| 摘要 |
A system for selecting an optimal transformation T(G2;G1) between a first ellipsoid E1 (e.g., WGS 84) in a first global coordinate system G1, relative to which the survey measurements are made, and a second ellipsoid E2 in a second global coordinate system G2. A set of location coordinates (x'm,2, y'm,2,z'm,2) for M previously-surveyed locations, numbered m=1, . . . , M, and a set of location coordinates (x'n,1, y'n,1,z'n,1) for N presently-surveyed locations, numbered n=1, . . . , N (M</=N) are provided, where the first M presently-surveyed locations coincide with the M previously-surveyed locations. The transformation is chosen so that the images of the location coordinates (x'n,1,y'n,1, z'n,1) for n=1, . . . , M under T(G2;G1) are as close as possible to the corresponding location coordinates (x'm,2,y'm,2, z'm,2) for m=1, . . . , M. Given an ellipsoid and a selected survey plane tau 0 that is tangent to the ellipsoid at a selected location, a set of selected locations can be surveyed with reference to the ellipsoid, and the location coordinates of each such surveyed location can be mapped into a corresponding "survey location," defined by reference to a local coordinate system that uses the survey plane tau 0 as its base. These transformations and projections are determined and optimized in real time, while a surveyor is measuring the presently-surveyed locations in the field. The instruments used for surveying may be part of a location determination system, such as a Global Positioning System, a Global Orbiting Navigational Satellite System or Loran.
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