Browsing by Subject "DSLR camera"

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Access status: Open Access ,
Research on the influence of the approximated principal distance on the accuracy of orthophotoplans out of historic polychrome (on flat and quasi-flat surface)
(2012) Pastucha, Elżbieta
This artide discusses the problem of errors caused by the variability of principal distance in creating orthophotoplans of historic polychrome. Photographs used in the process of orthorectification need to have stable and known interior orientation elements, and photographs used in heritage documentation have to achieve the highest possible visual quality (including sharpness). The highest possible sharpness, provided by the variability of principal distance, and the stability of interior orientation elements are conditions which mutually exclude themselves. Analytical studies were conducted to calculate errors that would occur on resultant orthophotoplans if in the process of computing photographs (taken in autofocus mode) would take part IO elements established for average distance from the object plane. The analysis is based on the assumptions similar to the conditions found in historic sites. Three types of lenses (20 mm, 50 mm and 150 mm) were taken into consideration, two resolutions (0.3 mm and 1 mm) of final orthophotoplans. Neither the scale of adjoining photographs should be different more than ±10% nor the error caused by the variability of principal distance exceed 0.25 pixel. There were two types of objects adopted for the analysis: polychrome on the flat wall and the stone wali. Conducted studies showed a relatively small influence of approximated principal distance on geometrical accuracy (radial shifts) of resultant orthophotoplans.