On the Texture Angle Detection Used in Space-Time Image Velocimetry (STIV)
On the Texture Angle Detection Used in Space-Time Image Velocimetry (STIV)
复制标题
时空图像测速（STIV）中的纹理角度检测
DOI：
10.1002/2017wr021913
复制
发表时间：
2017
影响因子：
5.4
通讯作者：
Ryota Tsubaki
中科院分区：
文献类型：
--
作者：
横山真;田中貴宏;杉山徹;佐土原聡;Ryota Tsubaki
时空图像测速(STIV)方法通过分析从流动水面图像序列获得的时空图像(STI)中的纹理角度来评估水面的速度。利用亮度梯度张量(BGT)来计算原始STIV中STI的纹理角度。BGT对图像质量特别是高频噪声非常敏感，这限制了速度估计的能力和精度。这项研究的目的是了解BGT对高频噪声敏感的原因以及如何解决这一缺陷。在手稿中，首先回顾了BGT的推导，然后讨论了BGT的几何表示。文中还讨论了BGT对高频噪声敏感的原因，并基于BGT的几何表示，提出了一种改进措施。为了说明这两种方法的不同之处，还使用BGT和改进的BGT分析了人工图像和现场图像的纹理角度。
The space‐time image velocimetry (STIV) method evaluates the velocity of a water surface by analyzing a texture angle within a space‐time image (STI) obtained from an image sequence of the flowing water's surface. The brightness gradient tensor (BGT) has been utilized for calculating the texture angle of the STI within the original STIV. The BGT is sensitive to image quality, especially high‐frequency noise, and this fact limits the capability and accuracy of the velocity estimation. The objectives of this study were to understand why the BGT is sensitive to high‐frequency noise and how to resolve this defect. In the manuscript, derivation of the BGT is first reviewed and then a geometric representation of the BGT is discussed. The reason the BGT is sensitive to high‐frequency noise is also discussed, and, then, based on geometric representations of the BGT, a measure to improve this defect is proposed. To demonstrate differences between the two methods, texture angles from artificial and field image sets were also analyzed using the BGT and the improved BGT.