Robustness of Object Recognition under Extreme Occlusion in Humans and Computational Models

Most objects in the visual world are partially occluded, but humans can recognize them without difficulty. However, it remains unknown whether object recognition models like convolutional neural networks (CNNs) can handle real-world occlusion. It is also a question whether efforts to make these models robust to constant mask occlusion are effective for real-world occlusion. We test both humans and the above-mentioned computational models in a challenging task of object recognition under extreme occlusion, where target objects are heavily occluded by irrelevant real objects in real backgrounds. Our results show that human vision is very robust to extreme occlusion while CNNs are not, even with modifications to handle constant mask occlusion. This implies that the ability to handle constant mask occlusion does not entail robustness to real-world occlusion. As a comparison, we propose another computational model that utilizes object parts/subparts in a compositional manner to build robustness to occlusion. This performs significantly better than CNN-based models on our task with error patterns similar to humans. These findings suggest that testing under extreme occlusion can better reveal the robustness of visual recognition, and that the principle of composition can encourage such robustness.Comment: To be presented at the 41st Annual Meeting of the Cognitive Science Societ

Robustness of Object Recognition under Extreme Occlusionin Humans and Computational Models

Most objects in the visual world are partially occluded, buthumans can recognize them without difficulty. However, it re-mains unknown whether object recognition models like convo-lutional neural networks (CNNs) can handle real-world occlu-sion. It is also a question whether efforts to make these modelsrobust to constant mask occlusion are effective for real-worldocclusion. We test both humans and the above-mentionedcomputational models in a challenging task of object recogni-tion under extreme occlusion, where target objects are heavilyoccluded by irrelevant real objects in real backgrounds. Ourresults show that human vision is very robust to extreme oc-clusion while CNNs are not, even with modifications to han-dle constant mask occlusion. This implies that the ability tohandle constant mask occlusion does not entail robustness toreal-world occlusion. As a comparison, we propose anothercomputational model that utilizes object parts/subparts in acompositional manner to build robustness to occlusion. Thisperforms significantly better than CNN-based models on ourtask with error patterns similar to humans. These findings sug-gest that testing under extreme occlusion can better reveal therobustness of visual recognition, and that the principle of com-position can encourage such robustness

Online fringe projection profilometry based on scale-invariant feature transform

An online fringe projection profilometry (OFPP) based on scale-invariant feature transform (SIFT) is proposed. Both rotary and linear models are discussed. First, the captured images are enhanced by “retinex” theory for better contrast and an improved reprojection technique is carried out to rectify pixel size while keeping the right aspect ratio. Then the SIFT algorithm with random sample consensus algorithm is used to match feature points between frames. In this process, quick response code is innovatively adopted as a feature pattern as well as object modulation. The characteristic parameters, which include rotation angle in rotary OFPP and rectilinear displacement in linear OFPP, are calculated by a vector-based solution. Moreover, a statistical filter is applied to obtain more accurate values. The equivalent aligned fringe patterns are then extracted from each frame. The equal step algorithm, advanced iterative algorithm, and principal component analysis are eligible for phase retrieval according to whether the object moving direction accords with the fringe direction or not. The three-dimensional profile of the moving object can finally be reconstructed. Numerical simulations and experimental results verified the validity and feasibility of the proposed method.Published versio

Muscle fiber characteristics and postmortem quality of longissimus thoracis , psoas major and semitendinosus from Chinese Simmental bulls

Using Chinese Simmental cattle semitendinosus, psoas major, and longissimus thoracis samples, we assessed muscle fiber characteristics and postmortem quality. The type I, IIA, and IIB fiber diameters were greater in semitendinosus and longissimus thoracis relative to psoas major, with psoas major, semitendinosus, and longissimus thoracis having the highest respective percentages of type I, IIB, and IIA fibers. Psoas major had the highest R248 and R250 values and lowest R258 values at 1- and 6-hr postmortem. Psoas major had the lowest Warner–Bratzler shear force (WBSF), hardness, and chewiness values. The trends of WBSF, hardness, and chewiness changes decreased with increasing aging time. Semitendinosus had higher changes in WBSF than psoas major, and the number % type I fibers was correlated negatively with % changes of WBSF. Therefore, muscles with a high proportion of type IIB fibers and a low proportion of type I had lower tenderness and higher tenderization rate. Further research should be done to seek the optimal composition of muscle fiber type in order to improve beef quality, as muscle fiber type has opposite effect of tenderness background and tenderization rate

Growth variations of Dahurian larch plantations across northeast China: Understanding the effects of temperature and precipitation

Climate change is affecting the growth and distribution of trees in the Chinese boreal forest. Such changes in China, the southern terminus of the extensive Eurasian boreal forests, reflect on the changes that could occur further north under a warming climate. Most studies have found that tree growth increases with increasing temperature and precipitation in boreal forests, but there is little observational evidence of the climate thresholds that might slow these growth rates at the more extreme temperatures which are predicted to occur under future global warming. Here, we examine growth responses of this dominant boreal tree species (Larix gmelinii) to climate based on the data from plantation sample plots across a broad region (40 degrees 51'-52 degrees 58'N, 118 degrees 12' E-133 degrees 42' E) in northeast China. From statistically significant fits to quadratic equations, temperature and precipitation are the important climatic factors determining tree growth in L. gmelinii plantations at two age classes (<10 year and 10-30 year-old stands). The maximum rates of tree height and diameter at breast height (DBH) were about 0.53 m/year and 0.46 cm/year at <10 year stands, and about 0.63 m/year and 0.60 cm/year at 10-30 year stands, respectively. For stands with the highest values of mean annual increment (MAI), the corresponding optimal mean annual temperature (MAT(opt)) focused between 0.66 degrees C and 1.57 degrees C. The optimal mean annual precipitation (MAP(opt)) between 663 mm and 708 mm produced the maximal growth increments. With mean annual temperature of 2.4 degrees C and precipitation of 470 mm averaged over 1954-2005 in Chinese boreal forest region as baseline, we conservatively estimated that trees in Chinese boreal forest appear to have higher growth potentials with the maximum temperature increase of 3.6 degrees C and precipitation increase of 40%

Phase shift reflectometry for wafer inspection

In 3D measurement, specular surfaces can be reconstructed by phase shift reflectometry and the system configuration is simple. In this paper, a wafer is measured for industrial inspection to make sure the quality of the wafer by calibrating, phase unwrapping, slope calculation and integration. The profile result of the whole wafer can be reconstructed and it is a curve. As the height of the structures on the wafer is the target we are interested in, by fitting and subtracting the curve surface, the structures on the wafer can be observed on the flat surface. To confirm the quality farther, a part of the wafer is captured and zoomed in to be detected so that the difference between two structures can be observed better.Published versio

Dynamic properties of micro-NPR material and its controlling effect on surrounding rock mass with impact disturbances

A novel meta steel with negative Poisson’s ratio effect (termed as micro-NPR steel) is developed for rock support in deep underground engineering. It possesses high strength, high ductility, and high energy absorption characteristics. In this paper, static tension and modified dynamic drop hammer tests are performed on this novel material to investigate its mechanical properties first. Then based on this material, a new generation of micro-NPR anchor cable is developed and applied in field tests subjected to blasting dynamic loads. The results of laboratory tests reveal that the ultimate elongation of micro-NPR steel under dynamic impacts is more than 30% and it is over 1.5 times that of Q235; the plastic and total energy absorption of micro-NPR are both significantly higher than that of Q235. Field test indicates the fine controlling effect of micro-NPR anchor cable on surrounding rock mass under dynamic loads. Axial force confirms that micro-NPR cables can distribute and absorb the dynamic energy uniformly around the supported rock when subjected to dynamic disturbance, avoiding local failure induced by excessive stress concentration. The excavation compensation principle and energy-absorbing characteristics are used to explain the support mechanisms. Thus, micro-NPR material and anchor cable can control and prevent dynamic disasters in deep underground engineering effectively

Rockburst Hazard Control Using the Excavation Compensation Method (ECM): A Case Study in the Qinling Water Conveyance Tunnel

Rockburst disasters occur frequently during deep underground excavation, yet traditional concepts and methods can hardly meet the requirements for support under high geo-stress conditions. Consequently, rockburst control remains challenging in the engineering field. In this study, the mechanism of excavation-induced rockburst was briefly described, and it was proposed to apply the excavation compensation method (ECM) to rockburst control. Moreover, a field test was carried out on the Qinling Water Conveyance Tunnel. The following beneficial findings were obtained: Excavation leads to changes in the engineering stress state of surrounding rock and results in the generation of excess energy ΔE, which is the fundamental cause of rockburst. The ECM, which aims to offset the deep excavation effect and lower the risk of rockburst, is an active support strategy based on high pre-stress compensation. The new negative Poisson’s ratio (NPR) bolt developed has the mechanical characteristics of high strength, high toughness, and impact resistance, serving as the material basis for the ECM. The field test results reveal that the ECM and the NPR bolt succeed in controlling rockburst disasters effectively. The research results are expected to provide guidance for rockburst support in deep underground projects such as Sichuan–Xizang Railway