imagine the real world, where everything is shadowed; real objects are lit because of a light source and cast shadows onto other real objects. In a similar way it is possible to render virtual shadowed objects in real-time. In augmented- and mixed reality applications the real and virtual objects are combined. Real Objects cast
shadows onto other real objects but lack
shadowcasting onto virtual ones and the other way round. This effect would complement the scene for better visual perception. Therefore the user would be enabled to measure the distances between real and virtual objects.
Augmenting an image of a real scene, which was captured by a camera, with virtual objects is complicated. On the one hand some parameters have to be configured very precisely to make the object and its shadow which is cast onto the real environment look as realistic as possible. On the other hand there is no need to waste implementation or render time with paramters
which our perception is not sensitive to. The goal of this thesis is to show the important aspects of adding the effect of shadow casting of objects in augmented- and mixed reality environments.
Publications
Photorealism or/and Non-Photorealism in Augmented Reality , Haller M., In ACM SIGGRAPH International Conference on Virtual Reality Continuum and its Applications in Industry, VRCAI 2004, pp. 189- 196, Singapore.
A real-time shadow approach for an Augmented Reality application using shadow volumes , Haller M., Drab S., Hartmann W., Zauner J., In VRST 2003, ACM Symposium on Virtual Reality Software and Technology, pp. 56-65, ACM Press, Osaka, October 2003.
Echtzeitrendering von Schattenwurf in Augmented Reality Anwendungen, Drab S., Master Thesis, Upper Austria University of Applied Sciences, Media Technology and Design, Hagenberg, 2003.
Additional Data
In ShadowAReality both real and virtual objects cast shadows onto real and virtual objects.
Some nice movies related to ShadowAReality.
We used shadow volumes for the real-time shadows. The figure in middle shows the stencil buffer.
Finally, we integrated some nice bump-mapping effects to achieve more realism.
