Methods and apparatuses for generating a frame of semantically labeled 2D data are described. A frame of sparse 3D data is generated from a frame of sparse 3D data. Semantic labels are assigned to the frame of dense 3D data, based on a set of 3D bounding boxes determined for the frame of sparse 3D data. Semantic labels are assigned to a corresponding frame of 2D data based on a mapping between the frame of sparse 3D data and the frame of 2D data. The mapping is used to map a 3D data point in the frame of dense 3D data to a mapped 2D data point in the frame of 2D data. The semantic label assigned to the 3D data point is assigned to the mapped 2D data point. The frame of semantically labeled 2D data, including the assigned semantic labels, is outputted.