Stereo Perception Research Articles

YOLOv7-3D: A Monocular 3D Traffic Object Detection Method from a Roadside Perspective

Current autonomous driving systems predominantly focus on 3D object perception from the vehicle’s perspective. However, the single-camera 3D object detection algorithm in the roadside monitoring scenario provides stereo perception of traffic objects, offering more accurate collection and analysis of traffic information to ensure reliable support for urban traffic safety. In this paper, we propose the YOLOv7-3D algorithm specifically designed for single-camera 3D object detection from a roadside viewpoint. Our approach utilizes various information, including 2D bounding boxes, projected corner keypoints, and offset vectors relative to the center of the 2D bounding boxes, to enhance the accuracy of 3D object bounding box detection. Additionally, we introduce a 5-layer feature pyramid network (FPN) structure and a multi-scale spatial attention mechanism to improve feature saliency for objects of different scales, thereby enhancing the detection accuracy of the network. Experimental results demonstrate that our YOLOv7-3D network achieved significantly higher detection accuracy on the Rope3D dataset while reducing computational complexity by 60%.

Improved stereo perception in coronary angiography using the X-ray tube as the viewpoint and validation with 3D printed models

Coronary angiography (CAG) provides two-dimensional images, but a clinician who is experienced in percutaneous coronary interventions can use information from these images to interpret spatial depth and infer the three-dimensional (3D) locations of vessels. We hypothesized that CAG results were equivalent to the mirror image of a coronary artery perspective projection, and a stereo perception could be easily established when the viewpoint of the angiogram was the X-ray tube instead of the detector. To eliminate the influence of heartbeat and respiration, a 3D-printed a coronary artery model was constructed for analysis. The effects of gantry movements during digital subtraction angiography (DSA) on the image were used to identify factors that affected DSA image transformation. Then, based on these factors, DSA imaging was simulated using UG NX software with three methods: (i) a perspective projection with the detector as the viewpoint; (ii) a parallel projection; and (iii) a mirror image of the perspective projection with the X-ray tube as the viewpoint. Finally, the resulting 3D images were compared with the DSA image. Our mirror image of the coronary artery perspective projection that used the X-ray tube as the viewpoint fused precisely with the CAG results and provided exact simulations of all the effects of DSA gantry movements on the DSA image. CAG results were equivalent to the mirror image of coronary artery perspective projection, and the stereo perception was easily established using the X-ray tube as the viewpoint.

Stereo Perception Optimization of Line-of-Sight and Non-Line-of-Sight Sensor Networks

Stereo Perception Optimization of Line-of-Sight and Non-Line-of-Sight Sensor Networks

Convex Vision-Based Negative Obstacle Detection Framework for Autonomous Vehicles

This study investigates the convex optimization frameworks for accurate and fast negative obstacle detection as well as depth estimations that are vital for real-time, superior autonomous vehicle operations. A convex framework is proposed in conjunction with a unique stereo perception approach to manage the complex nature of such invisible obstacles. The proposed stereo configuration incorporates an alignment that displaces the cameras along a vertical baseline to extract useful information pertaining to negative obstacle features for various illustrative terrain settings. The convex framework exploits these properties to evaluate depth jumps in the disparity space image and perform geometrical analysis of potential occlusion regions. The corresponding convex formulations are based on linear matrix inequalities to detect sudden disparity, angle profile, and intensity variations for potential negative obstacles and to estimate the internal depth of the detected obstacles. Experimental results demonstrate that consecutive processes can be structured in a convex framework to efficiently identify negative obstacle attributes at a range of distances for texture varying environments, providing a vital extension to real-time vehicular system implementations with superior detection rates.

Stereopsis and Eye Movement Abnormalities in Parkinson's Disease and Their Clinical Implications.

BackgroundParkinson’s disease (PD) is not exclusively a motor disorder. Among non-motor features, patients with PD possess sensory visual dysfunctions. Depth perception and oculomotor deficits can significantly impact patients’ motor performance. Stereopsis and eye behavioral study using 3D stimuli may help determine their implications in disease status.ObjectiveThe objective of this study is to investigate stereopsis and eye movement abnormalities in PD with reliable tools and their correlation with indicators of PD severity. We hypothesize that patients with PD exhibit different eye behaviors and that these differences may correlate to the severity of motor symptoms and cognitive status.MethodsControl and PD participants were first evaluated for visual acuity, visual field, contrast acuity, and stereo perception with 2D and Titmus stereotests, followed by the assessment with a 3D active shutter system. Eye movement behaviors were assessed by a Tobii X2-60 eye tracker.ResultsScreening visual tests did not reveal any differences between the PD and control groups. With the 3D active shutter system, the PD group demonstrated significantly worse stereopsis. The preserved cognitive function was correlated to a more intact stereo function. Patients with PD had longer visual response times, with a higher number of fixations and bigger saccade amplitude, suggesting fixation stabilization difficulties. Such changes showed a positive correlation with the severity of motor symptoms and a negative correlation with normal cognitive status.ConclusionWe assessed stereopsis with a 3D active shutter system and oculomotor behaviors with the Tobii eye tracker. Patients with PD exhibit poorer stereopsis and impaired oculomotor behaviors during response time. These deficits were correlated with PD motor and cognitive status. The visual parameters may potentially serve as the clinical biomarkers for PD.

Intelligence-Endogenous Networks: Innovative Network Paradigm for 6G

Feature applications envisioned in the 6G era, represented by holographic communication, full-sensing communication, intelligent transportation, and intelligent manufacturing in terms of virtual and physical integration, immersion, contextualization, and personalization, have placed high demands on the intelligentization of 6G networks. The current network operating mechanism based on rule-based algorithms is limited by rigid preset rules. It is difficult to adapt dynamically to constantly changing user needs and network environments. In order to enable the network to effectively accumulate and independently utilize the operating experience and realize the independent iterative evolution of network operation, management, and control capabilities, this article proposes the concept of the intelligence-endogenous network (IEN). The IEN aims to introduce knowledge graph and artificial intelligence technologies into networks to characterize, construct, learn, and apply the network's multidimensional subjective and objective knowledge. Based on the learned knowledge, an IEN can realize stereo perception, decision deduction, and dynamic adjustment, so the network can change as it needs for whatever new services we want. The article introduces the basic concepts, goals, and meanings of the IEN, together with its key principles and technologies, and illustrates how it innovatively responds to the current network's multifaceted challenges with an intuitive use case.

3DFP-FCGAN: Face completion generative adversarial network with 3D facial prior

Face completion is a domain-specific image inpainting problem. Most existing face completion methods fail to synthesize fine-grained facial structures due to the undifferentiated treatment of face images and other scene images. To handle this problem, we propose an end-to-end deep generative model based approach which makes full use of the facial prior knowledge, including 2D facial geometry priors from facial parsing maps and landmarks, as well as the 3D depth prior. We adopt a coarse-to-fine inpainting framework where the 2D facial geometry priors based on coarse faces are extracted to guide the refinement network for better planar facial textures and structures. Moreover, a novel 3D regularized reconstruction loss is proposed for the enhancement of the stereo perception of generated faces. Experimental results on two large-scale benchmarks CelebA and CelebA-HQ show that our method significantly outperforms the state-of-the-arts in generating more visually realistic and pleasing faces. Code is available at .

Results of Using Alternating Presentation of Stereostimuli in Children with Functional Scotoma in Non-Paralytic Strabismus

The work is devoted to one of the actual problems of modern strabismology — the study of the ability to stereo perception in children with non-paralytic strabismus.Purpose: to study the capability to stereovision with alternating presentation of stereostimuli in children with functional scotoma in non-paralytic strabismus.Patients and methods. 113 children with functional scotoma (FS) in non-paralytic strabismus were observed. We used stereostimuli with different characteristics in the following regimes of presentation: 1) the regime of simple monocular alternating (alternate presentation of an image for the right eye and the left eye); 2) the regime having an “empty” interval (black background) between monocular phases; 3) the regime having a binocular phase (a binocular image containing details corresponding to the stimuli for the right eye and the left eye) between monocular phases.Results. It was found that in 23 (20,3 %) children, the ability to stereo perception was completely absent. All these children had stable total FS (monocular vision). In the remaining 90 children (with unstable or regional FS), the ability to stereo perception was shown with some stimuli in some modes of their alternating presentation. For stimuli with a central arrangement of linear parts, the stereo effect was possible when they were presented in an alternating mode with an “empty” interval lasting from 20 to 70 ms in combination with the duration of monocular phases from 30 to 90 ms. For stimuli with a peripheral arrangement of linear elements, 22.1 % of children were able to stereo perception not only in the “empty” interval mode, but also in the simple alternation mode. At the same time, the greatest number of children capable of stereo perception was detected when using the mode with an “empty” interval of 30–60 ms and a duration of monocular phases of 40–60 ms. With random-dot stimuli, none of the children in this group were capable of stereo perception.Conclusion. Our results suggest that even in patients with FS in non-paralytic strabismus, stereo perception is possible under the conditions of alternating presentation of stimuli with certain characteristics. In this case, the most likely appearance of a stereo effect with stimuli containing peripheral linear elements that create a stereo effect when presented in an alternating mode with an empty interval between monocular phases.

Recovering depth from stereo-input without using any oculomotor information: A computation model

Human beings can perceive depth by using binocular disparity, namely the difference between a stereo-pair of retinal images. It is commonly believed that the visual system requires oculomotor information about the relative orientation between the two eyes to perceive depth on the basis of binocular disparity. Such oculomotor information can be obtained from the efference copy of the oculomotor signal, or it can be derived from the vertical component of the binocular disparity (vertical disparity). Psychophysical studies have shown that stereo depth perception is affected by both the efference copy and by the vertical disparity. But note that any role for the efference signal for spatial perception is limited and the process using vertical disparity is slow. These effects are too restricted to explain depth perception under natural viewing conditions in which natural eye movements are made. In the present study, I describe a computational model that can recover depth from a stereo-pair of retinal images based only on the geometrical optics. This model treats depth recovery as a Direct problem rather than as an Inverse problem because it does not need to make use of any oculomotor information or of any a priori constraints. In this model, oculomotor information is not even implicitly recovered. Simply put, this paper shows that, at least from a computational perspective, oculomotor information and a priori constraints are not actually required for the stereo perception of depth. Having such a model allows us to discuss psychophysical and neurophysiological phenomena, as well as their mechanisms, without assuming that the human visual system needs oculomotor information to recover depth in a 3D scene from stereo retinal images.

Full-Color See-Through Three-Dimensional Display Method Based on Volume Holography.

We propose a full-color see-through three-dimensional (3D) display method based on volume holography. This method is based on real object interference, avoiding the device limitation of spatial light modulator (SLM). The volume holography has a slim and compact structure, which realizes 3D display through one single layer of photopolymer. We analyzed the recording mechanism of volume holographic gratings, diffraction characteristics, and influencing factors of refractive index modulation through Kogelnik’s coupled-wave theory and the monomer diffusion model of photopolymer. We built a multiplexing full-color reflective volume holographic recording optical system and conducted simultaneous exposure experiment. Under the illumination of white light, full-color 3D image can be reconstructed. Experimental results show that the average diffraction efficiency is about 53%, and the grating fringe pitch is less than 0.3 μm. The reconstructed image of volume holography has high diffraction efficiency, high resolution, strong stereo perception, and large observing angle, which provides a technical reference for augmented reality.

Восприятие виртуальных стереообъектов: особенности взаимодействия зрительных механизмов и пространственные перцептивные эффекты

The purpose of our study was investigation of the peculiarities of human visual perception in virtual environment created on the basis of stereo technologies. The participants were 100 adults aged from 17 to 79 years (40 males and 60 females, average age 32,9 years). Observation of virtual stereo objects was provided by computer software “Fusion” created for measuring visual fusion reserves which characterize the quality of binocular mechanisms of stereo perception. Test stimuli were random dot stereograms (RDSs) encoding a square test object moving from the screen to the observer. Separate presentation of the stimuli to the left and right eyes was based on the opposite circular polarization method. The participant’s task was to observe virtual stereo objects and describe perceived vi- sual images: their sizes, positions in depth and directions of movement. It has been found that, in conditions of view- ing the same virtual stereo objects, the participants with normally functioning mechanisms of binocular stereopsis could perceive quite different stereo images. On the basis of the perceived stereo image parameters, all participants were divided into four types. The described phenomena and the identified typology of spatial perceptual stereo effects could be considered as the consequences of restructuring interaction of visual sensory, accommodative and oculo-motor mechanisms involved in visible image formation when adapting to a virtual environment.

Vehicle Detection: A Review

Vehicle detection based computer vision is the essential algorithm in autonomous driving, aims at identifying which locating vehicles by digital images or videos. The basic idea of vehicle detection is detecting “blocks,” which reflects the position of the vehicle in images or videos. Besides, this paper discusses 3D vehicle detection algorithms based on stereo perception, which originated from advanced planar vehicle detection perception. Finally, this paper summarizes the vehicle detection algorithms in recent years in terms of the difference between the feature extraction approach and the perceived results. It proposes hypotheses for further in-depth study of the vehicle detection algorithms.

Three-dimensional light-field display with enhanced horizontal viewing angle by introducing a new lenticular lens array

Three-dimensional (3D) light-field display simulates the authentic light-field distribution of objects, but its narrow viewing angle remains an obstacle for medical and educational applications. Here, a light-field display system based on lenticular lens array (LLA), lens array (LA) and holographic functional screen (HFS) is demonstrated, which can regenerate the high viewpoint density 3D light-field with both large horizontal viewing angle and appropriate vertical viewing angle. The LLA is introduced in the system to expand crucial horizontal viewing angle and to improve stereo perception. The application of optical optimization lens and HFS can suppress aberration and improve the accuracy of reconstructed light-field distribution. In the experiment, a full-parallax 3D light-field display prototype with the correct geometric occlusion is realized with 70 degrees horizontal viewing angle and 30 degrees vertical viewing angle, where 11000 viewpoints are obtained. A sophisticated 3D scene is optically reconstructed with the synchronization of capture and image encoding, which proves the feasibility and applicability of the method.

The perception of the stereo effect in bilateral and bimodal cochlear implant users and its contribution to music enjoyment.

ObjectivesIn this clinical study, stereo perception of music samples and its contribution to music enjoyment in CI users is investigated. It is studied in free field as well as direct audio presentation.Methods20 bilateral and 9 bimodal CI users performed stereo detection tests and music enjoyment ratings. Music was presented either in mono or in stereo in free field or with direct audio presentation. Stereo detection was assessed with a 3-AFC paradigm. Music enjoyment was studied with scale ratings.ResultsFor bilateral CI users, stereo detection increased from 52% correct in free field to 86% with direct audio presentation. Increased music enjoyment with improved stereo detection was obtained. Bimodal CI users could not identify stereo sounds. Music enjoyment did not increase for stereo presentations in bimodal subjects.DiscussionFor bilateral CI users, improved stereo detection might increase music enjoyment with direct audio presentation, which is likely due to bypassing the room acoustics. In bimodal CI users, no clear improvement was found, which is likely attributed due to the different hearing losses and therefore individually different interaural frequency overlaps between the hearing aid and the cochlear implant.ConclusionDirect audio presentation is an efficient method to improve music enjoyment in bilateral CI users.

Monitoring Technology of Power System Operation State Based on Stereo Sensing

In recent years, the development of computer technology, automation control technology and communication technology has provided new hardware and software support for the implementation of distribution network operation monitoring. In the daily production of the oil field, the reliability and stability of the power supply are the key links to ensure the completion of the production tasks of the oil field. This paper studies the problem of scene depth reconstruction in panoramic technology. On this basis, the panoramic depth map is combined with the panoramic image, and the three-dimensional panoramic characteristics are reconstructed from the visual and environmental aspects of the stereo perception model suitable for its performance. This paper develops an oilfield distribution network operation monitoring system based on stereo perception, and develops corresponding system management software. This paper first determines the mathematical model of the distribution network line loss calculation, and introduces the principle of GPRS technology to formulate a specific network plan for distribution network operation monitoring. Finally, based on the terminal data collection method of CDD-IDT / GPRS, the development of terminal system management software is finally completed. Field test results show that the stereoscopic perception-based oil field distribution network operation monitoring system developed in this paper has high accuracy of accident prediction, strong real-time performance, stable and reliable operation, and the average transmission time of each data in the stereoscopic perception based monitoring network transmission It is 1.88 seconds, which can be displayed immediately after pre-loading.

Multi-camera visual SLAM for off-road navigation

With the rapid development of computer vision, vision-based simultaneous localization and mapping (vSLAM) plays an increasingly important role in the field of unmanned driving. However, traditional SLAM methods based on a monocular camera only perform well in simple indoor environments or urban environments with obvious structural features. In off-road environments, the situation that SLAM encounters could be complicated by problems such as direct sunlight, leaf occlusion, rough roads, sensor failure, sparsity of stably trackable texture. Traditional methods are highly susceptible to these factors, which lead to compromised stability and reliability. To counter such problems, we propose a panoramic vision SLAM method based on multi-camera collaboration, aiming at utilizing the characters of panoramic vision and stereo perception to improve the localization precision in off-road environments. At the same time, the independence and information sharing of each camera in multi-camera system can improve its ability to resist bumps, illumination, occlusion and sparse texture in an off-road environment, and enable our method to recover the metric scale. These characters ensure unmanned ground vehicles (UGVs) to locate and navigate safely and reliably in complex off-road environments.

Результаты использования альтернирующего предъявления различных стереостимулов для исследования способности к стереовосприятию у детей с послеоперационной остаточной микродевиацией

Purpose. To study abilities to stereo-perception in children with postoperative residual micro-deviation via alternating presentation of different stereo stimuli. Material and methods. The study included 30 children aged 8 to 16 years (average 12.5 years) with operated strabismus who have postoperative residual micro-deviation (mean 6.8±0.4 pr.D) at the time of the observation. Residual esotropia was observed in 21 children (5 of them had also a vertical micro-deviation), exotropia – 9 children. Along with the usual ophthalmic examination and evaluation of stereovision by means of classical Lang-test and Fly-test we used our own stereo-tests developed on the basis of stereo images created by J. Ninio. Our stereo-tests included stimuli: 1) with a central location of vertical or horizontal stripes with a successful fusion and an ability to stereo perception of tilt relative to the horizontal axis (vertical strip) or turn around the vertical axis (horizontal strip); 2) with a peripheral location of vertical or horizontal stripes creating respectively the effect of tilt or reversal turn; 3) randomly-point stereo-grams, creating the impression of a successful fusion of vertical or horizont al cylinder. The subject observed the images shown on the monitor screen from a distance of 50 cm from the eyes through the red-blue light filters in conditions of full prismatic compensation of the angle of strabismus and optimal spectacle or contact correction of ametropia. The stimuli were presented both in the static version and in the modes of alternation via a computer pr ogram developed by M. V. Zhmurov. Three modes of alternative presentation of stimuli were used: 1) the mode with a consecutive monocular presentation of visual stimuli corresponding to the right and left eyes 2) the mode with the presence of an empty interval between monocular phases; 3) the mode with the presence of a binocular phase between monocular phases. Results. In all patients, the results of the study of stereovision with Lang-test, Fly-test and static version of our stereo-tests used in this work were negative. In eight children of the general group, the stereo effect appears only with stereo-images with a peripheral arrangement of vertical or horizontal stripes in all three modes of the alternating presentation. In 22 children, the stereo effect appears with stimuli both with peripheral and with the central location of the stripes in all three modes of their alternating presentation. The volume effect with random-dot stereo-stimuli occurred in only nine children, with a stable bifoveal fusion, and only in the mode of alternating presentation with an empty interval between monocular phases. Thus, in this mode of alternating presentation it was possible to perceive not only linear, but also random-dot stereo-images. Comparing the maximum durations of monocular phases for different images in this mode, a significant difference was found between the mean values for stimuli with peripheral vertical stripes (57±2.3 ms) and with central vertical stripes (43.2±2.6 ms; p<0.001), as well as between the mean values for stimuli with peripheral horizontal stripes (56±2.1 ms) and central horizontal stripes (43.6±3.4 ms; p<0.002). The maximum duration of monocular phases for random-dot stereo-images producing the effect of a vertical cylinder (32.2±5.8 ms) and a horizontal cylinder (31.1±6.7 ms) was significantly lower than the maximum duration for stimuli with peripheral vertical and horizontal stripes (p<0.001). The same regularities were observed for the maximum dur ation of the empty i nterval. Conclusion. The stereo-perception is possible in children with residual postoperative micro-deviation. At the same time, the most effective of the images we used are stimuli with a peripheral arrangement of elements that create a stereo effect in condition of a successful fusion. The mode of alternating presentation of stimuli with the presence of an empty interval between monocular phases creates more favorable conditions for the appearance of a stereo effect in comparison with the mode of alternating presentation of stimuli with the presence of a binocular phase between monocular phases and in comparison with the mode of alternating monocular phases. Stereovision with random-dot stereograms causes serious difficulties in most children with postoperative microdeviation, however, it is possible in some cases in the mode of alternating presentation of stimuli with the presence of an empty i nterval between monocular phases.

Результаты использования альтернирующего предъявления стимулов в ортоптическом лечении у детей

Purpose. To evaluate the results in the use of different modes for alternating presentation of stimuli in the orthoptic treatment of strabismus in children. Material and methods. The study included 41 patients with a nonparalytic strabismus (30 children with esotropy and 11 children with exotropy) aged from 7 to 16 years. For additional studies of binocular functions, we used a modified Bagolini test and our own stereo-test created for the conditions of anaglyph separation of visual fields. During the first examination the results with all the used stereo-tests (the Flytest, the Lang-test, and the stereo image that we created) were negative. Besides to the static presentation of test images, three different modes of alternating presentation of stimuli were used: 1) with consecutive monocular presentation of visual stimuli corresponding to the right and left eye; 2) with the presence of an empty interval between monocular phases; 3) with the presence of a binocular phase between monocular phases. The duration of the monocular and binocular phases, as well as the empty interval, was regulated by the researcher. Depending on the results of the examination, an optimal mode of alternative presentation of stimuli for the orthoptic tr eatment was selected individually. Results. In the duration of the monocular phase 50 ms in combination with the duration of an empty interval 50 ms, the majority of children (32 of 41) with strabismus were able to have stereovision. As a result of orthoptic exercises, the number of patients capable of bifoveal fusion increased from 24.4% to 48.8%. Stereovision appeared in 39% of children according to the Fly-test and in some cases according to the Lang-test. In all children with moderate amblyopia the visual acuity increased on average from 0.23±0.01 to 0.52±0.05 (p<0.001), in children with mild amblyopia the visual acuity increased on average from 0.66±0.02 to 0.93±0.01 (p<0.001). A reduction of the strabismus angle or an elimination of postsurgical microdeviation occur in one-third of children. Conclusion. The proposed method for the study of binocular functions in patients with strabismus allows to evaluate the ability to the bifoveal fusion and stereo perception not only with static presentation of visual stimuli, but also with the use of different modes of their alternating presentation. The most favorable mode for the elimination of functional inhibition is the mode of alternating presentation of stimuli with the presence of an empty interval not less than 50 ms between the monocular phases, which are also not less than 50 ms. This mode with the combination of monocular phase duration and empty interval duration in the range from 30 to 60 ms creates the most favorable conditions for the appearance of the stereo effect in the majority of the patients. The use of optimal individually chosen regime of alternating presentation of the stimuli allows to improve significantly the binocular functions, to increase the visual acuity, and in some cases to reduce the angle of strabismus or to eliminate postsurgical microdeviations.

Third dimension of a map

Abstract. A communication of information from its producer to a user can be done in many ways which differs in their effectivity. Although a map is a native communication channel for presenting of spatial data, a presentation of spatial data in 3D environment is a growing alternative in recent years. Therefore this chapter describes basic principles of dealing with third dimension in a map.Note that this contribution focuses on matters related purely to GIS. The contribution is not going to describe advanced 3D scene visualization techniques such as shadow modelling, ray-tracing, etc. (as they belong to computer graphics).Also a type of display in not addressed in detail. Just to mention in general, having a 3D scene, it can be displayed on:Monitor – then it is perspective visualization. A perception of depth emerges by moving the virtual observer position or line of sight.Monitor using passive or active glasses / 3D monitor – a full stereo perception emerges.3D print / hologram – physical/virtual three-dimensional scene emerges.Coming to GIS related issues. First of all, there exists solutions displaying 2.5 dimensional data and they are commonly called 3D GIS as well even if they do not support full 3D objects.Next, there are two different types of coordinate systems used: a Cartesian coordinate system, speaking geographically – a projected coordinate system, e.g. an UTM Zone. Then all coordinates are in the same units (usually meters). More challenging is the other type – a geographic coordinate system using latitude and longitude locating both objects and phenomena on Earth globe, but metric units for (ellipsoidal or orthometric) height – then different types of units (angular and metrical) are used for different axes. Such a situation is typical for virtual globes.Talking about cartography, there are two main approaches to visualize a 3D scene, photorealistic versus symbolized). Photorealistic approach tends to use real world textures and create an impression as close to real world as possible. The other approach, consisting of applying a cartographic symbols on the scene, challenges contemporary cartography, as not all cartographic techniques can be transferred from 2D to 3D. There can be distinguished among techniques able to apply without a change, techniques need to be adapted and inapplicable techniques.And last but not least major issue is that 3D GIS has to deal with large data in a different way than in 2D. Two dimensional GIS deals with large amount of data by a concept of scale dependent rendering (also called a scale dependent map) and using pyramiding and generalization techniques. But important thing is that always the whole thematic layer (or even a map) is represented at one level of detail in one view. When zoom in or out, an appropriate level of pyramid is depicted. A different approach is needed in 3D – instead of using one zoom level as a threshold for what and how to visualize, the observer position and line of sight have to be taken into account. Then, objects closer to observer have to be presented in more detailed way than objects away, no matter if they are from the same layer or different layers.

The EEG Activity during Binocular Depth Perception of 2D Images.

The central brain functions underlying a stereoscopic vision were a subject of numerous studies investigating the cortical activity during binocular perception of depth. However, the stereo vision is less explored as a function promoting the cognitive processes of the brain. In this work, we investigated a cortical activity during the cognitive task consisting of binocular viewing of a false image which is observed when the eyes are refocused out of the random-dot stereogram plane (3D phenomenon). The power of cortical activity before and after the onset of the false image perception was assessed using the scull EEG recording. We found that during stereo perception of the false image the power of alpha-band activity decreased in the left parietal area and bilaterally in frontal areas of the cortex, while activity in beta-1, beta-2, and delta frequency bands remained to be unchanged. We assume that this suppression of alpha rhythm is presumably associated with increased attention necessary for refocusing the eyes at the plane of the false image.