this report is therefore to present an overview of the current state of the art in realtime rendering of trees. Given our goal to increase the overall realism of computer generated scenes, the algorithms we have examined focus on realistic rendering of trees. There is of course research on achieving non-realistic e#ects such as sketch outlines, hatched shading, etc., but these methods are outside the scope of this paper (see, for example, Deussen's book for a good overview [8]). In addition to presenting each algorithm, we will summarize the advantages and drawbacks in a separate section

Analysis of medical images is resource demanding and time-consuming, and automatic procedures are needed to reduce the workload of medical staff in a pre-operative planning phase. In this thesis, the main focus has been on methods that automatically segment CT and MR volume data, in particular new approaches for representation and segmentation of the liver, hepatic vessels and the kidney. The two main contributions in this thesis are a new 3D skeleton procedure and a texture-based segmentation method. The skeleton procedure is iterative, without user-defined parameters, and produces a minimalistic representation of binary objects without known artifacts. Compared to previous work, this skeleton method produces more reliable results and does not need tuning for each individual representation task. The new texture-based segmentation algorithm is used to segment the selected organs, where only a few parameters influence the end result. Moreover, the parameters of this method are relatively easy to set, and a wide