@unpublished{ZollmannBimber2007,
  author    = {Zollmann, Stefanie and Bimber, Oliver},
  title     = {Imperceptible Calibration for Radiometric Compensation},
  doi       = {10.25643/bauhaus-universitaet.809},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8094},
  year      = {2007},
  abstract  = {We present a novel multi-step technique for imperceptible geometry and radiometry calibration of projector-camera systems. Our approach can be used to display geometry and color corrected images on non-optimized surfaces at interactive rates while simultaneously performing a series of invisible structured light projections during runtime. It supports disjoint projector-camera configurations, fast and progressive improvements, as well as real-time correction rates of arbitrary graphical content. The calibration is automatically triggered when mis-registrations between camera, projector and surface are detected.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@unpublished{WetzsteinBimber2006,
  author    = {Wetzstein, Gordon and Bimber, Oliver},
  title     = {A Generalized Approach to Radiometric},
  doi       = {10.25643/bauhaus-universitaet.762},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-7625},
  year      = {2006},
  abstract  = {We propose a novel method that applies the light transport matrix for performing an image-based radiometric compensation which accounts for all possible types of light modulation. For practical application the matrix is decomposed into clusters of mutually influencing projector and camera pixels. The compensation is modeled as a linear system that can be solved with respect to the projector patterns. Precomputing the inverse light transport in combination with an efficient implementation on the GPU makes interactive compensation rates possible. Our generalized method unifies existing approaches that address individual problems. Based on examples, we show that it is possible to project corrected images onto complex surfaces such as an inter-reflecting statuette, glossy wallpaper, or through highly-refractive glass. Furthermore, we illustrate that a side-effect of our approach is an increase in the overall sharpness of defocused projections.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@techreport{WetzsteinBimber2007,
  author    = {Wetzstein, Gordon and Bimber, Oliver},
  title     = {Radiometric Compensation through Inverse Light Transport},
  doi       = {10.25643/bauhaus-universitaet.812},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8126},
  year      = {2007},
  abstract  = {Radiometric compensation techniques allow seamless projections onto complex everyday surfaces. Implemented with projector-camera systems they support the presentation of visual content in situations where projection-optimized screens are not available or not desired - as in museums, historic sites, air-plane cabins, or stage performances. We propose a novel approach that employs the full light transport between a projector and a camera to account for many illumination aspects, such as interreflections, refractions and defocus. Precomputing the inverse light transport in combination with an efficient implementation on the GPU makes the real-time compensation of captured local and global light modulations possible.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@misc{Wetzstein2006,
  type      = {Master Thesis},
  author    = {Wetzstein, Gordon},
  title     = {Radiometric Compensation of Global Illumination Effects with Projector-Camera Systems},
  doi       = {10.25643/bauhaus-universitaet.810},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8106},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2006},
  abstract  = {Projector-based displays have been evolving tremendously in the last decade. Reduced costs and increasing capabilities have let to a widespread use for home entertainment and scientific visualization. The rapid development is continuing - techniques that allow seamless projection onto complex everyday environments such as textured walls, window curtains or bookshelfs have recently been proposed. Although cameras enable a completely automatic calibration of the systems, all previously described techniques rely on a precise mapping between projector and camera pixels. Global illumination effects such as reflections, refractions, scattering, dispersion etc. are completely ignored since only direct illumination is taken into account. We propose a novel method that applies the light transport matrix for performing an image-based radiometric compensation which accounts for all possible lighting effects. For practical application the matrix is decomposed into clusters of mutually influencing projector and camera pixels. The compensation is modeled as a linear equation system that can be solved separately for each cluster. For interactive compensation rates this model is adapted to enable an efficient implementation on programmable graphics hardware. Applying the light transport matrix's pseudo-inverse allows to separate the compensation into a computational expensive preprocessing step (computing the pseudo-inverse) and an on-line matrix-vector multiplication. The generalized mathematical foundation for radiometric compensation with projector-camera systems is validated with several experiments. We show that it is possible to project corrected imagery onto complex surfaces such as an inter-reflecting statuette and glass. The overall sharpness of defocused projections is increased as well. Using the proposed optimization for GPUs, real-time framerates are achieved.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@techreport{KurzHaentschGrosseetal.2007,
  author    = {Kurz, Daniel and H{\"a}ntsch, Ferry and Grosse, Max and Schiewe, Alexander and Bimber, Oliver},
  title     = {Laser Pointer Tracking in Projector-Augmented Architectural Environments},
  doi       = {10.25643/bauhaus-universitaet.818},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8183},
  year      = {2007},
  abstract  = {We present a system that applies a custom-built pan-tilt-zoom camera for laser-pointer tracking in arbitrary real environments. Once placed in a building environment, it carries out a fully automatic self-registration, registrations of projectors, and sampling of surface parameters, such as geometry and reflectivity. After these steps, it can be used for tracking a laser spot on the surface as well as an LED marker in 3D space, using inter-playing fisheye context and controllable detail cameras. The captured surface information can be used for masking out areas that are critical to laser-pointer tracking, and for guiding geometric and radiometric image correction techniques that enable a projector-based augmentation on arbitrary surfaces. We describe a distributed software framework that couples laser-pointer tracking for interaction, projector-based AR as well as video see-through AR for visualizations with the domain specific functionality of existing desktop tools for architectural planning, simulation and building surveying.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@article{GrundhoeferSeegerHaentschetal.2007,
  author    = {Grundh{\"o}fer, Anselm and Seeger, Manja and H{\"a}ntsch, Ferry and Bimber, Oliver},
  title     = {Coded Projection and Illumination for Television Studios},
  organization    = {Bimber, Fak. M, BUW},
  doi       = {10.25643/bauhaus-universitaet.800},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8005},
  year      = {2007},
  abstract  = {We propose the application of temporally and spatially coded projection and illumination in modern television studios. In our vision, this supports ad-hoc re-illumination, automatic keying, unconstrained presentation of moderation information, camera-tracking, and scene acquisition. In this paper we show how a new adaptive imperceptible pattern projection that considers parameters of human visual perception, linked with real-time difference keying enables an in-shot optical tracking using a novel dynamic multi-resolution marker technique},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@techreport{GrundhoeferSeegerHaentschetal.2007,
  author    = {Grundh{\"o}fer, Anselm and Seeger, Manja and H{\"a}ntsch, Ferry and Bimber, Oliver},
  title     = {Dynamic Adaptation of Projected Imperceptible Codes},
  doi       = {10.25643/bauhaus-universitaet.816},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8168},
  year      = {2007},
  abstract  = {In this paper we present a novel adaptive imperceptible pattern projection technique that considers parameters of human visual perception. A coded image that is invisible for human observers is temporally integrated into the projected image, but can be reconstructed by a synchronized camera. The embedded code is dynamically adjusted on the fly to guarantee its non-perceivability and to adapt it to the current camera pose. Linked with real-time flash keying, for instance, this enables in-shot optical tracking using a dynamic multi-resolution marker technique. A sample prototype is realized that demonstrates the application of our method in the context of augmentations in television studios.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@techreport{GrundhoeferBimber2008,
  author    = {Grundh{\"o}fer, Anselm and Bimber, Oliver},
  title     = {Dynamic Bluescreens},
  doi       = {10.25643/bauhaus-universitaet.1233},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20080226-13016},
  year      = {2008},
  abstract  = {Blue screens and chroma keying technology are essential for digital video composition. Professional studios apply tracking technology to record the camera path for perspective augmentations of the original video footage. Although this technology is well established, it does not offer a great deal of flexibility. For shootings at non-studio sets, physical blue screens might have to be installed, or parts have to be recorded in a studio separately. We present a simple and flexible way of projecting corrected keying colors onto arbitrary diffuse surfaces using synchronized projectors and radiometric compensation. Thereby, the reflectance of the underlying real surface is neutralized. A temporal multiplexing between projection and flash illumination allows capturing the fully lit scene, while still being able to key the foreground objects. In addition, we embed spatial codes into the projected key image to enable the tracking of the camera. Furthermore, the reconstruction of the scene geometry is implicitly supported.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}
@unpublished{GrundhoeferBimber2006,
  author    = {Grundh{\"o}fer, Anselm and Bimber, Oliver},
  title     = {Real-Time Adaptive Radiometric Compensation},
  doi       = {10.25643/bauhaus-universitaet.784},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-7848},
  year      = {2006},
  abstract  = {Recent radiometric compensation techniques make it possible to project images onto colored and textured surfaces. This is realized with projector-camera systems by scanning the projection surface on a per-pixel basis. With the captured information, a compensation image is calculated that neutralizes geometric distortions and color blending caused by the underlying surface. As a result, the brightness and the contrast of the input image is reduced compared to a conventional projection onto a white canvas. If the input image is not manipulated in its intensities, the compensation image can contain values that are outside the dynamic range of the projector. They will lead to clipping errors and to visible artifacts on the surface. In this article, we present a novel algorithm that dynamically adjusts the content of the input images before radiometric compensation is carried out. This reduces the perceived visual artifacts while simultaneously preserving a maximum of luminance and contrast. The algorithm is implemented entirely on the GPU and is the first of its kind to run in real-time.},
  subject      = {Maschinelles Sehen},
  language  = {en}
}
@techreport{GrosseBimber2008,
  author    = {Grosse, Max and Bimber, Oliver},
  title     = {Coded Aperture Projection},
  doi       = {10.25643/bauhaus-universitaet.1234},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20080227-13020},
  year      = {2008},
  abstract  = {In computer vision, optical defocus is often described as convolution with a filter kernel that corresponds to an image of the aperture being used by the imaging device. The degree of defocus correlates to the scale of the kernel. Convolving an image with the inverse aperture kernel will digitally sharpen the image and consequently compensate optical defocus. This is referred to as deconvolution or inverse filtering. In frequency domain, the reciprocal of the filter kernel is its inverse, and deconvolution reduces to a division. Low magnitudes in the Fourier transform of the aperture image, however, lead to intensity values in spatial domain that exceed the displayable range. Therefore, the corresponding frequencies are not considered, which then results in visible ringing artifacts in the final projection. This is the main limitation of previous approaches, since in frequency domain the Gaussian PSF of spherical apertures does contain a large fraction of low Fourier magnitudes. Applying only small kernel scales will reduce the number of low Fourier magnitudes (and consequently the ringing artifacts) -- but will also lead only to minor focus improvements. To overcome this problem, we apply a coded aperture whose Fourier transform has less low magnitudes initially. Consequently, more frequencies are retained and more image details are reconstructed.},
  subject      = {Association for Computing Machinery / Special Interest Group on Graphics},
  language  = {en}
}