1. An image generating device comprising: an image former comprising a computer-readable media storing code executable by a computer processor of a computing system, the computing system coupled to a radar that is operable to transmit and receive electro-magnetic radiation at a plurality of frequencies in the range of 500 Mega-Hertz to 3 Giga-Hertz, the image former operable, at each of the plurality of frequencies, to: receive, from the radar, the electro-magnetic radiation reflected from a building; generate an image of the building from the received electro-magnetic radiation; adjust the image according to a material characteristic of a wall of the building, the material characteristic comprising a thickness of the wall and a dielectric constant of a material in which the wall is made; apply a phase gradient factor to a plurality of contiguous regions of the image, the plurality of the contiguous regions overlapping one another, the phase gradient factor comprising a phase difference of the received electro-magnetic radiation between adjacent samples of each of the plurality of contiguous regions; and combine the image with other images received from the radar at the differing plurality of frequencies to form a resulting image.