In this paper we introduce a new geometric calibration algorithm, and a geometric method of 3D reconstruction using a panoramic microwave radar and a camera. These two sensors are complementary, considering the robustness to environmental conditions and depth detection ability of the radar on one hand, and the high spatial resolution of a vision sensor on the other hand. This makes the approach well adapted for large scale outdoor cartography. Firstly, we address the global calibration problem which consists in finding the exact transformation between radar and camera coordinate systems. The method is based on the optimization of a non-linear criterion obtained from a set of radar-to-image target correspondences. Unlike existing methods, no special configuration of the 3D points is required, only the knowledge of inter-targets distance is needed. This makes the method flexible and easy to use by a non expert operator. Secondly, we present a 3D reconstruction method based on sensors geometry. Both methods have been validated with synthetic and real data.