The problem of estimating an adequate level of detail for an object for a specific view is one of the important problems in computer 3d-graphics and is especially important in real-time applications. The well-known continuous level-of-detail technique, Real-time Optimally Adapting Meshes (ROAM), has been employed with success for almost 10 years but has at present, due to rapid development of graphics hardware, been found to be inadequate. Compared to many other level-of-detail techniques it cannot benefit from the higher triangle throughput available on graphics cards of today. This thesis will describe the implementation of the new version of ROAM (informally known as ROAM 2.0) for the purpose of massive planetary data visualization. It will show how the problems of the old technique can be bridged to be able to adapt to newer graphics card while still benefiting from the advantages of ROAM. The resulting implementation that is presented here is specialized on spherical objects and handles both texture and geometry data of arbitrary large sizes in an efficient way.

Thesis describes programming of 3D applications, mainly games, on Windows Phone 7 platform and lightly compares this approach with Silverlight platform. It also describes XNA framework in detail and programming plane simulators problems. In the second part of this thesis, reader can find complete description of implementation of a simple airplane simulation for Windows Phone 7 platform, which is based on the XNA framework. The game consists of implementation of terrain, sky, plane, scene and also of physics and the principle of the game.

Work discusses rendering of complex scenes and terrain. It's main task is to show the extensive scenery terrain that normally do not fit in the graphic card memory. It introduce the theory of terrain rendering including terrain level of detail algoritms. The paper presents the design and implementation of application that implements dynamic streaming of complex terrain.

Parallel, adaptive Level-of-Detail in VR simulations. Parameters for efficient reuse of already calculated reductions are investigated. Choosen reduction algorithms are evaluated. Parameters for communication within the distributed application are determined. An implementation is introduced. / Paralleles, adaptives Level-of-Detail komplexer Objekten in VR-Simulationen. Die Parameter für eine effiziente Wiederverwendung bereits berechneter Reduktionen werden untersucht. Ausgewählte Reduktionsalgorithmen werden evaluiert. Die Parameter für die Kommunikation in der verteilten Applikation werden ermittelt. Eine Implementation wird vorgestellt.

Level of Detail (LOD) is an important area in game development and it is a term used to describe the complexity of 3D models. Complex 3D models that are rendered from a far distance can often be simplified, to minimise rendering costs. The visual appearance of a simplified model should be as close to the original model as possible. This process requires metrics that can produce a similarity score or a distance value between meshes of different quality.  In this report, four different metrics are evaluated on a dataset with models of different qualities. The metrics are the MSDM2, Chamfer Distance, Hausdorff Distance and Simplygon's internal distance called Maximum Deviation. The dataset is already annotated with subjective scores from an earlier experiment, and the metrics are evaluated using the Spearman and the Pearson Correlations between metric values and subjective scores. The metrics are evaluated on the whole model set, and on different categories of models. The correlation scores are calculated using three different regression techniques. These are a per-dataset regression, a scaled per-dataset regression, and an averaged per-model regression. In addition to this, the metrics are also evaluated on the same dataset but where the LOD:s are created using a different simplifying algorithm, Simplygon's own reducer.  The results show that MSDM2 is the best metric in correlation with subjective scores when using a per-dataset regression. It is also noticed that the other metrics are all quite similar. The difference between the MSDM2 metric and the other metrics is also much larger on categories like "Hard surface"- and "Complex" models. When using the less common regression techniques, MSDM2 has the worst correlation, and Chamfer Distance correlates the best.  When comparing the results from the two datasets, Simplygon's own reducer seem to have a greater correlation with the MSDM2 metric. There was no clear difference in scores for the other metrics.  The end result is that one metric is not always the best metric. The type of model, and the simplification algorithm used to create the LOD, can both affect the result. The evaluation technique also changes the result.

The thesis deals with the concept of level of detail and its use in 3D GIS. The aim of this work is to design a data structure that will allow continuous rendering of discrete 3D building models with different levels of geometric detail, which were created by generalization method based on mathematical morphology approach. The proposed solution creates links of corresponding geometric primitives of models at different level of detail at first and then reconstructs them using the extrusion method. The data structure created in this way is able to generate and render any model, including intermediate models, which are represented as slices through the data structure across the axis of geometric detail.

Introduction – The building industry is evolving, this urges for innovative methodologies to facilitate the construction processes including the information exchanges between these to accomplish a sustainable future. In addition, new requirements are being set by the Swedish government and other national authorities with the objective of reducing the climate impact caused by the construction industry, which is responsible for a large amount of carbon dioxide emissions. A helpful tool to estimate the total carbon dioxide emission value is the Life Cycle Analysis (LCA) which depends on the Information Exchanges (IE) and the Level of Development (LOD) in BIM (Building Information Modelling) based projects to achieve a reliable result. Therefore, this research aims to find a better understanding of the relation between LOD, IE and LCA in BIM-based projects. Method – This research is based on an authentic ongoing construction project (casestudy), an assembled theoretical framework based on knowledge of the different subjects: LOD, BIM, LCA and IEs. And how previous researchers have faced similar issues. Also, on various thorough document analysis (BIM model and EIs) obtained from the case study. The mentioned above forms a support basis for this paper. Results – Two different BIM models were used to perform two LCA-simulations. One formed with LOD 200 provided a generic presentation of the studied element, which in this case was the model’s exterior walls. While the other model with LOD 300 generated a complex presentation of the model’s exterior walls. The simulation generated a comparative data showing that the Low LOD model had a climate impact value of 248 000 kg CO2. On the other hand, the High LOD model generated a climate impact value of 137 850 kg CO2, resulting in a 45% difference. The results presents that a lower carbon dioxide emission was caused when utilizing a higher LOD which contains more complex and specific information. The results argue for that a BIM model with the adequate amount of LOD is crucial for obtaining more reliable results when performing an LCA. Analysis – The results obtained from the LCA-simulations enhance the theories about the importance of LOD when performing an LCA. Higher LOD in a model generates more reliable results. Moreover, using a BIM software and an LCA plugin as tools facilitate the various IEs in a project. Discussion – The approach was limited to explore the environmental impact of one construction element, exterior walls, and its different LOD. Also, only the stage A1-A3 was analysed. However, trustworthy results were obtained due to the use of reliable data and research methods.

Real-time rendering of large-scale terrains is a difficult problem and remains an active field of research. The massive scale of these landscapes, where the ratio between the size of the terrain and its resolution is spanning multiple orders of magnitude, requires an efficient level of detail strategy. It is crucial that the geometry, as well as the terrain data, are represented seamlessly at varying distances while maintaining a constant visual quality. This thesis investigates common techniques and previous solutions to problems associated with the rendering of height field terrains and discusses their benefits and drawbacks. Subsequently, two solutions to the stated problems are presented, which build and expand upon the state-of-the-art rendering methods. A seamless and efficient mesh representation is achieved by the novel Uniform Distance-Dependent Level of Detail (UDLOD) triangulation method. This fully GPU-based algorithm subdivides a quadtree covering the terrain into small tiles, which can be culled in parallel, and are morphed seamlessly in the vertex shader, resulting in a densely and temporally consistent triangulated mesh. The proposed Chunked Clipmap combines the strengths of both quadtrees and clipmaps to enable efficient out-of-core paging of terrain data. This data structure allows for constant time view-dependent access, graceful degradation if data is unavailable, and supports trilinear and anisotropic filtering. Together these, otherwise independent, techniques enable the rendering of large-scale real-world terrains, which is demonstrated on a dataset encompassing the entire Free State of Saxony at a resolution of one meter, in real-time.

An image is a set of quantized intensity values that are sampled at a finite set of sample points on a two-dimensional plane. Images are crucial to many application areas, such as computer graphics and pattern recognition, because they discretely represent the information that the human eyes interpret. This thesis considers the use of triangular meshes for approximating intensity images. With the help of the wavelet-based analysis, triangular meshes can be efficiently constructed to approximate the image data. In this thesis, this study will focus on local image enhancement and mesh simplification operations, which try to minimize the total error of the reconstructed image as well as the number of triangles used to represent the image. The study will also present an optimal procedure for selecting triangle types used to represent the intensity image. Besides its applications to image and video compression, this triangular representation is potentially very useful for data storage and retrieval, and for processing such as image segmentation and object recognition. / Master of Science

In dieser Arbeit wird ein applikationsunabhängiges Reduktionssystem entworfen, das selbstständig und effizient für die ihm übergebenen Modellteile in allen Betrachtersituationen aus einem möglichen Spektrum von geometrie- und bild-basierten Approximationsformen jeweils die geeignete Approximation generiert, deren Komplexität möglichst gering ist und bei deren Verwendung ein Szenenbild erzeugt werden kann, dessen Bildfehler die vom Nutzer vorgegebenen Schranken nicht überschreitet. Das System nutzt bild- und geometrie-basierte Approximationsformen für unterschiedliche Bereiche im Sichtvolumen des Betrachters. Nailboards sind die benutzten bild-basierten Approximationen. In dieser Arbeit werden neue Nailboardarten vorgestellt, die für die Approximation von semi-transparenten Objekten und von dynamisch beleuchteten Objekten effizient verwendet werden können. Die vorgestellten Erzeugungs- und Darstellungsmethoden nutzen die Fähigkeiten der aktuellen Hardware intensiv aus, um die Nailboards im Echtzeitkontext nutzbar zu machen. Texturierte, sichtabhängige geometrie-basierte Approximationen werden aus einem texturierten Viewdependent Progressive Mesh (VDPM) gewonnen. In dieser Arbeit wird eine effiziente Methode zur Erzeugung von VDPM vorgestellt, aus der Approximationen mit optimal angepassten Parameterkoordinaten gewonnen werden können, ohne dass ein der VDPM-Erzeugung nachgeschalteter Optimierungsschritt der Parameterkoordinaten aller im VDPM kodierten Approximationen notwendig ist. Die Erzeugung der notwendigen Texturen erfolgt unter Nutzung einer schnellen Parametrisierungsmethode und hardware-gestützter Methoden zur Erzeugung dicht gepackter Texturatlanten. Durch die Kombination von selektiven Zugriffsmethoden auf TFGR mit effizienten Randanpassungsmethoden, wird erstmals ein effizientes und qualitativ hochwertiges Multiresolution Rendering mittels TFGR ermöglicht. Aus dem TFGR werden texturierte sichtunabhängige Approximationen gewonnen. Zur echtzeitfähigen, vollautomatischen Erzeugung aller drei Approximationsformen wird in dieser Arbeit ein Reduktionssystem vorgeschlagen, das diese Approximationsformen verteilt generiert. Für eine effiziente Kommunikation innerhalb dieses Systems werden entsprechende Kompressions-, Caching- und State-Differencing-Mechanismen vorgeschlagen. Lastverteilungsmechanismen sichern eine effiziente Ausnutzung der zur Verfügung stehenden Ressourcen ab. / In this thesis, an application-independent system for the distributed generation of object approximations used for multi-resolution rendering is proposed. The system generates approximations of objects of a scene sent to him in an efficient and fully automatic manner. The system is able to generate different kinds of geometry-based and image-based object approximations. For each given objects of a scene it generates that kind of approximation that is suitable for the current view. That means that its complexity is minimal and that it causes an error in the image generated with this approximation that does not exceed a user-specified threshold. Nailboards are image-based approximations that approximate objects whose size is small compared to the whole scene. In this thesis new kinds of nailboards are presented which can be used efficiently for the approximation of semi-transparent objects and objects in scenes with a dynamic illumination. Capabilities of current graphics hardware are intensively used to generate and render all kinds of Nailboards in real-time. So-called textured view-dependent progressive meshes (VDPM) are used as view dependent geometry-bases approximations for objects whose size is large compared to the whole scene. In this thesis an efficient method for generating VDPM is presented. This method allows the extraction of approximations with optimally adapted texture coordinates without the necessity of an separate optimization step for the texture coordinates in the generation procedure. The textures necessary for the compensation of detail loss are generated using a fast parameterization method from Yoshizawa. The generation of texture atlases is done hardware-accelerated. Further on a hardware-accelerated method for hardware-accelerated multi-resolution rendering using multi chart geometry images (MCGIM) is presented. Out of the MCGIM view-independent geometry-based approximations are extracted. Finally a system for the distributed generation of object approximations is proposed. It generates all three kinds of approximations fully automatic and almost in real time. For an efficient communication within this system suitable compression, caching and state-differencing mechanisms are proposed. Load balancing mechanisms ensure efficient utilization of available resources.