A Measurement of Tree Form and Canopy Structure of Densely Planted, Dwarf Apple Trees Using Two Sides Photographs Taken at Right Angle with Wide Angle Lenses

Abstract

Application tests of a system analyzing fruit tree forms and the canopy structures were conducted for densely planted, dwarf apple trees using lenses having focal lengths (FL) shorter than 50 mm and a fisheye lens. 1. Minimum distances possible to photograph various sizes of artificial subjects and an apple tree (central leader trained) were measured using 6 lenses ranging in focal length from 16 to 50 mm. With a cask strained fisheye lens (FL = 16 mm), the distance could be reduced by one third or fourth of that in a standard lens (FL = 50 mm). 2. The photographs taken by wide angle lenses had no distortion and gave successful results in the test by changing a parameter related to their perspective strengths (alpha) 3. Three methods to correct lens distortion were devised using data of a scale-picture in a film which was photographed by the fisheye lens (FL = 16 mm); thus, their correction parameters were obtained. Outputs from the system with a subroutine program to diminish the effects of the distortion were compared among 3 methods. The results by the best method was comparable with that from another lens but different from the other two methods. 4. Using different lens angles, photographs of densely planted apple trees a) having various heights and widths, b) taken at different distances, and c) in orchards with several combinations of row and tree spaces were analyzed geometrically. 5. Our analysis reveal that system was applicable to densely planted, dwarf apple trees using super wide angle/ cask strained fisheye lenses.