Fruit Surface Topographic Survey Supported By a Phase Shifting Projection Moiré Technique

摘要

The pertinent literature discloses relevant research work on plant organs shape survey, considered important to all sort of crop mechanical handling, aiming mechanical bruising minimization and losses as consequences. A sequence of research work was proposed by Lino et ali, 2002 [3] starting with a topographic survey of a virtual surface (1), followed by a survey of solid symmetric figures surfaces (2), a fruit surface survey (3) and finally, the generation of a 3D digital model (4). In testing virtual surfaces, a Ronchi grid named G1 was generated in a PC, from which other grids referred as G2, G3, and G4 were set out of phase by 1/4, 1/2 and 3/4 of period from G1. However, in the present case, i.e. the step (3), grid G1 was projected onto a fruit surface instead of being virtually distorted. Projected grid was named Gd. The difference between Gd and G1 followed by filtration, generated de moiré fringes M1. The same procedure generated the fringes M2, M3 and M4 from Gd. Fringes are out of phase one from each other by 1/4 of period, which were processed by the Rising Sun Moiré software to produce packed phase and further on the unpacked fringes. Final representations in gray levels as well as in contour lines showed fruit surface topography. Images of parallel line segments projected onto the processed surface had been captured by means of the ImageJ software and the corresponding curve fitting obtained. Defective as well as bruised fruits had been tested as well. The work conclusions included commences on the reliability and usefulness of the proposed method.