Global illumination is an important factor when striving for photo realism in computergraphics. This thesis describes why this is the case, and why global illumination is considered acomplex problem to solve. The problem becomes even more demanding when considering realtime purposes. Resent research has proven it possible to produce global illumination in realtime. Therefore the subject of this thesis is to compare and evaluate a number of those methods. An implementation is presented based on the Imperfect shadow maps method, which per se isbased on instant radiosity and reflective shadow maps. The implementation is able to renderplausible global illumination effects in real time, for fully dynamic scenes. With conclusions that while it demonstrably is possible to provide believable global illum-ination in real time, it is not without shortcomings. In every case approximations or restrictionshas to be done to some extent, sometimes leading to wrong results. Though in most cases, notvisually unpleasing by a great deal. The final conclusion is that global illumination is possible on current hardware, with believablequality and good speed. Showing great potential for future implementations on next generationof hardware.

Nowadays, 3D rendering has been widely applied in video games. Every year companies strive to come up with new solutions and implementations that potentially will increase the complexity of an algorithm, combined with trying to improve the realism of the graphics. An algorithm called Cascaded Shadow Maps will be compared and experimented upon with a regular Shadow Maps algorithm. To further provide information regarding the subject at hand. Objectives. The aim of this experiment is to implement Shadow Maps and Cascaded Shadow Maps in Unity and compare said algorithms to each other. Furthermore, come to a conclusion of which algorithms perform better. Data that will be researched is the Frame rate, Memory consumption, RAM, and Total memory used with the help of Unity's built-in tools. Methods. Shadow Maps and Cascaded Shadow Maps were implemented in Unity Engine by the following literature. Additionally, with help of built-in tools from unity, the Unity Profiler Module. It was possible to take measures to compare each technique of said data. The data were collected five times and then calculated into an average number. Resulting in a collection of data structured and displayed with graphs. Lastly, analyses were performed based on collected data. Results. The data measured and compared showed that Shadow Maps were superior to Cascaded Shadow Maps regarding frame rate, memory consumption, and total memory used. However, Cascaded Shadow Maps could be considered as a algorithm with better complexity to quality ratio than Shadow Maps.  Conclusions. It is Concluded that the Cascaded Shadow Maps utilizes more resources, having less frame rate, higher memory consumption and total memory used. However, Cascaded Shadow Maps were proven in some cases to have better complexity to quality ratio. Additionally, Cascaded Shadow Maps solves the problem Shadow Maps creates, Aliasing. Leads to well-rounded and improved shadows for realism with Cascaded Shadow Maps and in some cases at a small cost.

This paper concerns aliasing removal methods during the shadow displaying. Method of shadow mapping, its principles, procedure and mainly its drawbacks in the form of aliasing development are described. For the removal of this undesirable phenomenon, several aliasing suppressing methods are described - Percentage Closer Filter, Variance Shadow Map, Convulotion Shadow Map, Exponential Shadow Map a Bilateral Filter. I conclude my work with a proposal and implementation of a demonstrative application, which demonstrates the implemented results adequately. Also, the comparison of individual methods on the basis of their quality and computational demands is included.

Background To be able to push game standards further and further, different graphics techniques have to be implemented by game developers. By utilizing some of those techniques, comes cost in the form of performance issues. Level of detail (LOD) is an optimization technique which uses several different variations of a model and distance from the viewer to determine which model should be rendered. Shadow mapping is, on the contrary from level of detail, a costly technique which aims to create as realistically looking shadows as possible. Objectives The aim of this thesis is to examine whether a novel LOD technique and shadow map technique called LOD-SM can achieve less render time versus using a standard implementation of shadow mapping. This is achieved by using the Unity game engine in which the LOD-SM technique is implemented. With Unity, measurements will be taken to determine if the technique is a viable optimization option in future game development. Methods The methods used to answer the paper’s research question were a pilot user study and a performance study. 20 participants were part of the pilot study, and were asked to rate their perception of shadows shown on a screen in front of them. This yielded results of which shadows the participants noticed differences for. The results were then implemented into Unity and measured with the LOD-SM technique. Results The pilot study showed that user does not notice any differences in 30% decreased polycount-shadows when in a multiple building environment. The gathered results from the performance experiment showed that the LOD-SM technique saved between ∼17% up to ∼70% in render time, compared to a regular implementation of shadow mapping. Conclusions In conclusion, a viable optimization option was found which is to lower a shadow maps appearance based on buildings LODs because as the results has shown, users does not notice the lowering of LODs up to 30% when in a multiple building area. It was discovered that by measuring the LOD-SM technique, clear evidence of optimization was found when using the technique versus using a normal implementation of shadow mapping. Developers would have to consider the size of project and its models before implementing the LOD-SM technique, as it might not be viable for projects with a total polycount of less than 100 000 polygons.

This thesis deals with problem of computation of global illumination in real-time. Two methods are described. Namely Reflective Shadow Maps and Light Propagation Volumes. The first of them deals with the problem by using extended Shadow Mapping algorithm. The second one uses scene embedded into a 3D grid together with Spherical harmonics to compute light propagation in the scene. Furthermore this thesis contains results of measurement of the rendering speed of the Light Propagation Volumes algorithm with various settings on several machines. Quality of the resulting output of the algorithm is also evaluated.

Šiame darbe pateikiamas apšvietimo algoritmas pusiau skaidriems, vientisiems kūnams, kai šviesos sklidimas gali būti išreikštas BTDF, algoritmas pritaikomas spalvotiems šešėliams. Jis yra realaus laiko, ir gali būti pilnai realizuojamas šiuolaikiniuose trimačio vaizdo spartintuvuose. Algoritmas suskaido vaizduojamą objektą į sluoksnius ir kiekviename sluoksnyje saugo informaciją apie tai, kiek šviesos sugeriama tame sluoksnyje, ir kokioje pozicijoje spindulys atsitrenkė į matomą objekto paviršių. Konkretaus taško piešimo metu imama informacija iš atitinkamo sluoksnio (peršviečiamumo žemėlapio) ir šviesos sugėrimo stiprumas tiesiškai interpoliuojamas tarp skirtinguose žemėlapiuose saugomų atstumų. / This thesis focuses on partially transparent objects lighting, where light distribution may be written in BTDF1, algorithm supports multi-colored shadows. It is real-time method and can be fully implemented in modern graphics hardware. Algorithm divides object into layers, in each of them is stored information about how much light is absorbed in that layer, and where light hit visible object surface. On rendering particular point we take appropriate layer (opacity map) and light absorption intensity is linearly interpolated between different distances stored in other opacity maps.

This thesis is focused on describing methods of computation of global illumination of 3D graphics scenes in real-time. First chapter contains brief introduction to the issue of global illumination (GI) computation, as well as quick summarisation of principles of most commonly used GI computation approaches. A method of visibility computing for indirect illumination, taking advantage of Imperfect Shadow Mapping, is introduced next. After closer examination of this method and prerequisite algorithms follows a description of its practical implementation, as well as of the structure of simple demonstrative application. Next chapter then contains testing and brief examination and evaluation of resulting program's behaviour. Finally, a possible method extension by means of virtual point light clustering is proposed.

Cílem této práce je prezentovat metody pro akceleraci výpočtů stínů a osvětlení.  Práce se zabývá akcelerací na vzorek přesných stínů pomocí stínových těles na různých platformách. Obsahem práce je také zvýšení přesnosti stínových map a zvýšení přesnosti osvětlování scény s mnoha světly.

Rendering shadows of transparent objects in real-time applications is difficult. The number of usable methods is limited by the available computing power. Depth Peeling and Dual Depth Peeling methods are described in this document. These allow rendering of transparent objects without the need of sorting them. Deep Shadow Maps are described as a method for rendering shadows of transparent objects. These methods were used to create an demonstration application. This application provides rendering of transparent objects and their shadows, including colored ones. The Application is build upon OpenGL and Qt framework. Evaluation of rendering speed according to various parameters is also part of this work.

V interaktivních aplikacích jsou stíny tradičně zobrazovány s pomocí algoritmu založeným na stínových mapách. Nevýhodou toho algoritmu je, že stínová mapa, reprezentovaná texturou, má pouze omezené rozlišení. To může vést k nepěkným vizuálním artefaktům objevujících se na hranách stínů. Tato práce představuje postup, který je založen na vylepšené deformaci textury. To umožní zobrazit scénu obsahující složité světelné zdroje, zredukovat artefakty na hranicích stínů a také vylepšit kvalitu stínů bez ohledu na typu scény a její konfiguraci.