Lianlei Shan

Dr. Lianlei Shan


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
12 January 2021 in IEEE Geoscience and Remote Sensing Letters
Verified
Journal Article
Closed access
LSLianlei Shan
Lianlei Shan
WWWeiqiang Wang
Weiqiang Wang
Recently, fully convolutional network (FCN)-based (Long et al. , 2015) networks have made impressive success in semantic segmentation, and these approaches achieve satisfactory results in natural images. However, in the field of high-resolution remote sensing image segmentation, the accuracy has a considerable huge gap compared with that of natural images. Through the development process of semantic segmentation, we found that the key to accurate segmentation is the context. Effective networks can always obtain large contexts, which means that context is the key to one successful segmentation network. For high-resolution remote sensing images, their elements always extend to large scope and they have no clear or regular boundaries. As a result, it needs more context to correctly classify each pixel. However, the networks designed for natural images obviously do not meet this requirement, and thus, they achieve poor segmentation results for high-resolution images. Therefore, we do some targeted improvements. Based on one powerful backbone, we add two new fusions called unit fusion and cross-level fusion, respectively. Unit fusion makes the connection from the encoder part to the decoder part not only occur in the final output of each dense block but also in the middle feature layers inside one dense block. These added fusions make feature fusion in the same level more complete, which is of great significance for complex and zigzag boundary areas. As a complement for unit fusion, cross-level fusion aims to enhance the fusion of different dense blocks. Specifically, cross-level fusion learns from the internal structure of the dense block and applies the design to the whole network level. It can incorporate nonadjacent features and rapidly increase the receptive field and context, which is very effective for the segmentation of targets with very large sizes. Experiments on Deepglobe (Demir et al. , 2018) show significant improvements in our work.

13 December 2021 in IEEE Transactions on Geoscience and Remote Sensing
Verified
Journal Article
Closed access
LSLianlei Shan
Lianlei Shan
WWWeiqiang Wang
Weiqiang Wang
KLKe Lv
Ke Lv
BLBin Luo
Bin Luo
Incremental learning using neural networks achieves great success in semantic segmentation but still suffers from catastrophic forgetting. In this article, we propose an effective class-incremental segmentation method without storing old data. To alleviate the issue of forgetting, we present two important modules, i.e., the deep feature distillation (DFD) module and the label mixed (LM) module. The DFD module is established to learn a good feature representation of old classes by distilling a new compact feature representation from different layers of networks. The proposed LM module first identifies the examples (pixels) of old classes with high confidences utilizing the output of old models, and then, they are combined with examples of new classes to supervise the training of new models, which can achieve a good balance between learning new classing and avoiding forgetting old ones. Our ablation studies show that the DFD module and the LM module can make the learning network obtain 6.2% and 15% performance gains [mean Intersection over Union (mIOU)], respectively. Furthermore, by introducing the supervision of output distillation loss, we compare our method with several state-of-the-art methods in the extensive experiments, and the experimental results all show that our method is significantly superior to them on the dataset of aerial images.

21 December 2022 in IEEE Transactions on Geoscience and Remote Sensing
Verified
Journal Article
Closed access
LSLianlei Shan
Lianlei Shan
WWWeiqiang Wang
Weiqiang Wang
KLKe Lv
Ke Lv
BLBin Luo
Bin Luo
Deep neural networks achieve significant progress in semantic segmentation but still suffer from the catastrophic forgetting problem, i.e., networks will forget old classes as they learn new ones. In this article, we propose an effective class-incremental segmentation framework without storing old data. Specifically, to alleviate the issue of catastrophic forgetting, we present two important modules, i.e., the Pixel-level Feature Generation (PFG) module, and the Task-wise Knowledge distillation (TKD) module. The PFG module is designed to constantly generate any number of features of the old classes to keep the old memory. The PFG module is the first attempt to use the generative method in class-incremental segmentation of aerial images, and it abandons the previous image generation approach but to generate pixel-level features, which is more suitable for the segmentation task. Meanwhile, the proposed TKD module is specially designed for class incremental tasks, and it only compares classes in the same learning step (task), thus avoiding the squeezing of new classes to old classes when the output is normalized (softmax), making distillation more effective. Sufficient experiments show that our method is remarkably effective and achieves more than 4.5% gains compared with state-of-the-art methods, and more than 13% compared with baselines, on all learning conditions. The ablation studies show that the PFG module and the TKD module are both indispensables. Besides, the proposed framework can be well combined with any existing class incremental learning method to achieve better performance.

30 November 2023 in IEEE Transactions on Circuits and Systems for Video Technology
Verified
Journal Article
Open access
WWWeijia Wu
Weijia Wu
YZYuzhong Zhao
Yuzhong Zhao
ZLZhuang Li
Zhuang Li
LSLianlei Shan
Lianlei Shan
HZHong Zhou
Hong Zhou
MSMike Zheng Shou
Mike Zheng Shou
Image segmentation based on continual learning exhibits a critical drop of performance, mainly due to catastrophic forgetting and background shift, as they are required to incorporate new classes continually. In this paper, we propose a simple, yet effective Continual Image Segmentation method with incremental Dynamic Query (CISDQ), which decouples the representation learning of both old and new knowledge with lightweight query embedding. CISDQ mainly includes three contributions: 1) We define dynamic queries with adaptive background class to exploit past knowledge and learn future classes naturally. 2) CISDQ proposes a class/instance-aware Query Guided Knowledge Distillation strategy to overcome catastrophic forgetting by capturing the inter-class diversity and intra-class identity. 3) Apart from semantic segmentation, CISDQ introduce the continual learning for instance segmentation in which instance-wise labeling and supervision are considered. Extensive experiments on three datasets for two tasks ( i.e . continual semantic and instance segmentation are conducted to demonstrate that CISDQ achieves the state-of-the-art performance, specifically, obtaining 4.4% and 2.9% mIoU improvements for the ADE 100-10 (6 steps) setting and ADE 100-5 (11 steps) setting.

21 March 2025 in Remote Sensing
Verified
Journal Article
Open access
PDF file
WMWeijun Meng
Weijun Meng
LSLianlei Shan
Lianlei Shan
SMSugang Ma
Sugang Ma
DLDan Liu
Dan Liu
BHBIN HU
BIN HU
With advancements in remote sensing technologies, high-resolution imagery has become increasingly accessible, supporting applications in urban planning, environmental monitoring, and precision agriculture. However, semantic segmentation of such imagery remains challenging due to complex spatial structures, fine-grained details, and land cover variations. Existing methods often struggle with ineffective feature representation, suboptimal fusion of global and local information, and high computational costs, limiting segmentation accuracy and efficiency. To address these challenges, we propose the dual-level network (DLNet), an enhanced framework incorporating self-attention and cross-attention mechanisms for improved multi-scale feature extraction and fusion. The self-attention module captures long-range dependencies to enhance contextual understanding, while the cross-attention module facilitates bidirectional interaction between global and local features, improving spatial coherence and segmentation quality. Additionally, DLNet optimizes computational efficiency by balancing feature refinement and memory consumption, making it suitable for large-scale remote sensing applications. Extensive experiments on benchmark datasets, including DeepGlobe and Inria Aerial, demonstrate that DLNet achieves state-of-the-art segmentation accuracy while maintaining computational efficiency. On the DeepGlobe dataset, DLNet achieves a 76.9% mean intersection over union (mIoU), outperforming existing models such as GLNet (71.6%) and EHSNet (76.3%), while requiring lower memory (1443 MB) and maintaining a competitive inference speed of 518.3 ms per image. On the Inria Aerial dataset, DLNet attains an mIoU of 73.6%, surpassing GLNet (71.2%) while reducing computational cost and achieving an inference speed of 119.4 ms per image. These results highlight DLNet’s effectiveness in achieving precise and efficient segmentation in high-resolution remote sensing imagery.

5 February 2025 in Remote Sensing
Verified
Journal Article
Open access
PDF file
BDBingyun Du
Bingyun Du
LSLianlei Shan
Lianlei Shan
XSXiaoyu Shao
Xiaoyu Shao
DZDongyou Zhang
Dongyou Zhang
WWWang xinrui Xinrui Wang
Wang xinrui Xinrui Wang
JWJiaxi Wu
Jiaxi Wu
With the advancement of remote sensing technology, the acquisition of ultra-high-resolution remote sensing imagery has become a reality, opening up new possibilities for detailed research and applications of Earth’s surface. These ultra-high-resolution images, with spatial resolutions at the meter or sub-meter level and pixel counts exceeding 4 million, contain rich geometric and attribute details of surface objects. Their use significantly improves the accuracy of surface feature analysis. However, this also increases the computational resource demands of deep learning-driven semantic segmentation tasks. Therefore, we propose the Transform Dual-Branch Attention Net (TDBAN), which effectively integrates global and local information through a dual-branch design, enhancing image segmentation performance and reducing memory consumption. TDBAN leverages a cross-collaborative module (CCM) based on the Transform mechanism and a data-related learnable fusion module (DRLF) to achieve adaptive content processing. Experimental results show that TDBAN achieves mean intersection over union (mIoU) of 73.6% and 72.7% on DeepGlobe and Inria Aerial datasets, respectively, and surpasses existing models in memory efficiency, highlighting its superiority in handling ultra-high-resolution remote sensing images. This study not only advances the development of ultra-high-resolution remote sensing image segmentation technology, but also lays a solid foundation for further research in this field.