"The written word is the most basic element of human culture. To touch the written word is to touch the essence of culture." - Xu Bing Book from the Sky certainly seemed to have fallen from the heavens: the text of this installation piece was written in a new language that resembled traditional Chinese. No matter who scours Xu Bing's book for 'meaning', they will only discover a semblance of it: mutated characters that resist interpretation. Carving out approximately four thousand wood blocks by hand, Xu Bing spent four years, from 1987 to 1991, making (in his own words) "something that said nothing". After creating a book no one could read, it only made sense for Xu Bing to develop his next project: a book that transcended barriers of language: Book from the Ground. Composed entirely of pictographs, Book from the Ground is a groundbreaking study into the concept of universal communication. Whether his goal is total comprehension or confusion, Xu Bing's masterful exploration of language challenges the way we think about the written word.

Electromagnetic imaging has been a powerful technique in various civil and military applications across medical imaging, geophysics, and space exploration. The Nyquist-Shannon theory has formed the basis for processing the signals in such systems. The advent of Compressive Sensing techniques has enabled low-dimension-model-based techniques to be used to break many of the bottlenecks of the earlier technologies. Low-dimensional-model-based electromagnetic imaging remains at its early stage, and many important issues relevant to practical applications need to be carefully investigated. In particular, this is the era of big data with booming electromagnetic sensing, by which massive data are being collected for retrieving very detailed information of probed objects. This monograph gives an overview of the low-dimensional models of structure signals, along with its relevant theories and low-complexity algorithms of signal recovery. It further reviews the recent advancements of low-dimensional-model-based electromagnetic imaging in various applied areas. It is a comprehensive introduction for researchers and engineers wishing to understand the state-of-the-art of electromagnetic imaging.