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BIM, Building Information Modelling, är inget nytt begrepp för byggbranschen och ämnet är välutforskat i teorin. Den praktiska tillämpningen har dock inte nått ut till hela den svenska branschen och lägst implementation finns idag hos förvaltningen. För att BIM ska nå ut till denna del av branschen, behöver beställarna förstå vilken funktion BIM kan bistå med och ställa BIM-krav i sina projekt. Då det inte finns någon övre gräns på hur mycket information en modell kan innehålla, behöver beställarna också definiera vilken information som är nödvändig för sökta funktioner. Denna studie ämnar att tydliggöra hur informationsinnehållet i en modell påverkas av olika detaljeringsnivåer. Genom en sammanställning av befintliga standarder och nivåsystem har en utbildningslokal på 150kvm modellerats med hjälp av Autodesk Revit Architecture. Med hjälp av denna modell och sammanställd teori dras följande slutsatser. Det är möjligt att säkerställa informationsbehoven hos beställarens organisation med hjälp av ett detaljeringsnivåsystem. Olika fastigheter har olika funktionsbehov och kräver olika detaljeringsnivåer. En generell nivå på vilken information som ska ingå i dessa modeller borde gå att fastställa. En förutsättning för lyckade BIM-projekt är att tydliga anvisningar och krav upprättas inför modellering och att dessa är förankrade i byggprojektets och förvaltningens informationsbehov. / BIM, Building Information Modelling, is not a new concept for the construction industry and the subject is well reviewed in theory. The practical application has not yet reached out to the whole Swedish construction industry and the lowest implementation of BIM can be found in facility management. For BIM to reach this part of the industry, clients’ needs to understand the functions that BIM can assist with and set BIM requirements for their projects. Since there is no upper limit on the level of information a model may contain, clients also needs to define which information is necessary for the sought functions. This study aims to clarify how the information content of a model is affected by different levels of detail. Through a compilation of existing standards and level system has an education facility of 150sqm been modeled using Autodesk Revit Architecture. With the help of this model and the compiled theory, following conclusions has been drawn. It is possible to ensure the information needs of the client's organization with the help of a system for level of development. Different buildings have different functional needs and require different levels of detail. A general level of detail to be included with these models should be possible to determine. A prerequisite for successful BIM project is that clear instructions and requirements are established for the modeling process and that these are anchored in the needs of the project and management.

<p>This thesis is focused on the improvement of an existing implementation of a waveform visualizer. The problem area handled in this work has its focus on how to reduce the number of points to be plotted. The given waveform visualizer was extended by the use of two additional algorithms. First, a Level Of Detail (LOD) algorithm that gives the subset of points that are necessary to plot the waveform in the current zoom level. Second, a straight line identification algorithm to find a series of points aligned in a straight line, only leaving the end points and then drawing a line between them. These two optimizations are the main focus of this work.Additionally, an exporting functionality was implemented to export the plot data into several different data formats. Also some improvements of zooming, panning, some GUI design, and a new drag and drop functionality was constructed.</p>

In recent years, multiresolution models have progressed substantially. At the beginning, discrete models were employed in graphics applications, due mainly to the low degree of complexity involved in implementing them, which is the reason why nowadays they are still used in applications without high graphics requirements. Nevertheless, the increase in realism in graphics applications makes it necessary to use multiresolution models which are more exact in their approximations, which do not call for high storage costs and which are faster in visualization. This has given way to continuous models, where two consecutive levels of detail only differ by a few polygons and where, additionally, the duplication of information is avoided to a considerable extent, thus improving on the spatial cost offered by most discrete models.Advances have been made in the use of new graphics primitives which minimize the data transfer between the CPU and the GPU, apart from trying to make use of the connectivity information given by a polygonal mesh. For this purpose, graphics primitives with implicit connectivity, such as triangle strips and triangle fans, have been developed. Many continuous models based on this type of primitives have been recently developed. In these last few years, graphics hardware performance has evolved outstandingly, giving rise to new techniques which allow the continuous models to accelerate even more. In this work, we have improved the interactive render of polygonal meshes. To tackle the problem, we firstly studied fundamental techniques to efficiently render polygonal meshes and we later made use of geometry simplification and level of detail techniques. Thus, we defined a multiresolution model that represents a polygonal mesh at any given resolution. This approach is able to manage continuous level-of-detail by smoothly adapting mesh resolution to the application requirements. Moreover, the model was modified to take the maximum advantage of the recent GPU features. We also created a modified version of the model for being used in deforming meshes. Finally, we developed an independent library to integrate our model in real-time applications.

Background. Level of detail is an optimization technique used by several modern games. The level of detail systems uses simplified triangular meshes to determine the optimal combinations of 3D-models to use in order to meet a user-defined criterion for achieving fast performance. Prior work has also pre-computed level of detail settings to only apply the most optimal settings for any given view in a 3D scene. Objectives. The aim of this thesis is to determine the difference in image quality between a custom level of detail pre-preprocessing approach proposed in this paper, and the level of detail system built in the game engine Unity. This is investigated by implementing a framework in Unity for the proposed level of detail pre-preprocessing approach in this paper and designing representative test scenes to collect all data samples. Once the data is collected, the image quality produced by the proposed level of detail pre-preprocessing approach is compared to Unity's existing level of detail approach using perceptual-based metrics. Methods. The method used is an experiment. Unity's method was chosen because of the popularity of the engine, and it was decided to implement the proposed level of detail pre-preprocessing approach also in Unity to have the most fair comparison with Unity's implementation. The two approaches will only differ in how the level of detail is selected, the rest of the rendering pipeline will be exactly the same. Results. The pre-preprocessing time ranged between 13 to 30 hours. The results showed only a small difference in image quality between the two approaches, Unity's built-in system provides a better overall image quality in two out of three test scenes. Conclusions. Due to the pre-processing time and no overall improvement, it was concluded that the proposed level of detail pre-preprocessing approach is not feasible.

Context. The geometric complexity of objects in games and other real-time applications is a crucial aspect concerning the performance of the application. Such applications usually redraw the screen between 30-60 times per second, sometimes even more often, which can be a hard task in an environment with a high number of geometrically complex objects. The concept called Level of Detail, often abbreviated LoD, aims to alleviate the load on the hardware by introducing methods and techniques to minimize the amount of geometry while still maintaining the same, or very similar result. Objectives. This study will compare four of the often used techniques, namely Static LoD, Unpopping LoD, Curved PN Triangles, and Phong Tessellation. Phong Tessellation is silhouette-based, and since the silhouette is considered one of the most important properties, the main aim is to determine how it performs compared to the other three techniques. Methods. The four techniques are implemented in a real-time application using the modern rendering API Direct3D 11. Data will be gathered from this application to use in several experiments in the context of both performance and image space metrics. Conclusions. This study has shown that all of the techniques used works in real-time, but with varying results. From the experiments it can be concluded that the best technique to use is Unpopping LoD. It has good performance and provides a good visual result with the least average amount of popping of the compared techniques. The dynamic techniques are not suitable as a substitute to Unpopping LoD, but further research could be conducted to examine how they can be used together, and how the objects themselves can be designed with the dynamic techniques in mind.

In this paper a method to automatically generate transition distances for LOD, improving image stability and performance is presented. Three different methods were tested all measuring the change between two level of details using the spatial frequency. The methods were implemented as an optional pre-processing step in order to determine the transition distances from multiple view directions. During run-time both view direction based selection and the furthest distance for each direction was tested in order to measure the performance and image stability. The work was implemented in the Frostbite game engine and tested using data from DICE. The result is a method that generates transition distances by calculating the spatial frequency of the exclusive or comparison between the silhouette of a ground truth mesh and each level of detail. The transition distances generated using the automatic LOD selection tool was evaluated using visual empirical tests and performance measurements comparing the performance of a scene using automatic generated distances and manually selected distances. The tests shows that the resulting method produces good transition distances for meshes where the reduction is visible in the mesh silhouette. The values might need a bit of tweaking in order to account for other image artifacts than silhouette changes but provide a good guidance to the artists.

Genom nya utvecklade standarder så spås webben i framtiden alltmer utgöra en fullgod applikationsplattform. HTML5 skapar bland annat möjligheten att använda sig av vektorgrafik genom Canvas-API. Användningen av vektorgrafik kräver dock lokal rendering och på en resurssvag enhet kan detta innebära att displayens framerate sjunker. Användaren upplever "lagg" och för många applikationer är detta negativt för användbarheten. För att webbapplikationer ska kunna fungera tillfredställande för en stor bredd av enheter med varierande kapacitet är det fördelaktigt att användningen av grafik sker adaptivt. Detta arbete undersöker om användningen av progressiv detaljrikedom i Canvas-grafik kan bidra till att hålla framerate uppe vid tillämpning på mobila enheter. Resultaten pekar som väntat på att reducerade detaljnivåer samt att byta ut bezierkruvor mot linjer ger förbättrad fps, men att utfallen varierar mellan olika webbläsare och telefonmodeller.

This master thesis deals with the large terrain rendering in real time using WebGL. The thesis also deals with ways of measuring and representation of terrain height data. The paper also compares several frameworks for WebGL and also describes the practical use of HTML5 technologies such as WebWorkers. Furthermore, it also compares the performance and compatibility of current web browsers with HTML5 technologies.