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20 pages, 6799 KiB

Open AccessArticle

Reflective Noise Filtering of Large-Scale Point Cloud Using Transformer

by Rui Gao, Mengyu Li, Seung-Jun Yang and Kyungeun Cho

Remote Sens. 2022, 14(3), 577; https://doi.org/10.3390/rs14030577 - 26 Jan 2022

Cited by 24 | Viewed by 6078

Abstract

Point clouds acquired with LiDAR are widely adopted in various fields, such as three-dimensional (3D) reconstruction, autonomous driving, and robotics. However, the high-density point cloud of large scenes captured with Lidar usually contains a large number of virtual points generated by the specular [...] Read more.

Point clouds acquired with LiDAR are widely adopted in various fields, such as three-dimensional (3D) reconstruction, autonomous driving, and robotics. However, the high-density point cloud of large scenes captured with Lidar usually contains a large number of virtual points generated by the specular reflections of reflective materials, such as glass. When applying such large-scale high-density point clouds, reflection noise may have a significant impact on 3D reconstruction and other related techniques. In this study, we propose a method that uses deep learning and multi-position sensor comparison method to remove noise due to reflections from high-density point clouds in large scenes. The proposed method converts large-scale high-density point clouds into a range image and subsequently uses a deep learning method and multi-position sensor comparison method for noise detection. This alleviates the limitation of the deep learning networks, specifically their inability to handle large-scale high-density point clouds. The experimental results show that the proposed algorithm can effectively detect and remove noise due to reflection. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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31 pages, 11596 KiB

Open AccessArticle

A Precisely One-Step Registration Methodology for Optical Imagery and LiDAR Data Using Virtual Point Primitives

by Chunjing Yao, Hongchao Ma, Wenjun Luo and Haichi Ma

Remote Sens. 2021, 13(23), 4836; https://doi.org/10.3390/rs13234836 - 28 Nov 2021

Cited by 1 | Viewed by 2077

Abstract

The registration of optical imagery and 3D Light Detection and Ranging (LiDAR) point data continues to be a challenge for various applications in photogrammetry and remote sensing. In this paper, the framework employs a new registration primitive called virtual point (VP) that can [...] Read more.

The registration of optical imagery and 3D Light Detection and Ranging (LiDAR) point data continues to be a challenge for various applications in photogrammetry and remote sensing. In this paper, the framework employs a new registration primitive called virtual point (VP) that can be generated from the linear features within a LiDAR dataset including straight lines (SL) and curved lines (CL). By using an auxiliary parameter (λ), it is easy to take advantage of the accurate and fast calculation of the one-step registration transformation model. The transformation model parameters and λs can be calculated simultaneously by applying the least square method recursively. In urban areas, there are many buildings with different shapes. Therefore, the boundaries of buildings provide a large number of SL and CL features and selecting properly linear features and transforming into VPs can reduce the errors caused by the semi-discrete random characteristics of the LiDAR points. According to the result shown in the paper, the registration precision can reach the 1~2 pixels level of the optical images. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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18 pages, 4283 KiB

Open AccessArticle

Textured Mesh Generation Using Multi-View and Multi-Source Supervision and Generative Adversarial Networks

by Mingyun Wen, Jisun Park and Kyungeun Cho

Remote Sens. 2021, 13(21), 4254; https://doi.org/10.3390/rs13214254 - 22 Oct 2021

Cited by 1 | Viewed by 2648

Abstract

This study focuses on reconstructing accurate meshes with high-resolution textures from single images. The reconstruction process involves two networks: a mesh-reconstruction network and a texture-reconstruction network. The mesh-reconstruction network estimates a deformation map, which is used to deform a template mesh to the [...] Read more.

This study focuses on reconstructing accurate meshes with high-resolution textures from single images. The reconstruction process involves two networks: a mesh-reconstruction network and a texture-reconstruction network. The mesh-reconstruction network estimates a deformation map, which is used to deform a template mesh to the shape of the target object in the input image, and a low-resolution texture. We propose reconstructing a mesh with a high-resolution texture by enhancing the low-resolution texture through use of the super-resolution method. The architecture of the texture-reconstruction network is like that of a generative adversarial network comprising a generator and a discriminator. During the training of the texture-reconstruction network, the discriminator must focus on learning high-quality texture predictions and to ignore the difference between the generated mesh and the actual mesh. To achieve this objective, we used meshes reconstructed using the mesh-reconstruction network and textures generated through inverse rendering to generate pseudo-ground-truth images. We conducted experiments using the 3D-Future dataset, and the results prove that our proposed approach can be used to generate improved three-dimensional (3D) textured meshes compared to existing methods, both quantitatively and qualitatively. Additionally, through our proposed approach, the texture of the output image is significantly improved. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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22 pages, 28554 KiB

Open AccessArticle

Reflective Noise Filtering of Large-Scale Point Cloud Using Multi-Position LiDAR Sensing Data

by Rui Gao, Jisun Park, Xiaohang Hu, Seungjun Yang and Kyungeun Cho

Remote Sens. 2021, 13(16), 3058; https://doi.org/10.3390/rs13163058 - 4 Aug 2021

Cited by 20 | Viewed by 5423

Abstract

Signals, such as point clouds captured by light detection and ranging sensors, are often affected by highly reflective objects, including specular opaque and transparent materials, such as glass, mirrors, and polished metal, which produce reflection artifacts, thereby degrading the performance of associated computer [...] Read more.

Signals, such as point clouds captured by light detection and ranging sensors, are often affected by highly reflective objects, including specular opaque and transparent materials, such as glass, mirrors, and polished metal, which produce reflection artifacts, thereby degrading the performance of associated computer vision techniques. In traditional noise filtering methods for point clouds, noise is detected by considering the distribution of the neighboring points. However, noise generated by reflected areas is quite dense and cannot be removed by considering the point distribution. Therefore, this paper proposes a noise removal method to detect dense noise points caused by reflected objects using multi-position sensing data comparison. The proposed method is divided into three steps. First, the point cloud data are converted to range images of depth and reflective intensity. Second, the reflected area is detected using a sliding window on two converted range images. Finally, noise is filtered by comparing it with the neighbor sensor data between the detected reflected areas. Experiment results demonstrate that, unlike conventional methods, the proposed method can better filter dense and large-scale noise caused by reflective objects. In future work, we will attempt to add the RGB image to improve the accuracy of noise detection. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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26 pages, 22290 KiB

Open AccessArticle

Deep Learning-Based Point Upsampling for Edge Enhancement of 3D-Scanned Data and Its Application to Transparent Visualization

by Weite Li, Kyoko Hasegawa, Liang Li, Akihiro Tsukamoto and Satoshi Tanaka

Remote Sens. 2021, 13(13), 2526; https://doi.org/10.3390/rs13132526 - 28 Jun 2021

Cited by 3 | Viewed by 3291

Abstract

Large-scale 3D-scanned point clouds enable the accurate and easy recording of complex 3D objects in the real world. The acquired point clouds often describe both the surficial and internal 3D structure of the scanned objects. The recently proposed edge-highlighted transparent visualization method is [...] Read more.

Large-scale 3D-scanned point clouds enable the accurate and easy recording of complex 3D objects in the real world. The acquired point clouds often describe both the surficial and internal 3D structure of the scanned objects. The recently proposed edge-highlighted transparent visualization method is effective for recognizing the whole 3D structure of such point clouds. This visualization utilizes the degree of opacity for highlighting edges of the 3D-scanned objects, and it realizes clear transparent viewing of the entire 3D structures. However, for 3D-scanned point clouds, the quality of any edge-highlighting visualization depends on the distribution of the extracted edge points. Insufficient density, sparseness, or partial defects in the edge points can lead to unclear edge visualization. Therefore, in this paper, we propose a deep learning-based upsampling method focusing on the edge regions of 3D-scanned point clouds to generate more edge points during the 3D-edge upsampling task. The proposed upsampling network dramatically improves the point-distributional density, uniformity, and connectivity in the edge regions. The results on synthetic and scanned edge data show that our method can improve the percentage of edge points more than 15% compared to the existing point cloud upsampling network. Our upsampling network works well for both sharp and soft edges. A combined use with a noise-eliminating filter also works well. We demonstrate the effectiveness of our upsampling network by applying it to various real 3D-scanned point clouds. We also prove that the improved edge point distribution can improve the visibility of the edge-highlighted transparent visualization of complex 3D-scanned objects. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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19 pages, 29829 KiB

Open AccessArticle

DeepLabV3-Refiner-Based Semantic Segmentation Model for Dense 3D Point Clouds

by Jeonghoon Kwak and Yunsick Sung

Remote Sens. 2021, 13(8), 1565; https://doi.org/10.3390/rs13081565 - 17 Apr 2021

Cited by 11 | Viewed by 5306

Abstract

Three-dimensional virtual environments can be configured as test environments of autonomous things, and remote sensing by 3D point clouds collected by light detection and range (LiDAR) can be used to detect virtual human objects by segmenting collected 3D point clouds in a virtual [...] Read more.

Three-dimensional virtual environments can be configured as test environments of autonomous things, and remote sensing by 3D point clouds collected by light detection and range (LiDAR) can be used to detect virtual human objects by segmenting collected 3D point clouds in a virtual environment. The use of a traditional encoder-decoder model, such as DeepLabV3, improves the quality of the low-density 3D point clouds of human objects, where the quality is determined by the measurement gap of the LiDAR lasers. However, whenever a human object with a surrounding environment in a 3D point cloud is used by the traditional encoder-decoder model, it is difficult to increase the density fitting of the human object. This paper proposes a DeepLabV3-Refiner model, which is a model that refines the fit of human objects using human objects whose density has been increased through DeepLabV3. An RGB image that has a segmented human object is defined as a dense segmented image. DeepLabV3 is used to make predictions of dense segmented images and 3D point clouds for human objects in 3D point clouds. In the Refiner model, the results of DeepLabV3 are refined to fit human objects, and a dense segmented image fit to human objects is predicted. The dense 3D point cloud is calculated using the dense segmented image provided by the DeepLabV3-Refiner model. The 3D point clouds that were analyzed by the DeepLabV3-Refiner model had a 4-fold increase in density, which was verified experimentally. The proposed method had a 0.6% increase in density accuracy compared to that of DeepLabV3, and a 2.8-fold increase in the density corresponding to the human object. The proposed method was able to provide a 3D point cloud that increased the density to fit the human object. The proposed method can be used to provide an accurate 3D virtual environment by using the improved 3D point clouds. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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19 pages, 4350 KiB

Open AccessArticle

DGCB-Net: Dynamic Graph Convolutional Broad Network for 3D Object Recognition in Point Cloud

by Yifei Tian, Long Chen, Wei Song, Yunsick Sung and Sangchul Woo

Remote Sens. 2021, 13(1), 66; https://doi.org/10.3390/rs13010066 - 26 Dec 2020

Cited by 10 | Viewed by 3895

Abstract

3D (3-Dimensional) object recognition is a hot research topic that benefits environment perception, disease diagnosis, and the mobile robot industry. Point clouds collected by range sensors are a popular data structure to represent a 3D object model. This paper proposed a 3D object [...] Read more.

3D (3-Dimensional) object recognition is a hot research topic that benefits environment perception, disease diagnosis, and the mobile robot industry. Point clouds collected by range sensors are a popular data structure to represent a 3D object model. This paper proposed a 3D object recognition method named Dynamic Graph Convolutional Broad Network (DGCB-Net) to realize feature extraction and 3D object recognition from the point cloud. DGCB-Net adopts edge convolutional layers constructed by weight-shared multiple-layer perceptrons (MLPs) to extract local features from the point cloud graph structure automatically. Features obtained from all edge convolutional layers are concatenated together to form a feature aggregation. Unlike stacking many layers in-depth, our DGCB-Net employs a broad architecture to extend point cloud feature aggregation flatly. The broad architecture is structured utilizing a flat combining architecture with multiple feature layers and enhancement layers. Both feature layers and enhancement layers concatenate together to further enrich the features’ information of the point cloud. All features work on the object recognition results thus that our DGCB-Net show better recognition performance than other 3D object recognition algorithms on ModelNet10/40 and our scanning point cloud dataset. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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15 pages, 5139 KiB

Open AccessTechnical Note

LiDAR Data Enrichment by Fusing Spatial and Temporal Adjacent Frames

by Hao Fu, Hanzhang Xue, Xiaochang Hu and Bokai Liu

Remote Sens. 2021, 13(18), 3640; https://doi.org/10.3390/rs13183640 - 12 Sep 2021

Cited by 2 | Viewed by 2751

Abstract

In autonomous driving scenarios, the point cloud generated by LiDAR is usually considered as an accurate but sparse representation. In order to enrich the LiDAR point cloud, this paper proposes a new technique that combines spatial adjacent frames and temporal adjacent frames. To [...] Read more.

In autonomous driving scenarios, the point cloud generated by LiDAR is usually considered as an accurate but sparse representation. In order to enrich the LiDAR point cloud, this paper proposes a new technique that combines spatial adjacent frames and temporal adjacent frames. To eliminate the “ghost” artifacts caused by moving objects, a moving point identification algorithm is introduced that employs the comparison between range images. Experiments are performed on the publicly available Semantic KITTI dataset. Experimental results show that the proposed method outperforms most of the previous approaches. Compared with these previous works, the proposed method is the only method that can run in real-time for online usage. Full article

(This article belongs to the Special Issue 3D Reconstruction and Visualization of Dynamic Object/Scenes Using Data Fusion)

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