Retraction notice to “A novel semi-supervised method for airborne LiDAR point cloud classification” [ISPRS Journal of Photogrammetry and Remote Sensing 180 (2021) 117–129](S0924271621002100)(10.1016/j.isprsjprs.2021.08.010)

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. The authors have plagiarized parts of a paper (mainly workflow design and mathematical formulation of the various steps of the workflow) that had already appeared in the 2020 IEEE/CVF Conference on Computer Vision and Pattern Recognition, authored by Xun Xu and Gim Hee Lee, https://doi.org/10.1109/CVPR42600.2020.01372. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.