A computer-implemented method for updating a 3-D map of a 3-D environment, the 3-D map comprising a plurality of voxels, wherein at least some voxels comprise a semantic class label, the 3-D map further comprising a segment database storing, for each of a plurality of segments, a segment ID, 3-D spatial information of the segment, and a semantic class label for the segment, the method comprising: obtaining the 3-D map; obtaining a 2-D image of the 3-D environment, and an associated depth map, each comprising a plurality of pixels; obtaining a pose associated with the 2-D image and the depth map; projecting the segments into the 2-D image, based on the 3-D spatial information of each segment and the pose, and associating the pixels with respective segments, to generate a class label image containing semantic class labels and a segment ID image containing segment IDs; performing geometric segmentation of the depth map, wherein the geometric segmentation is based on the segment ID image and determines an updated segment ID image; performing semantic or panoptic segmentation of the 2-D image, wherein the segmentation is based on the class label image and determines an updated semantic class label for each segment in the updated segment ID image; updating the segment IDs of one or more segments based on the updated segment ID image; updating the semantic class labels of one or more segments, based on the updated semantic class labels; and updating the semantic class labels of one or more voxels based on the updated semantic class labels. the 3-D map further comprising a segment database storing, for each of a plurality of segments, a segment ID, 3-D spatial information of the segment, and a semantic class label for the segment, the method comprising: obtaining the 3-D map; obtaining a 2-D image of the 3-D environment, and an associated depth map, each comprising a plurality of pixels; obtaining a pose associated with the 2-D image and the depth map; projecting the segments into the 2-D image, based on the 3-D spatial information of each segment and the pose, and associating the pixels with respective segments, to generate a class label image containing semantic class labels and a segment ID image containing segment IDs; performing geometric segmentation of the depth map, wherein the geometric segmentation is based on the segment ID image and determines an updated segment ID image; performing semantic or panoptic segmentation of the 2-D image, wherein the segmentation is based on the class label image and determines an updated semantic class label for each segment in the updated segment ID image; updating the segment IDs of one or more segments based on the updated segment ID image; updating the semantic class labels of one or more segments, based on the updated semantic class labels; and updating the semantic class labels of one or more voxels based on the updated semantic class labels. obtaining the 3-D map; obtaining a 2-D image of the 3-D environment, and an associated depth map, each comprising a plurality of pixels; obtaining a pose associated with the 2-D image and the depth map; projecting the segments into the 2-D image, based on the 3-D spatial information of each segment and the pose, and associating the pixels with respective segments, to generate a class label image containing semantic class labels and a segment ID image containing segment IDs; performing geometric segmentation of the depth map, wherein the geometric segmentation is based on the segment ID image and determines an updated segment ID image; performing semantic or panoptic segmentation of the 2-D image, wherein the segmentation is based on the class label image and determines an updated semantic class label for each segment in the updated segment ID image; updating the segment IDs of one or more segments based on the updated segment ID image; updating the semantic class labels of one or more segments, based on the updated semantic class labels; and updating the semantic class labels of one or more voxels based on the updated semantic class labels.