Expression Method Of Small-scale Surface Of The Earth Object Based On A Large Area Of The Ellipsoid

Traditional map projection establishes corresponding functions according to certain lawsof mathematics, this solved conversion problems from the ellipsoid to plane. But deformationwill produced during the conversion, such as length (distant), angle (shape), and areadeformation. This has brought difficulties in data seamless splicing and limitations in geodeticmeasurements and drawing. Reference ellipsoid is the closest to the earth surface which canbe expressed by mathematical methods, and it is also the datum plane of geodetic calculation.So expressing surface objects on ellipsoid will be the most appropriate map manifestationswhich can avoid deformation, solve the expression problems in digital map and GISeffectively in large or worldwide area.This paper is on the basis of present preliminary studies on ellipsoid electronic maps.The earth line interpolation method is be re-chose by comparison, that is to say this researchapplies Bessel earth formula to solve the earth, concentrates the earth line by program, andlast shows the result.The main research content and results are summarized as follows:(1) On the basis of analyzing traditional map projection theory, this paper discussestraditional expression methods of surface objects with small-scale in large area.And thevarious methods discussed were compared, summed up their inadequacies and furtheremphasized the importance of the expression of surface objects based on the ellipsoid.(2)In view of the concepts and applications of digital maps which are popular online, theconcept of ellipsoid electronic maps has been further elaborated, as well as the discussion onits future application direction. (3)This paper compares the earth line interpolation methods on the base of the originalexperimental results, then proposes Bessel earth formula, concentration of the earth line, andrealizes by program. The result shows: it’s good in interpolation effect and data format, fastcalculation, and convenient to show.(4) Finally, Show the experimental data in the program, and realize the expression ofsimple surface objects on ellipsoid.The research of this paper has preliminarily realized the expression of simple surfaceobjects on ellipsoid. The program developed runs stably, the error of calculation results isSatisfying, all of this have provided the technical basis for the further research.