Rapidform is well known in the 3D industry and provides reverse-engineering software. That means their software accepts a 3D scan and then transforms it into a usable, parametric CAD model. In practice it isn't totally magic and produce the CAD model at the touch of a button, but instead Rapidform simplifies reverse engineering by providing a huge toolkit of techniques for you to transform the scan into a true model.
The terms of the acquisition have not yet been made, but evidently 3D Systems expects this venture to add USD$15M per year to their bottom line, so you can bet they paid a large price for Rapidform.
We see this as another step in 3D Systems' initiative to simplify the route to their 3D print services. They've done this before by acquiring various software companies whose products are then integrated into the production workflow.