eess.IV - 2023-10-29

Subjective Quality Evaluation of Point Clouds Using a Head Mounted Display

paper_url: http://arxiv.org/abs/2310.19179
repo_url: None
paper_authors: Joao Prazeres, Rafael Rodrigues, Manuela Pereira, Antonio M. G. Pinheiro
for: 这个论文报告了对静止点云编码器MPEG V-PCC、G-PCC、深度学习编码器RS-DLPCC以及受欢迎的Draco编码器的主观质量评估。
methods: 该论文使用了18名参与者通过头戴式显示器直接比较了3D表示的扭曲点云的视觉效果，并对所获得的主观评分（MOS）与之前两项研究中对同一内容的视觉效果进行了比较，包括潘森相关指数、斯宾塞排名相关指数、平均方差和外围异常指数。
results: 结果表明这三项研究之间存在高度相关性，并且对所有评估中的差异没有发现任何显著差异。

Abstract
This paper reports on a subjective quality evaluation of static point clouds encoded with the MPEG codecs V-PCC and G-PCC, the deep learning-based codec RS-DLPCC, and the popular Draco codec. 18 subjects visualized 3D representations of distorted point clouds using a Head Mounted Display, which allowed for a direct comparison with their reference. The Mean Opinion Scores (MOS) obtained in this subjective evaluation were compared with the MOS from two previous studies, where the same content was visualized either on a 2D display or a 3D stereoscopic display, through the Pearson Correlation, Spearman Rank Order Correlation, Root Mean Square Error, and the Outlier Ratio. The results indicate that the three studies are highly correlated with one another. Moreover, a statistical analysis between all evaluations showed no significant differences between them.

摘要
(Simplified Chinese)这篇论文报道了一项主观质量评估，涉及到静止点云编码器MPEG codecs V-PCC和G-PCC、深度学习基于的RS-DLPCC编码器以及受欢迎的Draco编码器。18名参与者通过头戴式显示器 visualized 3D表示distorted点云，可以直接与参考进行比较。获得的主观意见分（MOS）在这个主观评估中被与之前两个研究相比较，这两个研究分别使用2D显示器和3D立体显示器显示同一内容。通过皮尔逊相关度、Spearman排序相关度、平均方差误差和异常比率进行比较。结果表明这三个研究之间存在高度相关性，并且在所有评估中没有发现显著差异。

Transport-of-Intensity Model for Single-Mask X-ray Differential Phase Contrast Imaging

paper_url: http://arxiv.org/abs/2310.19087
repo_url: None
paper_authors: Jingcheng Yuan, Mini Das
for: 该研究旨在提高软组织和肿瘤的可见度，使用X射线阶段差图像技术。
methods: 该研究提出了一种基于运输Intensity公式的单面phas imaging系统模型，以提供图像形成过程的直观理解。此外，该研究还展示了使用单一的干扰图像来 Retrieval attenuation和分别阶段差信息，不需要spectral信息或探测器/Mask移动。
results: 该研究通过实验和Monte Carlo仿真示出了模型的有效性和提议的Retrieval方法。该模型超越了现有模型的限制，提供了直观的图像形成过程的视觉化，同时允许优化分别阶段差投影 geometries，进一步提高了实际应用的可行性。

Abstract
X-ray phase contrast imaging has emerged as a promising technique for enhancing contrast and visibility of light-element materials, including soft tissues and tumors. In this paper, we propose a novel model for a single-mask phase imaging system based on the transport-of-intensity equation. Our model offers an intuitive understanding of signal and contrast formation in single-mask phase imaging systems. We also demonstrate efficient retrieval of attenuation and differential phase contrast with just one intensity image without requiring spectral information or mask/detector movement. The model validity as well as the proposed retrieval method is demonstrated via both experimental results on a system developed in-house as well as with Monte Carlo simulations. Our proposed model overcomes the limitations of existing models by providing an intuitive visualization of the image formation process. It also allows optimizing differential phase imaging geometries for practical applications, further enhancing broader applicability. Furthermore, the general methodology described herein offers insight on deriving transport-of-intensity models for novel X-ray imaging systems with periodic structures in the beam path.

摘要