A digital camera with four flash units takes four images, each with slightly different shadow boundaries. These boundaries can then be used to compute the outlines of objects. What comes out of the camera is essentially an outline of the object, which can then be overlayed on the original photo in Photoshop. In less than a minute you have an illustration based on photo-reality. A few samples. Shown here, an engine block, the original photo of which looked murky and indistinct, now informative.
So imagine a journalist in the field covering a story s/he thinks is going to need an illustration, rather than a photo. With one of these cameras, they could shoot an illustration on the spot and file it from the field, rather than commissioning it from the pub’s art dept.