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 structureswere 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 anapple tree (central leader trained) were measured using 6 lenses ranging in focal lengthfrom 16 to 50 mm. With a cask strained fisheye lens (FL =16 mm), the distance couldbe 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 successfulresults in the test by changing a parameter related to their perspective strengths (α).3. Three methods to correct lens distortion were devised using data of a scale-picturein a film which was photographed by the fisheye lens (FL =16 mm) ; thus, their correc-tion parameters were obtained. Outputs from the system with a subroutine program todiminish the effects of the distortion were compared among 3 methods. The results by thebest method was comparable with that from another lens but different from the other twomethods.4. Using different lens angles, photographs of densely planted apple trees a) havingvarious heights and widths, b) taken at different distances, and c) in orchards withseveral combinations of row and tree spaces were analyzed geometrically.5. Our analysis reveal that system was applicable to densely planted, dwarf apple treesusing super wide angle/ cask strained fisheye lenses.