| 摘要 |
A survey of an airport runway or other large structure includes statistical correction of error caused by atmospheric turbulence. Visible grid markers are placed, e.g., at twenty foot centers, in rows and columns on the runway. Absolute vertical reference points are established, favorably by using floats in tubes joined to a common trough pipe, for each row of the grid markers. A holographic reference grid is reconstructed, preferably at a safe distance from the runway, so that the reconstructed reference grid is disposed in the vertical plane of a particular row of grid markers. Then the locations of the grid markers, the absolute reference points, and the reference grid are recorded a plurality of times, for example, by multiple-exposing photographic film. The statistical mean locations of the images of the grid markers and absolute reference points are determined, relative to the reconstructed reference grid.
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