Measurement of Transverse Velocity Field of NVST Solar High Resolution Image

The measurement of the transverse velocity field in the high resolution image of the Sun has been widely used in the dynamic analysis of the surface characteristics of the Chromosphere and Photosphere, however, the problem of insufficient measurement accuracy still exists. In this paper, the Demons method is introduced in detail and applied to the high resolution observation data processing of one meter vacuum solar telescope (NVST) in China. First, we select three data sets representing different bands of light and color balls at different observational intervals as test samples. When the velocity field is measured, the measurement accuracy of the velocity field is evaluated by the non-rigid registration with the image of previous time and the comparison of the structural similarity (SSIM). Experimental results show that Demons method is superior to traditional FLCT and Dave methods in the fine measurement of small scale motion, and the experimental results of sub-pixel and hyper-pixel analog displacements using Photosphere and Chromosphere image show that the point measurement accuracy can reach 0.1 pixel magnitude by our method.