A word on visuals: Redrawing a diagram
Scientist and engineers need diagrams to express ideas, and so they make it into a presentation's visual stack. Some caution is necessary when inserting diagrams into a presentation's visual stack. Some could come in the form of a scanned document, some could come from a cropped pdf, or a image file. Biology Professor Zen Faulkes has also written about the topic of redrawing here . Here is an example of a diagram that needs to be redrawn: If I would have inserted this diagram as it is there would have been several problems, including Not all text would have been legible. The diagram would have included information the audience doesn't need. The diagram might have looked pixelated. In other words, I would have lost control over it. I can recover the control by redrawing the diagram. Nowadays it is fairly easy to do this. High quality SVG maps are released under public domain or Commons Creative licenses. Plus, open source for manipulating vector graphics are n