Active rough shape estimation of unknown objects

International audienceThis paper presents a method to determine the rough shape of an object. This is a step in the development of a One Click Grasping Tool, a grasping tool of everyday-life objects for an assistant robot dedicated to elderly or disabled. The goal is to determine the quadric that approximates at best the shape of an unknown object using multi-view measurements. Non-linear optimization techniques are considered to achieve this goal. Since multiple views are necessary, an active vision process is considered in order to minimize the uncertainty on the estimated parameters and determine the next best view. Finally, results that show the validity of the approach are presented

Optimizing automated characterization of liver fibrosis histological images by investigating color spaces at different resolutions

Texture analysis (TA) of histological images has recently received attention as an automated method of characterizing liver fibrosis. The colored staining methods used to identify different tissue components reveal various patterns that contribute in different ways to the digital texture of the image. A histological digital image can be represented with various color spaces. The approximation processes of pixel values that are carried out while converting between different color spaces can affect image texture and subsequently could influence the performance of TA. Conventional TA is carried out on grey scale images, which are a luminance approximation to the original RGB (Red, Green, and Blue) space. Currently, grey scale is considered sufficient for characterization of fibrosis but this may not be the case for sophisticated assessment of fibrosis or when resolution conditions vary. This paper investigates the accuracy of TA results on three color spaces, conventional grey scale, RGB, and Hue-Saturation-Intensity (HSI), at different resolutions. The results demonstrate that RGB is the most accurate in texture classification of liver images, producing better results, most notably at low resolution. Furthermore, the green channel, which is dominated by collagen fiber deposition, appears to provide most of the features for characterizing fibrosis images. The HSI space demonstrated a high percentage error for the majority of texture methods at all resolutions, suggesting that this space is insufficient for fibrosis characterization. The grey scale space produced good results at high resolution; however, errors increased as resolution decreased

Non-destructive seed detection in mandarins: comparison of automatic threshold methods FLASH and COMSPIRA MRIs

Here, we review different methods for non-destructive horticultural produce size determination, focusing on electronic technologies capable of measuring fruit volume. The usefulness of produce size estimation is justified and a comprehensive classification system of the existing electronic techniques to determine dimensional size is proposed. The different systems identified are compared in terms of their versatility, precision and throughput. There is general agreement in considering that online measurement of axes, perimeter and projected area has now been achieved. Nevertheless, rapid and accurate volume determination of irregular-shaped produce, as needed for density sorting, has only become available in the past few years. An important application of density measurement is soluble solids content (SSC) sorting. If the range of SSC in the batch is narrow and a large number of classes are desired, accurate volume determination becomes important. A good alternative for fruit three-dimensional surface reconstruction, from which volume and surface area can be computed, is the combination of height profiles from a range sensor with a two-dimensional object image boundary from a solid-state camera (brightness image) or from the range sensor itself (intensity image). However, one of the most promising technologies in this field is 3-D multispectral scanning, which combines multispectral data with 3-D surface reconstruction

Quantitative MRI study of layers and bubbles in Danish pastry during the proving process

International audienceProving of a real sized Danish pastry (10cm×5cm) was studied by MRI to visualize dough and fat layers and their evolution. The number of fat layers was varied from 4 to 12, the latter being relevant to the lower range used on an industrial scale. A new method of quantification of the three components, gas, gas-free dough and fat, in partial volume was applied to MRI images of Danish pastry during proving. The method estimated accurately the proportion of gas with a maximal bias of 5%. Sheeting steps up to 3 did not modify the inflation process of pastry and hence did not alter the gluten network and its capacity to retain gases at the global scale. A degassing effect of lamination was observed from the third sheeting step (dough layers with median thickness of about 750?m). Thickness between dough layers was not the same from the bottom to the top of the laminated dough and this was amplified during proving. However, the gas proportion in these layers was homogenous and there was no effect of the position of the layer on its expansion. Large bubbles (> 0.5mm) were visualized in dough layers but they were not elongated at this step of processing, as are bubbles typical of Danish pastry once baked. Eye-shaped bubbles were instead visualized in fat layers; their number increased more rapidly than that of fat layers. They contributed to less than 10% of overall inflation. Finally, large, undetectable portions of fat (40±13mm equivalent to about 80 pixels) were assigned to missing fat material and breaks in the layering, considered as undesirable by the bakers. These void spaces represented 7.7% of the expected total length of fat layers in the MRI images, a proportion also reported from CLSM images of the same pastries. © 2017 Elsevier Lt

Localization of teats by a 3D vision system

In order to attach automatically the teat cups on dairy cows we have designed a 3-Dimensional vision system to guide the robot arms. This system is based on the triangulation principle and consists of a CCD camera associated with two Laser plans. These components have been developed to match the accuracy required. This system has been tested on 10 cows during several weeks allowing the automatic attachment. The results strongly depend on the cows and the teats (68.5% to 91% of successful attachment rate). / Afin de poser automatiquement les gobelets trayeurs sur les vaches laitières, nous avons mis au point un système de vision 3D pour guider les bras manipulateurs. Ce système est basé sur le principe de la triangulation et consiste en l'association d'une caméra avec 2 plans laser. Ces composants ont été positionnés en fonction des vaches et des morphologies des mamelles. Une procédure de calibration a été développée pour atteindre la précision voulue. Ce système a été testé sur 10 vaches pendant plusieurs semaines permettant la pose automatique. Les résultats dépendent fortement des vaches et des trayons (de 68,5% à 91% de succès)

The size of eye-shaped bubbles in Danish pastry in relation to the size of fat fragments; a reverse engineering approach of the alveolar structure

International audienceThis study characterized the size distributions of eye-shaped bubbles as a function of different number of fat layers (NFL) (4-128) in Danish pastry. This allowed for the first time, without which it is difficult to objectively define a coarse crumb texture typical of craft products, a too fine crumb texture typical of over-lamination, or and the sizes of the bubbles typical of maximum lift. Ten to 20 mm wide bubbles did not differ in number with the NFL, except in over-laminated pastry in which their number decreased. Five-10 mm wide bubbles increased in number between 16 and 48 fat layers and explained the difference in crumb texture (more regular) and lift (+16%). One to 5 mm wide bubbles, rather round in shape, increased with the NFL, contributing to more regular crumb texture and predominated in over-laminated pastry. The number of eye-shaped bubbles was then correlated with the number of fat fragments, giving a ratio of 5 of the widths of bubbles to fat fragments. This result was logical knowing that bubbles also increase in size in the fat layers, as demonstrated earlier by MRI monitoring of Danish pastry during proving. This result also offered the opportunity of optimizing the alveolar structure of finish Danish pastry from the lamination step, using the degree of fat fragmentation at this step. The impact of these results on the usual view of bubble growth in Danish pastry is last discussed

The size of eye-shaped bubbles in Danish pastry in relation to the size of fat fragments; a reverse engineering approach of the alveolar structure

International audienceThis study characterized the size distributions of eye-shaped bubbles as a function of different number of fat layers (NFL) (4-128) in Danish pastry. This allowed for the first time, without which it is difficult to objectively define a coarse crumb texture typical of craft products, a too fine crumb texture typical of over-lamination, or and the sizes of the bubbles typical of maximum lift. Ten to 20 mm wide bubbles did not differ in number with the NFL, except in over-laminated pastry in which their number decreased. Five-10 mm wide bubbles increased in number between 16 and 48 fat layers and explained the difference in crumb texture (more regular) and lift (+16%). One to 5 mm wide bubbles, rather round in shape, increased with the NFL, contributing to more regular crumb texture and predominated in over-laminated pastry. The number of eye-shaped bubbles was then correlated with the number of fat fragments, giving a ratio of 5 of the widths of bubbles to fat fragments. This result was logical knowing that bubbles also increase in size in the fat layers, as demonstrated earlier by MRI monitoring of Danish pastry during proving. This result also offered the opportunity of optimizing the alveolar structure of finish Danish pastry from the lamination step, using the degree of fat fragmentation at this step. The impact of these results on the usual view of bubble growth in Danish pastry is last discussed