An autonomous vehicle includes both a LIDAR sensor and a camera. A point cloud from the LIDAR sensor is processed to remove points corresponding to a ground plane and points having a reflectivity below a reflectivity threshold. The remaining points are grouped into clusters. Clusters having points satisfying a flatness threshold are then converted into 2D pixel positions in the output of the camera. Regions of interest including these 2D pixel positions are then analyzed to detect and interpret any road signs present.