基于光学成像技术的泥沙颗粒级配及形态测定方法研究

Determination of sediment particle size, morphology, roundness and grading is foundtion to study the movement of sediment and riverbed evolution. The normal methods of Sediment grain size analysis has sieving, sedimentation， resistance and Laser particle size method, above methods can only obtain grain size and gradation can not directly obtain morphological information, which effect the depth of understanding and basic theoretical research on sediment motion. Based on optical imaging technology, the project will develop a new method of lensless optical imaging and measurement system, which can abtain size, roundness, grading and shape information, and solve problem of measuring range is narrow, slow processing speed, morphological information single issues such as conventional image analysis. The project will focus on sediment particle dispersion technology, optical imaging device and image processing technology,and establish the mathematical relations of sediment particle size, the light resistance characteristic, light intensity, gray value and other parameters,to restructure sediment particle informtion.Through dynamic monitoring projection information of sediment particles in different time, and obtain maximum, intermediate and minimum particle size,relize to measure particle shape coefficient. Based on the fractal theory, study on characteristics of sediment particle size distribution and shape,to establish calculation method of shape dimension fractal dimension, and provide a new method of describing quantitatively the characteristics of sediment particles. The research results are expected to develop the theory of sediment particle analysis, and solve the problem of size analysis and morphological measurement of wide grading, irregular shape of sediment particle, and get more sediment characteristic information, which will provide technical support to sediment-disciplinary.

泥沙颗粒粒径、形态、圆度和级配等参量测定是研究泥沙运动和河床演变规律的基础。常用颗粒分析方法有筛分法、沉降法、电阻法和激光粒度法，上述方法只能获取粒径和级配，不能同时直接获取形态信息，影响了对泥沙运动规律的认识和基础理论研究深度。本项目拟基于光学成像技术，研发一种新型、无透镜的泥沙颗粒分析方法，解决常规图像分析法中测量范围窄、处理速度慢、形态信息单一等问题。拟重点研究利用泥沙颗粒分散技术、光学成像装置和图像处理技术，获取泥沙颗粒在平行光源照射下的投影信息，构建泥沙颗粒大小、阻光特性、光强、图像灰度值等参量间的数学关系，通过实时动态监测泥沙颗粒不同时刻截面投影，获取最大、中间和最小粒径，实现泥沙颗粒形状系数的准确测量；并基于分形理论，建立泥沙颗粒形状分形维数计算方法，实现泥沙颗粒形态的定量描述。成果有望发展泥沙颗粒分析理论，解决宽级配、不规则形状泥沙颗粒测量问题，为泥沙学科研究提供技术保障。

对比分析了常规泥沙颗粒测试技术，构建了泥沙颗粒图像分析系统，深入研究了图像格式、材质对泥沙图像的影响，建立了行搜索法提取泥沙颗粒图像，经等效变换获取泥沙颗粒粒径、级配等信息，并采用颗粒表面分形维数分析了泥沙颗粒表面粗糙度。主要研究内容及成果如下：.1）对比总结了常规泥沙颗粒分析技术优缺点. 采用筛分法、沉降法、电阻法和激光粒度法测量了均匀沙和非均匀沙的粒径及级配，对于形状规则的泥沙颗粒，激光粒度法测试结果重复性更好、相对误差更小。.2）构建了泥沙颗粒图像采集装置. 构建了泥沙颗粒图像采集装置，中间设置隔层安装摄像机。LED光强可根据泥沙颗粒粒径调节，解决了固定光强情况下小颗粒泥沙被散射光淹没等问题。.3）研究了图像格式、材质对泥沙颗粒图像的影响，分析了RGB行灰度分布特征. 8位灰度图像处理单色沙效果较好，直方图呈双峰形态，易于阈值分割，而对于多色沙测量误差较大；RGB图像对单色沙和多色沙处理效果均较好，测试结果重复性优于8位灰度图像。RGB行灰度值在泥沙颗粒边缘处开始下降，至泥沙颗粒中心处，灰度值降至最低，随着向颗粒边缘发展，灰度值逐渐增大。 .4）建立了泥沙颗粒图像行搜索法和空心图像填充法 . 逐行对比分析各象素RGB灰度值，基于行灰度分布特征提取泥沙颗粒图像。行搜索法提取的泥沙颗粒图像存在空心、缺失等现象，运用连通域，实现空心填充。.5）开发了具有自主知识产权的泥沙颗粒图像分析系统. 基于VB编程语言，开发了泥沙颗粒图像分析系统，具有图像采集、RGB直方图、 图像滤波、行灰度特征分析、颗粒提取、粒径计算、级配统计、数据对比和多样本数据融合等功能。.6）运用分形分维方法分析了泥沙颗粒表面粗糙度. 基于周长-面积法分析了泥沙颗粒表面分形维数，结果表明维数可用于泥沙颗粒表面粗糙度的描述。