Implementations described and claimed herein provide systems and methods for obstacle detection. In one implementation, a beam is transmitted at an elevation orientation from a transmit array system. The transmit array system includes transmit antenna arrays each having one or more transmit antennas. Target scatter is received at a receive array system including one or more receive channels. A virtual array is synthesized for the elevation orientation from an incidence of the target scatter on each of the one or more receive channels for each of the one or more transmit antennas. The virtual array has a size corresponding to the one or more transmit antenna arrays convolved with the receive array system. Four dimensional space information is generated from the virtual array, and any obstacles along a travel path are detected from the four dimensional space information.