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Weighted Point Cloud Augmentation for Neural Network Training Data Class-imbalance

Griffiths, D; Boehm, J; (2019) Weighted Point Cloud Augmentation for Neural Network Training Data Class-imbalance. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences , XLII-2 (W13) pp. 981-987. 10.5194/isprs-archives-XLII-2-W13-981-201. Green open access

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Abstract

Recent developments in the field of deep learning for 3D data have demonstrated promising potential for end-to-end learning directly from point clouds. However, many real-world point clouds contain a large class im-balance due to the natural class im-balance observed in nature. For example, a 3D scan of an urban environment will consist mostly of road and façade, whereas other objects such as poles will be under-represented. In this paper we address this issue by employing a weighted augmentation to increase classes that contain fewer points. By mitigating the class im-balance present in the data we demonstrate that a standard PointNet++ deep neural network can achieve higher performance at inference on validation data. This was observed as an increase of F1 score of 19% and 25% on two test benchmark datasets; ScanNet and Semantic3D respectively where no class im-balance pre-processing had been performed. Our networks performed better on both highly-represented and under-represented classes, which indicates that the network is learning more robust and meaningful features when the loss function is not overly exposed to only a few classes.

Type: Article
Title: Weighted Point Cloud Augmentation for Neural Network Training Data Class-imbalance
Open access status: An open access version is available from UCL Discovery
DOI: 10.5194/isprs-archives-XLII-2-W13-981-201
Publisher version: https://www.int-arch-photogramm-remote-sens-spatia...
Language: English
Additional information: © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/).
Keywords: point cloud, classification, deep learning, augmentation, dataset
UCL classification: UCL
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UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10075646
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