Measurement of volume of macaw palm fruit using traditional and the digital Moiré techniques

Abstract

A B S T R A C TThe macaw palm crop has been studied because of its bioenergy potential due to the high oil yield, which is linked to fruit maturity stage. Digital images have been adopted as a contactless way to obtain information about fruit surface area and volume, acting as a sensor for quality control and the classification of fruits, based on physical aspects during the maturation stage. The aim of this study was to estimate the volume of macaw palm fruits from digital models obtained by the Moiré technique using only one camera, associated with digital imageprocessing tools to unwarp the images, allowing the comparison with conventional methods. The volumes obtained by the Moiré technique were compared with those obtained by water displacement method (WDM) and millet-seed displacement method (SDM). The results show that the volumes measured by the Moiré technique exhibited a mean error of 13.54% compared with the SDM, and 11.09% when compared to WDM, which indicates that the digital Moiré technique is a robust, low-cost tool to measure the volume of macaw palm fruits.Mensuração do volume do fruto de macaúba por meio das técnicas convencionais e pela técnica digital de Moiré R E S U M OA cultura da macaúba vem sendo estudada devido ao seu potencial bioenergético propiciado pela alta produtividade de óleo que, por sua vez, está associado ao estádio de maturação do fruto. Imagens digitais têm sido utilizadas como forma para extrair informações sem contato sobre a área superficial e volume de frutos, com a finalidade de construir sensores que possam atuar no controle de qualidade e classificação a partir de aspectos físicos ligados ao estádio de maturação. O objetivo deste trabalho foi estimar o volume do fruto de macaúba a partir de imagens digitais obtidas pela técnica de Moiré por meio de uma única câmera associada ao uso de técnicas de correção digital da deformação das imagens, comparando os volumes estimados por métodos convencionais. Os volumes obtidos pela técnica de Moiré foram comparados com os volumes obtidos pelo método de deslocamento de coluna de água e pelo método do deslocamento de sementes de painço. Os volumes medidos pela técnica de Moiré apresentam um erro médio de 13,54 e de 11,09% quando comparados aos métodos convencionais, sendo considerada uma alternativa robusta e de baixo custo para a mensuração do volume de frutos de macaúba.

The Efficiency of the Moiré Technique for Three-Dimensional Measures of Grape Bunches

“…Costa et al [13] used the Moiré technique to estimate the volume of macaw palm fruit and compared the Moiré technique to the displacement method of a fluid in order to obtain the volume of the fruit. Lino and Fabbro [14] applied the Moiré technique to obtain the topography of artificial fruit made of paraffin on a 1:1 scale.…”

“…The authors obtained a digital model of pears through the Moiré technique and compared it to the three-dimensional model obtained through a laser scanner. In both cases [13,14], the authors found a good correlation between the three-dimensional model obtained through the Moiré technique and the comparison methods, which were volume displacement of a fluid [13] and the 3D model obtained through a laser scanner [14].…”

Phenological behavior and agronomic potential of blackberry and hybrids in a subtropical region

“…The longitudinal and transverse diameter of the fruits were measured with the aid of a stainless steel digital caliper (brand Stainless Hardened). The volume was estimated by the water displacement method, by initially immersing five blackberry fruits in a graduated cylinder containing 100 mL of water and recording the difference between volume before and after fruit immersion (Costa et al, 2016). The fruits of each block were harvested for the determination of yield and estimated productivity of the fruits, being weighed using a semi-analytical digital scale (model N0 4052E, brand LUXOR).…”

Applying Linear Regression to Estimate Weight of Non Axi-Symmetric fruit

“…Many researches in estimation of fruits' weight using 2D images used Regression as learning method to estimate fruits' weight from its pre-determined volume. It has shown good accuracy in estimating weight of apple, sweet-lime, lemon and orange [7] with R 2 > 0.86 and macaw palm fruits [8] with R 2 of 0.837. Other research estimated weight of apples using Linear Regression based on its diameter and area and show accuracy of 96.5% [9].…”