Objects In Different Positions Research Articles

One-for-all: Support-free optimized Fourier random phase for real-time multiple kinoforms generation

Existing optimized random phase (ORAP) approach mainly faces the limitations of fixed supports. Different ORAPs need to be generated for different target images with different support sizes, thus lacking flexibility and severely limiting applicability. This paper proposes a support-free optimized Fourier random phase (SF-OFRAP) approach for non-iterative kinoform generation, which greatly improves the speed and flexibility of generating kinoforms, and can achieve comparable performance to the ORAP approach. The proposed SF-OFRAP approach not only breaks the fixed support constraint of a target image, but can generate kinoforms of target images with different shapes, different positions, etc. with arbitrary supports. Our proposed SF-OFRAP approach can achieve real-time generation of kinoforms for multi-view holographic display using only a single generated SF-OFRAP without the need for additional phase compensation. The SF-OFRAP approach is suitable for real-time holographic display. Experiments verified the superiority of the produced SF-OFRAP over the ORAP method in terms of flexibility and adaptability to multiple different objects in different positions and different shapes using only one kind of these. The experimental results verify the effectiveness and excellent flexibility of SF-OFRAP for video holographic display and multi-view holographic display.

Improving Conceptual Understanding of Density and Buoyancy of Liquids through Common Knowledge Construction Model

The aim of the study was to investigate the effect of the Common Knowledge Construction Model (CKCM) on 10th-grade students’ conceptual understanding of the buoyancy and density of liquids topic. Within a pre-experimental (one group pre-test/post-test) research design, this study was conducted with 22 of 10th-grade students. To collect data, the Word Association Test (WAT) and Structural Grid (SG) were employed as pre- and post-test. Students’ conceptual understanding of the states of objects in different positions (swimming, sinking, and suspending) in the liquid was determined by means of the SG. Through the WAT, the cognitive structure of the students for the stimulus words of mass, volume, density, buoyancy, and Archimedes was determined. According to the post-tests for the SG questions, it was determined that there was a significant increase in the number of correct boxes selected and a significant decrease in the number of incorrect boxes selected. In addition, it was determined that the mind map obtained from the post-WAT, which revealed the cognitive structures of the students, had a much more interrelated and complex network. The findings obtained are compared with other related studies in the literature and some suggestions for teaching science subjects of CKCM are given.

Displaying All Object-Image Pairs of an Optical System

Ray diagrams are widely used in introductory physics textbooks to illustrate the behavior of ideal systems of lenses or mirrors in geometrical optics. Their virtue lies in their explicit display of multiple ray paths connecting object and image points, which leads naturally to an understanding of how a planar object is transformed into a planar image. This understanding is often followed by questions involving the general behavior of a lens. How do the image position and size change as the object is moved to different positions, or when the object also has significant axial depth? What image regions are visible for a particular lens aperture and eye position? Answering these questions using ray diagrams can be cumbersome, often requiring multiple diagrams with objects in different positions and leading to a fragmented understanding of lens behavior. This article illustrates how these kinds of questions can be addressed using a related visualization method I call an “image field diagram,” which trades the explicit constructions of ray diagrams for a more general display of object-image pairs.

An automatic occlusion handling method in augmented reality

PurposeTo make an augmented image realistic, the virtual objects should be correctly occluded by foreground objects. The purpose of this paper is to propose a new approach that resolves occlusion problems in augmented reality (AR). The main interest is that it can automatically obtain the proper spatial relationship between virtual and real objects in real time.Design/methodology/approachThe approach is divided into two steps: off‐line disparity map constructing and on‐line occlusion handling. In the off‐line stage, the disparity map of the real scene is constructed using the global stereo matching method prior and then the disparities are refined by means of the fast mean shift method. Since the depth values of objects in different positions are different, the real object that occludes the virtual object can be specified according to the depth value. In the on‐line stage, the contour of the specified object is tracked using the real time object tracking method with the combination of feature tracking method and minimum s‐t cut method. The augmented image with correct occlusions is produced by redrawing all the tracked object pixels on the augmented image.FindingsCompared with the existing methods, the proposed approach can automatically resolve occlusion problem in real time. The effectiveness of the method is demonstrated with several experimental results.Originality/valueThis paper makes three contributions. First, a novel framework is proposed to handle occlusion problem in AR. This framework is different to the previously proposed methods. The main procedure includes: obtain occluding real object, track the object, and redraw the pixels of the object on the composed image. It is much easier to implement and can achieve satisfactory results. Second, the disparity map is used to automatically obtain the contour of the occluding real object. To get the contour of the occluding real object precisely, the mean shift method is used to refine the disparity map. By comparing the depth value, the occluding real object can be extracted automatically. Third, the tracking method combining feature tracking method and minimum s‐t cut method ensures the real‐time requirement. The occlusion problem can be handled in real‐time.

Ecological Neural Networks for Object Recognition and Generalization

Generalization is a critical capacity for organisms. Modeling the behavior of organisms with neural networks, some type of generalizations appear to be accessible to neural networks but other types do not. In this paper we present two simulations. In the first simulation we show that while neural networks can recognize where an object is located in the retina even if they have never experienced that object in that position ('where' generalization subtask), they have difficulty in recognizing the identity of a familiar object in a new position ('what' generalization subtask). In the second simulation we explore the hypothesis that organisms find another solution to the problem of recognizing objects in different positions on their retina: they move their eyes so that objects are always seen in the same position in the retina. This strategy emerges spontaneously in ecological neural networks that are allowed to move their 'eye' in order to bring different portions of the visible world in the central portion of their retina.

Impaired Working Memory for Location but not for Colour or Shape in Visual Neglect: a Comparison of Parietal and Non-Parietal Lesions

Patients with spatial neglect due to right hemisphere pathology may show ‘revisiting’ behaviour during visual search and cancellation tasks, such that previously encountered targets are treated as if they are new discoveries. Revisiting behaviour is particularly evident when no visible trace is left to inform patients that a particular target has already been detected (Husain et al., 2001; Wojciulik et al., 2001), implying that spatial working memory may be impaired in neglect. To test whether working memory for location is selectively impaired relative to memory for colour and shape, we compared performances of right hemisphere neglect patients with parietal (n = 4) and non-parietal (n = 4) lesions on a change detection task. Patients were presented with a matrix containing four objects in different positions, and required to detect a change in the location, colour or shape of one of the objects following presentation of a brief visual mask. Parietal patients were selectively impaired in detecting location changes, regardless of the horizontal position of the object in the matrix, relative to colour and shape changes. This deficit of spatial working memory was not apparent for neglect patients with lesions that spared the parietal cortex. We conclude that the human parietal cortex is crucially involved in the updating and maintenance of spatial representations across saccades, and that neglect arising from parietal damage causes impairment in these re-mapping mechanisms.

Topographical memory impairments after unilateral lesions of the anterior thalamus and contralateral inferotemporal cortex

Monkeys with crossed unilateral excitotoxic lesions of the anterior thalamus and unilateral inferotemporal cortex ablation were severely impaired at learning two tasks which required the integration of information about the appearance of objects and their positions in space. The lesioned monkeys were also impaired at learning a spatial task and a task which required the integration of information about the appearance of objects and the background on which the objects were situated. Monkeys with only one of the unilateral lesions were not impaired and previous work has shown that monkeys with bilateral lesions of the anterior thalamus were not impaired on these tasks. These results indicate that the whole of the inferotemporal cortex-anterior thalamic circuit, which passes via the hippocampus, fornix, mamillary bodies and mamillothalamic tract, is essential for the topographical analysis of information about specific objects in different positions in space. Together with previous work, the results show that a unilateral lesion may affect cognition in the presence of other brain damage when an equivalent bilateral lesion alone does not. The tasks required the slow acquisition of information into long term memory and therefore assessed semantic knowledge although other research has shown impairment on topographical processing within working or episodic memory following lesions of the hippocampal-diencephalic circuit. It is argued that the hippocampal-diencephalic circuit does not have a role in a specific form of memory such as episodic memory but rather is involved in topographical analysis of the environment in perception and across all types of declarative memory.

Rats' processing of visual scenes: effects of lesions to fornix, anterior thalamus, mamillary nuclei or the retrohippocampal region

We analysed the effects of lesions of hippocampal-diencephalic projections — fornix (FX) mamillary bodies (MB) and anterior thalamic nuclei (AT) — and retrohippocampal (RH) lesions including entorhinal cortex and ventral subiculum, upon scene processing. All lesions except FX were neurotoxic. Rats learned to discriminate among computer-generated visual displays (“scenes”) each comprising three different shapes (“objects”). The paradigm was constant-negative; one constant scene (unrewarded) appeared on every trial together with a trial-unique variable scene (rewarded). Four types of variable scene were intermingled: (1) unfamiliar objects in different positions from those of the constant (type O+P), (2) unfamiliar objects in same positions as in the constant (type O), (3) same objects as the constant in different positions (type P), (4) same objects and positions as the constant but recombined (type X). Group RH performed like controls while groups FX, AT and MB showed (surprisingly) enhanced performance on types X and O. One explanation is that normal rats attempt to process all objects in a scene concurrently, while hippocampal-projection lesions disrupt this tendency, producing a narrower attention, which paradoxically aids performance with some variable types. The results confirm that the entorhinal cortex has a different function from other components of the hippocampal system.

Perirhinal cortex ablation in rats selectively impairs object identification in a simultaneous visual comparison task.

In Experiment 1, rats discriminated among computer-generated visual displays (scenes) comprising 3 different shapes (objects). One constant scene (unrewarded) appeared on every trial together with a trial-unique variable scene (rewarded). Four types of variable scene were intermingled: (a) unfamiliar objects in different positions from the constant; (b) unfamiliar objects in same positions as the constant; (c) same objects as the constant in different positions; (d) same objects and positions, recombined. Aspiration lesions of perirhinal cortex impaired performance with type (b) only. Experiment 2 tested spatial delayed nonmatching-to-sample. The perirhinal group were impaired nonsignificantly, and less than fornix-transected rats in an earlier study. Rats' perirhinal cortex, like monkeys', subserves object identification in the absence of memory requirement but does not contribute substantially to hippocampal system spatial memory function.