What is Raster-Based Recording

Today, classroom lectures are often based on electronic materials, such as slides that have been produced with presentation software tools and complemented with digital images, video clips, and so forth. These slides are used in the live event and verbally explained by the teacher. Some lecture rooms are equipped with pen-based interfaces, such as tablet PCs, graphics tablets, or electronic whiteboards (Figure 1). These are used for freehand writing or to graphically annotate slides. Lecturers put a tremendous effort into the preparation of such electronic materials and the delivery of the respective live event. The idea of approaches for so-called automatic lecture recording is to exploit this effort for the production of educational learning material. Although it is still controversial if such documents could ever be a substitute for actual classroom teaching, it is generally agreed that they make useful, gaining complements to existing classes, and their value for education is generally accepted (Hürst, Müller, & Ottmann, 2006). While manual production of comparable multimedia data is often too costly and time consuming, such “lightweight” authoring via automatic lecture recording can be a more effective, easier, and cheaper alternative to produce high quality, up-to-date learning material. In this article, we first give a general overview of automatic lecture recording. Then, we describe the most typical approaches and identify their strengths and limitations.