The Research And Application Of Image Measurement Method For River Rigime Width And Surface Flow Field In Yellow River Model

This paper was supported by the Education Ministry and province cooperation project"Yellow River Modelnetwork image monitoring and processing system".With the development of the computer technology and image technology, the method based on image analysis and related technical has been successfully used in realizing the flow field non-contact measure ment of the river model. There are a lot of ways to measure the River regime and the Surface velocityof the Yellow river model. But most methods can not achieve totally automatic multi-point measurement。In this paper, based on the study of the river model experiment,we proposed a series of measurement methods of the surface flow of the Yellow River Method for the regime extraction and the measurement of widthd and surface velocity.This paper described the measurement methods of the the river regime width and the testing principle and method of surface flow field in detail around the image measurement technology in the application of river model experiment. During river regime management and the width measurement, according to the characteristics of the flow field and the measurement purpose and the comparison of a variety of edge detection operator, we puts forward a set of new edge extraction method, the method uses the adaptive threshold Canny edge detection algorithm and the morphological connected domain segmentation method to extract the edges, then use the pixel calculation method, we can real-time access to the precise width of the river regime through the proportion of conversion.In the processing of surface velocity measurement, Selected rivers in the model the spread of the tracer particle surface. Throw selected tracer particles on the surface of the river model, then we capture flow images through the camera and pass the image data into the computer. After the image pre-preprocessing, we use the PIV technique to automaticly measure the surface velocity.During the Processing , in order to get better results to reduce errors, we proposed an improved selection method of adaptive analysis window and the of cross-correlation calculation based on Hartley transform, instead of the traditional fixed window and Fourier transform method, to measurethe the surface velocity and obtain velocity information. After above, paper has a talk about the filtering and interpolation of the vector results, to improve the velocity measurement accuracy.In this paper, the software of system was compiled by matlab 7.0, including the imge preprocessing, river flow measurements and surface velocity measurements. We take the application experiment respectively in the model test bench and entity Yellow River model, and successfully measured out the width of the regime and surface velocity. Paper also has analyzed the sources of the results and errors, and discussed the shortage and development of the image measurement technology application in the measurment of river model.