The Analysis Of Abnormal Elevation Points In Aerial Topographic Map Data Update

Topographic map update occupies the important status in the national census.It can makes country more understanding of the geographical distribution and provide much help for the country's in the late planning?design?management?reconstruction and restoration work.During 1:10000 the topographic map update of Dong ting lake area by photogrammetry,when we automatically check the data through procedure,we found that elevation points using stereo pairs to collection by the workers much belong to the point of height anomaly.So we use the measured elevation points by RTK instead of the points of height anomaly in flat area,and take the method of modified contour to deal with the points of height anomaly in hilly area or mountain during the actual project.I had selected 30 sheets to conduct a test on the mountains,hilly area,the flat area in my thesis and each terrain chooses 10 sheets.I use the measured discrete points to construct TIN,to make DEM,then utilize the method of linear interpolation to interpolate the elevation values.As a result,the same point has two elevation values.Calculating the difference of two elevation values and Mid-height Error of each sheet,analyzing data,statistics data of Mid-height Error and difference of two elevation values through the method of probability and statistic,this steps can complete my experiment and get useful data.Firstly,I get a conclusion that the elevation of points meet the accuracy requirement in hills,mountain areas,but can't demand the requirement of the accuracy in flat areas.In order to get higher precision of elevation point data,I put forward some ways to improve the precision of the elevation points,such as in large area using unmanned aerial vehicle low-flying,local area using the field actual measurement,the combination of the unmanned aerial vehicle with RTK.It can provide a reference for the topographic map update in the future,improve the work efficiency and get more effective data.