We present a method that makes the use of photon tracing methods feasible for complex scenes when a totally accurate solution is not essential. This is accomplished by using orientation lightmaps, which average the il...
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We present a method that makes the use of photon tracing methods feasible for complex scenes when a totally accurate solution is not essential. This is accomplished by using orientation lightmaps, which average the illumination of complex objects depending on the surface normal. Through this averaging, they considerably reduce the variance of the stochastic solution. In order to use these specialised lightmaps, which consume comparatively small amounts of memory, no changes have to be made to the basic photon tracing algorithm. Also, they can be freely mixed with normal lightmaps. This gives the user good control over the amount of inaccuracy he introduces by their application. The area computations necessary for their insertion are performed using a stochastic sampling method that performs well for highly complex objects.
We present a method to measure reflectance and texture of surfaces in a one step process. For later use in digital image synthesis, it is mandatory to separate the gathered intensity values into these two parts to eli...
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We present a method to measure reflectance and texture of surfaces in a one step process. For later use in digital image synthesis, it is mandatory to separate the gathered intensity values into these two parts to eliminate highlighting artifacts from textures. Our image based measurement system delivers bidirectional reflectance distribution function (BRDF) values distributed over the surface of the material under investigation. After fitting a reflectance model to the gathered data, we estimate the modulation of the diffuse reflectance coefficient which represents the texture. The last step analyzes the texture to get a parameterized and compact description of the measured surface properties. These results allow us to apply the gathered surface properties to objects with arbitrary shape and size. To keep the measurement system simple, a standard CCD camera and light source are used.
In contrast to optical imagery, modern high resolution IFSAR sensors deliver intensity images and corresponding interferometric height and coherence data from a single flight path at pixel sizes of 30 cm to 10 cm. Due...
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ISBN:
(纸本)0769507506
In contrast to optical imagery, modern high resolution IFSAR sensors deliver intensity images and corresponding interferometric height and coherence data from a single flight path at pixel sizes of 30 cm to 10 cm. Due to the all-weather, day-night applicability of SAR sensors, multiple views over short time can be easily obtained. However, many image users find it difficult to "read" radar images. They differ from the natural human visual impression and the familiar analogy communicated by optical imagery. The goal of our work is to convert radar data into models of the terrain and render those models in analogy to the optical sensing approach that the human visual system represents. Therefore intelligent combinations of multiple views and measurements from all IFSAR data sources available are necessary to help to overcome problems inherent in the SAR data as e.g., blur, speckle, layover and shadow. Using basic image analysis methods we present in this paper our first fully automated approach to separate buildings from other objects in an IFSAR dataset. The building shapes are reconstructed using a simple building model and the results are compared to measurements made from optical imagery.
Geometric reconstruction of human scale features gets feasible from airborne single pass IFSAR sensors. IFSAR data is corrupted by blur, speckle noise, and other view dependent effects as e.g., layover and shadows. Es...
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Geometric reconstruction of human scale features gets feasible from airborne single pass IFSAR sensors. IFSAR data is corrupted by blur, speckle noise, and other view dependent effects as e.g., layover and shadows. Especially in case of buildings, those phenomenological features may also provide valuable information about the underlying structure. Combining multiple views and multiple data types of the same scene the exploitation of this information gets feasible. The authors use information from the interferometric height and coherence data to separate regions containing buildings from other objects in the scene. Shadow information from magnitude images is then used to delimit the exact boundaries of the buildings further. Rectangles are fit to the selected points and compared to ground truth measurements manually derived from optical images.
Models of the real world are at least 3-dimensional and require the technologies of image processing and computergraphics. We see the processing of images, be they of the real world or of models in a computer, as one...
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ISBN:
(纸本)9539676924
Models of the real world are at least 3-dimensional and require the technologies of image processing and computergraphics. We see the processing of images, be they of the real world or of models in a computer, as one and the same basic technology, namely "digital visual information processing". This paper seeks to illustrate and justify this point-of-view by means of examples taken mostly from the work at the author's institute.
In order to display huge scenes with virtual human inhabitants evolving inside a virtual city, we propose a methodology to create and manage different levels of detail for a well-segmented scene without "re-meshi...
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In order to display huge scenes with virtual human inhabitants evolving inside a virtual city, we propose a methodology to create and manage different levels of detail for a well-segmented scene without "re-meshing" the scene during simulation. A database dedicated to urban life simulation, providing data for planning human actions and behaviour, is completed such a way to furnish information about the most adapted displayed representations.
The display of iso-surfaces in medical data sets is an important visualization technique used by radiologists for the diagnosis of volumetric density data sets. The demands put by radiologists on such a display techni...
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The display of iso-surfaces in medical data sets is an important visualization technique used by radiologists for the diagnosis of volumetric density data sets. The demands put by radiologists on such a display technique are interactivity, multiple stacked transparent surfaces and cutting planes that allow an interactive clipping of the surfaces. This paper presents a Java based, platform independent implementation of a very fast surface rendering algorithm which combines the advantages of explicit surface representation, splatting, and shear-warp projection to fulfill all these requirements. The algorithm is implemented within the context of J-Vision, an application for viewing and diagnosing medical images which is currently in use at various hospitals.
We show how the mass properties of an articulated body, such as its center of mass and its moments of inertia, may be manipulated like any conventional end effector with well-known iterative, numerical techniques. Wit...
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We show how the mass properties of an articulated body, such as its center of mass and its moments of inertia, may be manipulated like any conventional end effector with well-known iterative, numerical techniques. Within our interactive simulation testbed software, we illustrate this tool for the geometrical design of rigid bodies with prescribed mass properties, and for the manipulation of human figures in computer animation.
Current virtual reality technologies provide many ways to interact with virtual humans. Most of those techniques, however, are limited to synthetic elements and require cumbersome sensors. We have combined a real-time...
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Current virtual reality technologies provide many ways to interact with virtual humans. Most of those techniques, however, are limited to synthetic elements and require cumbersome sensors. We have combined a real-time simulation and rendering platform with a real-time, non-invasive vision-based recognition system to investigate interactions in a mixed environment with real and synthetic elements. In this paper, we present the resulting system, the example of a checkers game between a real person and an autonomous virtual human to demonstrate its performance.
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