TY - INPR A1 - Grundhöfer, Anselm A1 - Bimber, Oliver T1 - Real-Time Adaptive Radiometric Compensation N2 - 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. KW - Maschinelles Sehen KW - CGI KW - Bildbasiertes Rendering KW - Display KW - Projektionsverfahren KW - Radiometrische Kompensation KW - Projektion KW - Projekor-Kamera System KW - Bildkorrektur KW - Visuelle Wahrnehmung KW - radiometric compensation KW - projection KW - projector-camera systems KW - image correction KW - visual perception Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-7848 ER - TY - JOUR A1 - Grundhöfer, Anselm A1 - Seeger, Manja A1 - Häntsch, Ferry A1 - Bimber, Oliver T1 - Coded Projection and Illumination for Television Studios N2 - 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 KW - Association for Computing Machinery / Special Interest Group on Graphics KW - CGI KW - Maschinelles Sehen KW - Virtuelle Studios KW - Erweiterte Realität KW - Kamera Tracking KW - Projektion KW - Virtual Studios KW - Augmented Reality KW - Camera Tracking KW - Projection Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-8005 ER - TY - RPRT A1 - Kurz, Daniel A1 - Häntsch, Ferry A1 - Grosse, Max A1 - Schiewe, Alexander A1 - Bimber, Oliver T1 - Laser Pointer Tracking in Projector-Augmented Architectural Environments N2 - 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. KW - Association for Computing Machinery / Special Interest Group on Graphics KW - CGI KW - Architektur KW - Maschinelles Sehen KW - Laserpointer Tracking KW - Erweiterte Realität KW - Interaktion KW - Projektion KW - Verteilte Systeme KW - Laser Pointer Tracking KW - Augmented Reality KW - Interaction KW - Projection KW - Distributed Systems Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-8183 ER - TY - RPRT A1 - Grundhöfer, Anselm A1 - Seeger, Manja A1 - Häntsch, Ferry A1 - Bimber, Oliver T1 - Dynamic Adaptation of Projected Imperceptible Codes N2 - 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. KW - Association for Computing Machinery / Special Interest Group on Graphics KW - CGI KW - Maschinelles Sehen KW - Erweiterte Realität KW - Kamera Tracking KW - Projektion KW - Augmented Reality KW - Camera Tracking KW - Projection Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-8168 ER - TY - RPRT A1 - Grundhöfer, Anselm A1 - Bimber, Oliver T1 - Dynamic Bluescreens N2 - 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. KW - Association for Computing Machinery / Special Interest Group on Graphics KW - CGI KW - Maschinelles Sehen KW - Farbstanzen KW - Erweiterte Realität KW - Projektion KW - Chroma Keying KW - Bildmischung KW - Augmented Reality KW - Projection KW - Chromakeying KW - Compositing Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20080226-13016 ER - TY - RPRT A1 - Grosse, Max A1 - Bimber, Oliver T1 - Coded Aperture Projection N2 - 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. KW - Association for Computing Machinery / Special Interest Group on Graphics KW - CGI KW - Projektion KW - Blende Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20080227-13020 ER -