Line drawing techniques are important methods to illustrate shapes. Existing feature line methods, e.g., suggestive contours, apparent ridges, or photic extremum lines, solely determine salient regions and illustrate them with separate lines. Hatching methods convey the shape by drawing a wealth of lines on the whole surface. Both approaches are often not sufficient for a faithful visualization of organic surface models, e.g., in biology or medicine. In this paper, we present a novel object-space line drawing algorithm that conveys the shape of such surface models in real-time. Our approach employs contour-and feature-based illustrative streamlines to convey surface shape (ConFIS). For every triangle, precise streamlines are calculated on the surface with a given curvature vector field. Salient regions are detected by determining maxima and minima of a scalar field. Compared with existing feature lines and hatching methods, ConFIS uses the advantages of both categories in an effective and flexible manner. We demonstrate this with different anatomical and artificial surface models. In addition, we conducted a qualitative evaluation of our technique to compare our results with exemplary feature line and hatching methods.

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Abstract. Real-time functional MRI (rfMRI) offers new experimental paradigms, such as biofeedback and interactive experiments. Usually, several separated software systems are used to control the MRI measuring sequence, the stimulus presentation, and the statistical analysis, which leads to problems concerning the user communication and synchronisation and interaction of the different software systems. Here, an approach is developed which helps to overcome those difficulties by utilising a uniform parameter management using a flexible parameter description that can be used simultaneously by different separated software systems. This approach is used to control two modules: a realtime fMRI application which extracts the current activation, and an analysis-system which evaluates the current brain activation to influence the stimulus presentation and provide feedback to the volunteer.