261 research outputs found
Spherical Frustum Sparse Convolution Network for LiDAR Point Cloud Semantic Segmentation
LiDAR point cloud semantic segmentation enables the robots to obtain
fine-grained semantic information of the surrounding environment. Recently,
many works project the point cloud onto the 2D image and adopt the 2D
Convolutional Neural Networks (CNNs) or vision transformer for LiDAR point
cloud semantic segmentation. However, since more than one point can be
projected onto the same 2D position but only one point can be preserved, the
previous 2D image-based segmentation methods suffer from inevitable quantized
information loss. To avoid quantized information loss, in this paper, we
propose a novel spherical frustum structure. The points projected onto the same
2D position are preserved in the spherical frustums. Moreover, we propose a
memory-efficient hash-based representation of spherical frustums. Through the
hash-based representation, we propose the Spherical Frustum sparse Convolution
(SFC) and Frustum Fast Point Sampling (F2PS) to convolve and sample the points
stored in spherical frustums respectively. Finally, we present the Spherical
Frustum sparse Convolution Network (SFCNet) to adopt 2D CNNs for LiDAR point
cloud semantic segmentation without quantized information loss. Extensive
experiments on the SemanticKITTI and nuScenes datasets demonstrate that our
SFCNet outperforms the 2D image-based semantic segmentation methods based on
conventional spherical projection. The source code will be released later.Comment: 17 pages, 10 figures, under revie
Effects of Thalidomide on the Expression of Adhesion Molecules in Rat Liver Cirrhosis
This study was to evaluate the effects of thalidomide on expression of adhesion molecules in liver cirrhosis. The cirrhosis was induced in Wistar rats by intraperitoneal injection of CCl(4), and thalidomide (10 mg/kg/day or 100 mg/kg/day) was given by intragastric administration for 8 weeks. Liver histopathology and immunohistochemistry were significantly improved and the expressions of ICAM-1, VCAM-1, E-selectin, and TNF-α mRNA and protein were decreased significantly in rats treated with a high dose of thalidomide. Close positive correlation was observed in the expression of the TNF-α mRNA and that of ICAM-1, VCAM-1, and E-selectin mRNA, respectively. These results indicate that thalidomide exerts its effect on the downregulation of adhesion molecules via TNF-α signaling pathway to inhibit liver fibrosis
SC-NeRF: Self-Correcting Neural Radiance Field with Sparse Views
In recent studies, the generalization of neural radiance fields for novel
view synthesis task has been widely explored. However, existing methods are
limited to objects and indoor scenes. In this work, we extend the
generalization task to outdoor scenes, trained only on object-level datasets.
This approach presents two challenges. Firstly, the significant distributional
shift between training and testing scenes leads to black artifacts in rendering
results. Secondly, viewpoint changes in outdoor scenes cause ghosting or
missing regions in rendered images. To address these challenges, we propose a
geometric correction module and an appearance correction module based on
multi-head attention mechanisms. We normalize rendered depth and combine it
with light direction as query in the attention mechanism. Our network
effectively corrects varying scene structures and geometric features in outdoor
scenes, generalizing well from object-level to unseen outdoor scenes.
Additionally, we use appearance correction module to correct appearance
features, preventing rendering artifacts like blank borders and ghosting due to
viewpoint changes. By combining these modules, our approach successfully
tackles the challenges of outdoor scene generalization, producing high-quality
rendering results. When evaluated on four datasets (Blender, DTU, LLFF,
Spaces), our network outperforms previous methods. Notably, compared to
MVSNeRF, our network improves average PSNR from 19.369 to 25.989, SSIM from
0.838 to 0.889, and reduces LPIPS from 0.265 to 0.224 on Spaces outdoor scenes
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