1. A signal processing method used with multi-aperture synthetic aperture radar data forming a sparse aperture comprising the steps of: a. collecting multiple aperture raw SAR phase history data with each collection representing an element of a sparse aperture; b. processing the raw phase history data and forming complex imagery based on the raw phase history data; c. generating x,y,z positions for individual points within the complex imagery and directly generating 3D point cloud data from the x,y,z positions; d. repeating steps (a)-(c) for multiple geometries to generate multiple 3D point cloud data sets of overlapping areas; and e. combining the multiple 3D point cloud data sets.