— Despite the fact that sensor networks could often be deployed over three-dimensional (3D) terrains, most approaches on sensor localizations are designed and evaluated considering only two-dimensional (2D) applications. On the other hand, being the foundation of the most previous localization solutions, reliable and sufficient neighborhood-measurements are often hard to achieve for sensor nodes deployed in complex 3D terrains, which makes it difficult to extend those solutions into 3D applications. In the paper, we introduce a robust 3D localization solution called Landscape-3D, in which we treat the localization problem from a novel perspective by taking it as a functional dual of target tracking. Besides several nice features, such as high scalability, high accuracy, zero sensor-to-sensor communication overhead, low computation overhead, etc., one of the most important advantages of Landscape-3D is that it works totally independent of node densities and network topologies, which...