METRIC OR NON-METRIC CAMERAS

For a comparision of metric and non-metric cameras the reproducibility of the principal distance and the principal point are of primary interest. Such a comparison should take into account the precision requirements for these parameters. Tolerances for the parameters of the elements of inner orientation can be derived from a fictitious camera calibration. The estimations show that the computed values depend only on the opening angle of the camera and the extension of the test field, whereas the size of the camera format is immaterial. Because the tolerances are much larger for nonmal-angle cameras than for wide-angle or super-wide-angle cameras, it is suggested that, for precision measurements, cameras with long focal lengths be applied. A comparision of the computer tolerances with the reproducibility of the principal distance and the principal point indicate that non-metric cameras do fulfill the requirements within certain limits. Problems may arise under certain conditions for the principal point. An accuracy discussion also should include the parameters of exterior orientation. for example, an unfavourable base-to-height ratio or vibrations of the stereocamera might reduce the final measuring precision considerably. Under these conditions small errors of the inner orientation are of minor importance. In general, about the same measuring precision can be reached with metric and non-metric cameras. The data processing for photographs taken with non-metric cameras is practically bound to analytical methods, and sophisticated computer programs are needed. Pictures taken by metric cameras can be restituted with analog plotters. Therefore it is more a question of the restitution method than a matter of precision whether metric or non-metric cameras should be used. /Author/

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  • Supplemental Notes:
    • Presented at the 13th Congress of the International Society for Photogrammetry, Helsinki, 1976.
  • Corporate Authors:

    American Society of Photogrammetry

    105 North Virginia Avenue
    Falls Church, VA  USA  22046
  • Authors:
    • Kolbl, O R
  • Publication Date: 1976-1

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Filing Info

  • Accession Number: 00131413
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 14 1976 12:00AM