In the next generations of cellular communication networks, higher density of base stations and higher frequency bands will be adopted. If being reflected by targets, the communication signal also brings information of the targets, in addition to the communication messages, to the receivers. In this paper, it is proposed to leverage the reflected communication signals to reconstruct an image of the environment. Due to the analogy to traditional synthetic aperture radar (SAR) and inverse SAR (ISAR), the principles of SAR and ISAR, namely the tomography via Fourier transformation, are adopted with necessary improvements. The algorithms are further refined to estimate the 3-dimensional silhouette of the environment. Numerical simulations are carried out to demonstrate the proposed algorithms.