  With the objective of exploiting hardware capabilities and preparing the
ground for the next-generation X-band synthetic aperture radar (SAR) missions,
TerraSAR-X and TanDEM-X are now able to operate in staring spotlight mode,
which is characterized by an increased azimuth resolution of approximately 0.24
m compared to 1.1 m of the conventional sliding spotlight mode. In this paper,
we demonstrate for the first time its potential for SAR tomography. To this
end, we tailored our interferometric and tomographic processors for the
distinctive features of the staring spotlight mode, which will be analyzed
accordingly. By means of its higher spatial resolution, the staring spotlight
mode will not only lead to a denser point cloud, but also to more accurate
height estimates due to the higher signal-to-clutter ratio. As a result of a
first comparison between sliding and staring spotlight TomoSAR, the following
were observed: 1) the density of the staring spotlight point cloud is
approximately 5.1--5.5 times as high; 2) the relative height accuracy of the
staring spotlight point cloud is approximately 1.7 times as high.
