Height connection across sea by using satellite altimetry data sets,ellipsoidal heights,astrogeodetic deflections of the vertical,and an Earth Gravity Model

Islands and the mainland are separated by seas,and the distances between them might be so long that the height on the mainland cannot be exactly translated to the islands,resulting in different height systems on the mainland and the islands.In this study,we used astrogeodetic deflections of the vertical and ellipsoidal heights of points on the mainland and island near their coastlines to implement height connection across sea areas.First,the modeled gravity and modeled astrogeodetic vertical deflections of segmentation points along connecting routes over the sea between the mainland and the island were determined by Earth Gravity Model(EGM),and the ellipsoidal heights of segmentation points were determined by the satellite altimetry data sets.Second,we used a linear interpolation model to increase the precision of the vertical deflections of segmentation points.Third,we computed the geopotential difference of points between the mainland and the island using a method derived from geopotential theory and the astronomical leveling principle.Finally,we estimated the normal height of the point on the island using the geopotential-difference iterative computation approach.Using observed data of normal heights,ellipsoidal heights,and astrogeodetic vertical deflections referring to height sites in Qingdao,Shandong Province,we conducted a numerical experiment involving the normal height connection across sea regions.We determined the data of the ellipsoidal heights and gravity of segmentation points along the connecting route across the water in the numerical experiment using DTU10.The distance of the height connection across the sea was approximately 10.5 km.According to China's official leveling specifications,the experimental results met the criterion of third-class leveling precision.

Segmentation of Stick Text Based on Sub Connected Area Analysis

A new stick text segmentation method based on the sub connected area analysis is introduced in this paper. The foundation of this method is the sub connected area representation of text image that can represent all connected areas in an image efficiently. This method consists mainly of four steps: sub connected area classification, finding initial boundary following point, finding optimal segmentation point by boundary tracing, and text segmentation. This method is similar to boundary analysis method but is more efficient than boundary analysis.

Using image processing technology to create a novel fry counting algorithm

Quantitative counting of fry is required for multiple reasons,including breeding,transportation,and sales and creating a fish-counting algorithm using image processing technology is proposed as a useful method.The images for fish fry were preprocessed to extract the details of the target fish,using methods including binarization,dilation,and erosion.The thinning and the connected area algorithms were then independently adopted to count the fish fry within the image.The advantages and the disadvantages of the two algorithms under different densities were also compared,revealing that the fish fry pictures with a clear contrast between the foreground and background resulted in a higher accuracy.The main purpose of this research is to solve the problem of fry counting in the case of high density and high overlap.This research provides a reference point for this method based on image technology.