This thesis focuses on the design and implementation of a software system enabling out-of-core rendering of multiple map datasets mapped on virtual globes around our solar system. Challenges such as precision, accuracy, curvature and massive datasets were considered. The result is a globe visualization software using a chunked level of detail approach for rendering. The software can render texture layers of various sorts to aid in scientific visualization on top of height mapped geometry, yielding accurate visualizations rendered at interactive frame rates. The project was conducted at the American Museum of Natural History (AMNH), New York and serves the goal of implementing a planetary visualization software to aid in public presentations and bringing space science to the public. The work is part of the development of the software OpenSpace, which is the result of a collaboration between Linköping University, AMNH and the National Aeronautics and Space Administration (NASA) among others.

This report covers theory and comparison of techniques for rendering massive scale 3D geospa- tial planet data in a web browser. It also presents implementation details of a few of these tech- niques in WebGL and Javascript, using the Three.js [1] 3D library. The thesis project is part of the implementation of Unitea, a web based education platform for interactive astronomy visualizations. Unitea is a derivative of Uniview, which is a fulldome interactive simulation of the universe. A major part of this thesis is dedicated to the implementa- tion of Hierarchical Level of Detail (HLOD) modules for Three.js based on the theory presented by T. Ulrich [2] and later generalized by Cozzi and Ring [3]. HLOD techniques are dynamic level of detail algorithms that represent the surface of objects as accurately as possible from a certain viewing angle. By using space partitioning tree-structures, view based error metrics and culling techniques detailed representations of the objects (in this case planets) can be efficiently rendered in real-time. The modules developed provide a general-purpose library for rendering planets (or other spher- ical objects) with dynamic level of detail in Three.js. The library also features connections to online web map services (WMS) and tile services.

Present graphic requires a lot of optimizations of rendering techniques and mathematical calculations. It is caused by increased requirements of scene's visualization. One of scene's optimizing techniques is the Level of detail. This thesis is focused on methods used by LOD in OpenSceneGraph and OpenGL library. Next it will be described how to choose the right level of detail in a scene. Later it will be explained how to simplify 3D models. These techniques will be implemented in converting tool and demonstrating application. Methods for simplify 3D models will be tested for their speed and quality.

This thesis introduces a representation of graphical data, progressive meshes, and its fields of usage. The main part of this work is mathematical representation of progressive meshes and the simplification algorithm, which leads to this representation. Examples of changes in progressive mesh representation are also part of this thesis, along with few examples. The result is an application that implements the calculation of the Progressive Meshes model representation

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.

Level of detail (LOD) systems has long been a central concept within the field of computer graphics. By selectively allocating detail only to where it is necessary, the cost of rendering virtual objects can be greatly decreased. The usefulness of an LOD system is closely tied to the metrics used to evaluate how to distribute detail, as getting these wrong can lead to visual artifacts or rendering detail which is not visible to an observer. To offset this, researchers have investigated how we can optimize these systems by leveraging human perception to allocate detail based on if the detail is perceivable. This paper explores the use of LOD systems in the context of virtual terrains, a common use case were LOD systems have seen much prior use, and delves into how such systems can be optimized further by leveraging human perception. The paper presents a method centered around the use of octrees, a data structure used to partition and compress volumetric data, alongside spatial frequency, a concept related to human perception which provides insight into where visual stimulus borders on being percievable, to dynamically generate transition distances for an LOD system. The presented method is evaluated using a terrain generator created in the Unity engine alongside Nvidia ꟻLIP, a tool for evaluating differences in images based on human perception metrics. Results indicate that the presented method did lead to a decrease in resource cost when generating terrain when compared to some other methods while the ability to optimize LOD transition distances based on silhouette-background contrast remains uncertain. / Nivå av detalj (LOD) system har länge varit ett centralt begrepp inom forskningsområdet för dator-grafik. Genom att selektivt allokera detalj så kan kostnaden för att rendera virituella föremål minskas drastiskt. Användbarheten av ett LOD-system är nära kopplat till de specifika värden som används för att utvärdera hur man fördelar detalj efterssom man annars riskerar att få virtuella artefakter eller renderar detaljer som inte är synliga för en observatör. För att motverka detta har forskare undersökt hur vi kan optimisera dessa system genom att utnyttja visuell uppfattning hos människor för att allokera detalj baserat på var den är synlig för användaren. Denna text utforskar användningen av LOD-system i samband med virtuella terränger, ett användningsområde där LOD-system har använts tidigare och går in på hur denna typ av system kan optimiseras bättre genom att utnyttja mänsklig perception. Texten presenterar en metod centrerad runt användandet av octrees, en datastruktur som används för att partitionera och komprimera volumetrisk data, tillsamans med spatiell frekvens, ett koncept relaterat till mänsklig synförmåga som ger inblick i var visuell stimulans gränsar till att vara synlig, för att dynamiskt generera övergångsavstånd för ett LOD-system. Den presenterade metoden utvärderas med en terränggenerator skapad i Unity spel-motorn tilsamans med Nvidia ꟻLIP, ett verktyg för att utvärdera skillnader i bilder baserat på mänskliga perceptionsmått. Resultaten indikerar att den presenterade metoden ledde till en minskning av resurskostnaden vid generation av terräng jämfört med vissa andra metoder medan möjligheten att optimera övergångsavstånd för LOD-systemet baserat på kontrast mellan bakgrunden och silouetten för terrängen kvarstår som osäker.

The purpose of the study was to explore how property management companies view of Building Information Modeling (BIM) as a working method in property management process, and to explore the companies efforts at BIM in terms of the level of detail on BIM object implementation in property management. The study includes both companies that have and do not have contributions in BIM. The exploration was aimed at two companies and their varying ways of working to inform the needs of BIM in property management. The purpose of the study was also to give a clear picture of how BIM tools should be defined in the management process. The work was used of qualitative methods to answer the questions first consisted of a literature review, interviews and case study. The case study was about BIM implementation in New Karolinska Solna. The result showed that the definition of BIM in property management companies is not clear yet. The companies have intended to use BIM, but they are not there yet, there should be a type of requirements list that works with planning and production and benefit from using BIM in the property management. According to respondents, most of the common reasons why BIM was not used were because the approach of the tool. There is no proper structure or common working method of how the tool would be applied. Many literature sources including respondents claimed that BIM seemed good and have a good potential to be the future work process. BIM leads to improved work environment, improved sustainability development, good marketing, increased quality in work, time savings, and improved project management. As a suggestion as to how BIM could be implemented, it can be described in a few steps, which is status analysis, identify the benefits of BIM, start implementing on a smaller scale, follow up continuously, improve and expand the work and last but not least Integrate information. The conclusions that can be drawn from the results and literature study were that BIM can improve the quality management of the properties, but it is important to find a reasonable level of BIM implementation as well as a suitable detail level of BIM-model.

VYSOKÉ UČENÍ TECHNICKÉ V BRNĚ The purpose of this work is to design and implement a computer system, which should be used for simplification of a polygonal models in 3D space. The system should be allowed to reduce a given number of geometrical primitives from source object. User should have impact to the reducing process by selecting a method, size of target object etc. System uses 3DS file format for model loading and saving. Reader should understand principles of the polygon reduction and used algorithms.