For an autonomous flight of a UAV three components are a must 1. Lidar (e.g UTM-30LX-EW) for building 3d point cloud2. IMU/AHRS for Inertial Data3. Altimeter RADAR for monitoring altitude and collision detection These three components are required especially for complex GPS-denied or GPS challenging environments for state estimation and perception capabilities ultimately for obstacle avoidance and navigation. The Localization of the UAV in a GPS denied environment has been performed with the help of Extended Kalman Filter. Many algorithm have been invented for efficient locatization such as iterative closest point algorithm