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9.3.1 Spatial resection

One of the simplest photogrammetric applications is a spatial resection from given control points, either of an aerial or a terrestrial photo.

The following input data are required:

  • Measured image coordinates of at least three control points and their ground coordinates.
  • Camera constant (and principal-point position).
  • Approximate values of the exterior orientation of the photo.

In this case the initial approximation of the photo orientation cannot be estimated by RELAX because this program computes orientation data always by means of relative orientations. However, only a rough estimation of orientation data is required. The approximate values for the projection-centre coordinates must not be more than 10-20% in error and the orientation angles not more than ±20 gon.