The impact of night vision goggles on way-finding performance and the acquisition of spatial knowledge

OBJECTIVE: This study examined the effects of night vision goggles (NVGs) on navigation and way-finding performance and the acquisition of spatial knowledge. BACKGROUND: Although numerous studies have examined the effects of NVGs on visual perception, few have examined the effects of using NVGs on the acquisition and expression of spatial cognition. METHOD: Participants learned the environment through active navigation and way finding, searching for targets within a life-sized maze with or without NVGs. Knowledge of the environment was then tested with two spatial memory tests. RESULTS: Findings show that navigation and way finding with NVGs appear to be harder, as indicated by longer navigation times and additional, unnecessary turns, than they are without NVGs. Moreover, change in navigation performance over the course of the way-finding trials varied as a function of group assignment indicating that NVGs influenced the learning process. NVG users demonstrated a significant decrease in navigation times earlier as well as significant decreases in navigational legs compared with the control group. In judging the positions of objects relative to target objects in different rooms in the maze, performance was better for participants without NVGs than for those with NVGs. In a map-drawing task, participants in the NVG group were more likely to position objects incorrectly and to receive worse scores than the controls. CONCLUSION: These results demonstrate that NVGs affected not only spatial navigation and way-finding performance but also the acquisition of spatial knowledge. APPLICATION: These degradations in spatial knowledge should be considered in operational planning and NVG training programs.     

The apparent and effective dimensionality of representations of objects

Information displays commonly use 2-D and 3-D objects even though the numbers represented are 1-D. This practice may be problematic because the psychophysical relation between perceived and physical magnitudes is generally nonlinear for areas and volumes. Nonetheless, this research shows that apparent 2-D and 3-D objects can produce linear psychophysical functions if only one dimension shows variation. Processing time increases with the number of dimensions in the objects that show variation, not with the apparent dimensionality. Indeed, when only one dimension showed variation, apparent 3-D objects were judged more quickly than were apparent 2-D or 1-D objects. These results present a challenge for computational models of size perception and have implications for the design of information displays. Actual or potential applications of this research include the design and use of statistical graphs and information displays; objects that display variation in more than one dimension should not be used to represent single (1-D) numerical variables if they are to be judged accurately and rapidly.     

A mechanism of automatic 3D object modeling

The symbolic representation of 3D objects is the fundamental knowledge for computer systems to understand the environment. This knowledge is usually assumed to exist in a computer but can also be acquired by accumulating spatial features extracted from sensory inputs at different viewing directions. This paper first investigates surface visibility and, then, after introducing mass vector chains (MVC), discusses the relationship between MVC and the spatial closure of object models. An automatic modeling mechanism is established with the observation that the boundary of an object is closed only if the MVC of its model is closed or, alternatively, the tail-to-head vector of an unclosed MVC estimates the visible direction of the missing surfaces. Experimental results and an algorithm are also given at the end     

Adaptive 3-D object recognition from multiple views

The authors address the problem of generating representations of 3-D objects automatically from exploratory view sequences of unoccluded objects. In building the models, processed frames of a video sequence are clustered into view categories called aspects, which represent characteristic views of an object invariant to its apparent position, size, 2-D orientation, and limited foreshortening deformation. The aspects as well as the aspect transitions of a view sequence are used to build (and refine) the 3-D object representations online in the form of aspect-transition matrices. Recognition emerges as the hypothesis that has accumulated the maximum evidence at each moment. The `winning' object continues to refine its representation until either the camera is redirected or another hypothesis accumulates greater evidence. This work concentrates on 3-D appearance modeling and succeeds under favorable viewing conditions by using simplified processes to segment objects from the scene and derive the spatial agreement of object features     

Signature file as a spatial filter for iconic image database

The problems of efficient data storage and data retrieval are important issues in the design of image database systems. A data structure called a 2-D string, which represents symbolic pictures preserving spatial knowledge, was proposed by Chang et al. It allows a natural way to construct iconic indexes for pictures. We proposed a data structure 2-D B-string to characterize the spatial knowledge embedded in images. It is powerful enough to describe images with partly overlapping or completely overlapping objects without the need of partitioning objects. When there exist a large volume of complex images in the image database, the processing time for image retrieval is tremendous. It is essential to develop efficient access methods for retrieval. In this paper, access methods, to different extents of precision, for retrieval of desired images encoded in 2-D B-strings are proposed. The signature file acting as a spatial filter of image database is based on disjoint coding and superimposed coding techniques. It provides an efficient way to retrieve images in image databases.     

The Impact of Tangible User Interfaces on Designers' Spatial Cognition

ABSTRACT

Most studies on tangible user interfaces for the tabletop design systems are being undertaken from a technology viewpoint. Although there have been studies that focus on the development of new interactive environments employing tangible user interfaces for designers, there is a lack of evaluation with respect to designers' spatial cognition. In this research we study the effects of tangible user interfaces on designers' spatial cognition to provide empirical evidence for the anecdotal views of the effect of tangible user interfaces. To highlight the expected changes in spatial cognition while using tangible user interfaces, we compared designers using a tangible user interface on a tabletop system with 3D blocks to designers using a graphical user interface on a desktop computer with a mouse and keyboard. The ways in which designers use the two different interfaces for 3D design were examined using a protocol analysis method. The result reveals that designers using 3D blocks perceived more spatial relationships among multiple objects and spaces and discovered new visuo-spatial features when revisiting their design configurations. The designers using the tangible interfaces spent more time in relocating objects to different locations to test the moves, and interacted with the external representation through large body movements implying an immersion in the design model. These two physical actions assist in designers' spatial cognition by reducing cognitive load in mental visual reasoning. Further, designers using the tangible interfaces spent more time in restructuring the design problem by introducing new functional issues as design requirements and produced more discontinuities to the design processes, which provides opportunity for reflection and modification of the design. Therefore this research shows that tangible user interfaces changes designers' spatial cognition, and the changes of the spatial cognition are associated with creative design processes.     

Spatial Input for Temporal Navigation in Scientific Visualizations

Scientific-visualization tools can make time-varying simulations easier to understand. The growing efficiency of today's high-performance computers enables simulation of physical phenomena with a high temporal resolution. Consequently, visualization systems require efficient navigation in the temporal dimension. This 3D user interface employs direct-manipulation metaphors for temporal navigation in scientific visualizations. By interacting with objects using their 3D trajectory, users can navigate in time by specifying spatial inputs. This article is part of a special issue on 3D user interfaces.     

Mobile robot navigation using the range-weighted Hough transform

Accurate navigation of a mobile robot in cluttered rooms using a range-measuring laser as a sensor has been achieved. To extract the directions and distances to the walls of the room the range-weighted Hough transform is used. The following experimental results are emphasized: The robot extracts the walls of the surrounding room from the range measurements. The distances between parallel walls are estimated with a standard deviation smaller than 1 cm. It is possible to navigate the robot along any preselected trajectory in the room. One special case is navigation through an open door detected by the laser. The accuracy of the passage is 1 cm at a speed of 0.5 m/s. The trajectory is perpendicular to the wall within 0.5 degrees in angle. When navigating through corridors, the accuracy is better than 1 cm at 0.8 m/s-the maximum speed of the robot. Odometric data and laser measurements are combined using the extended Kalman filter. The size of the cluttered rectangular room and the position and orientation (pose) of the robot are estimated during motion. The extraction and the resulting navigation are very robust against both spurious measurements in the laser measurements and disturbing objects     

Automatic Lighting Design using a Perceptual Quality Metric

Lighting has a crucial impact on the appearance of 3D objects and on the ability of an image to communicate information about a 3D scene to a human observer. This paper presents a new automatic lighting design approach for comprehensible rendering of 3D objects. Given a geometric model of a 3D object or scene, the material properties of the surfaces in the model, and the desired viewing parameters, our approach automatically determines the values of various lighting parameters by optimizing a perception-based image quality objective function. This objective function is designed to quantify the extent to which an image of a 3D scene succeeds in communicating scene information, such as the 3D shapes of the objects, fine geometric details, and the spatial relationships between the objects.
Our results demonstrate that the proposed approach is an effective lighting design tool, suitable for users without expertise or knowledge in visual perception or in lighting design.     

The Role of 3-D Sound in Human Reaction and Performance in Augmented Reality Environments

Three-dimensional sound's effectiveness in virtual reality (VR) environments has been widely studied. However, due to the big differences between VR and augmented reality (AR) systems in registration, calibration, perceptual difference of immersiveness, navigation, and localization, it is important to develop new approaches to seamlessly register virtual 3-D sound in AR environments and conduct studies on 3-D sound's effectiveness in AR context. In this paper, we design two experimental AR environments to study the effectiveness of 3-D sound both quantitatively and qualitatively. Two different tracking methods are applied to retrieve the 3-D position of virtual sound sources in each experiment. We examine the impacts of 3-D sound on improving depth perception and shortening task completion time. We also investigate its impacts on immersive and realistic perception, different spatial objects identification, and subjective feeling of "human presence and collaboration". Our studies show that applying 3-D sound is an effective way to complement visual AR environments. It helps depth perception and task performance, and facilitates collaborations between users. Moreover, it enables a more realistic environment and more immersive feeling of being inside the AR environment by both visual and auditory means. In order to make full use of the intensity cues provided by 3-D sound, a process to scale the intensity difference of 3-D sound at different depths is designed to cater small AR environments. The user study results show that the scaled 3-D sound significantly increases the accuracy of depth judgments and shortens the searching task completion time. This method provides a necessary foundation for implementing 3-D sound in small AR environments. Our user study results also show that this process does not degrade the intuitiveness and realism of an augmented audio reality environment     

虚拟场景自动漫游的路径规划算法

采用机器人学中的运动规划算法得到大致路径,并对路径进行数次优化得到最终路径．用户无需直接控制位置与视角,仅需给出目标点,系统就会自动地完成整个漫游;漫游过程中摄像机不会与物体发生碰撞,并且给出的画面符合一些基本的美学原则．该算法基于场景的层次分解,并采用了高效的路径平滑与视角规划方法,使得整个规划过程需要的时间非常少,提高了算法的实用性．     

Efficiently computing and representing aspect graphs of polyhedralobjects

An efficient algorithm and a data structure for computing and representing the aspect graph of polyhedral objects under orthographic projection are presented. The aspect graph is an approach to representing 3-D objects by a set of 2-D views, for the purpose of object recognition. In this approach the viewpoint space is partitioned into regions such that in each region the qualitative structure of the line drawing does not change. The viewing data of an object is the partition of the viewpoint space together with a representative view in each region. The algorithm computes the viewing data for line drawings of polyhedral objects under orthographic projection     

Distortion visualization techniques for 3D coherent sets: A case study of 3D building property units

In the fields of 3D cadastre and 3D property management system, numerous building property objects are adjacent as primary property units assemble into a 3D coherent set. During visualization process of the coherent set, occlusion, obscure, mazy spatial relationships and relative location relationships among the units of the coherent set cause difficulty in observing and understanding the set and its units. Common 3D objects viewing method, such as rotation and navigation obtaining desired visualization effects through adjusting the view angle and position of the camera's field of view, provides weak interactive experience and orientation control for the coherent set because of the neighbour relationships of the 3D objects inside the set. In this paper, a novel method is proposed to solve the prior problems with two basic distortion methods based on “focus + context” theory. The coherent set is first discretized into individual objects and changed them locations according to linear or orthogonal function, while keeping their relative location and dual topological relationships. To maintain both global context awareness (topology and locations) of 3D coherent set and highlight effect of the focus 3D building property object, three evaluation indexes are adopted to assess the corresponding distortion results. A case study based on the real clustered 3D property in Shenzhen was conducted to evaluate the performance of distortion functions, the result shows that the method proposed in this article can not only expand the visual area of focused object and create a clear line of sight (LOS) to the focal object previously obscured, but also maintain verticality and proximity in some degree to facilitate understand the spatial occupation and distribution of whole coherent objects.     

Why not make interfaces better than 3D reality?

Many constrained interfaces are designed to be simpler than the real world by restricting movement, limiting interface actions, and keeping interface objects in a plane. However, the strong utility of pure 3D interfaces for medical, architectural, product design, and scientific visualization means that interface design for pure 3D remains an important challenge. An intriguing possibility is that enhanced 3D interfaces might offer simpler navigation, more compelling functionality, safer movements, and less occlusion, than 3D reality, especially for information exploration and visualization tasks. Such features can enable superhuman capabilities such as faster-than-light teleportation, flying through objects, and X-ray vision. Enhanced 3D interfaces might have supernatural tools such as magic wands for instantly shrinking, enlarging, duplicating, or sending objects and enchanted environments that provide error prevention, history keeping, and programming-by-demonstration. Playful game designers and creative application developers have already pushed the technology further than those who seek merely to mimic reality. Advanced designs are marked by their support of rapid situation awareness through effective overviews, reduced numbers of actions to accomplish tasks; and prompt, meaningful feedback for user actions. This article reviews these clever enhanced 3D-design features and encourages approaches that facilitate user tasks rather than mimic reality.     

New Devices for 3D Pose Estimation: Mantis Eyes,Agam Paintings,Sundials, and Other Space Fiducials

Several unconventional ideas for viewer/camera pose estimation are discussed. The methods proposed so far advocate the use of advanced image processing for identification and precise location of calibration objects in the images acquired, and base pose recovery on the identification of the viewing dependent deformations of these objects. We propose to more fully exploit the freedom in the design of space fiducials or calibration objects showing that we can build objects whose images directly encode, in easily identifiable gray-level/color or temporal patterns, the pose of their viewer. We also show how to construct high-precision fiducials, which can determine a viewing direction quite accurately when it is known to lie within a relatively narrow range.     

Wide baseline image registration with application to 3-D face modeling

Establishing correspondence between features in two images of the same scene taken from different viewing angles is a challenging problem in image processing and computer vision. However, its solution is an important step in many applications like wide baseline stereo, three-dimensional (3-D) model alignment, creation of panoramic views, etc. In this paper, we propose a technique for registration of two images of a face obtained from different viewing angles. We show that prior information about the general characteristics of a face obtained from video sequences of different faces can be used to design a robust correspondence algorithm. The method works by matching two-dimensional (2-D) shapes of the different features of the face (e.g., eyes, nose etc.). A doubly stochastic matrix, representing the probability of match between the features, is derived using the Sinkhorn normalization procedure. The final correspondence is obtained by minimizing the probability of error of a match between the entire constellation of features in the two sets, thus taking into account the global spatial configuration of the features. The method is applied for creating holistic 3-D models of a face from partial representations. Although this paper focuses primarily on faces, the algorithm can also be used for other objects with small modifications.     

Bellcore's user-centred-design support centre

Abstract

Bellcore recently replaced its small laboratory that was designed primarily for formal testing of software usability. The new facility is a suite of rooms that handles multiple, independent activities. More importantly, the new space is a manifestation of our philosophy that the best approach to interface design is the cultivation of eclectic design practices early in and throughout the software development process. To that end, the new lab supports other kinds of user-centred design (UCD) activities in addition to formal testing of computerized prototypes of software interfaces. To encourage participatory design, nearly all the rooms are large enough for design meetings, contain entire walls of movable whiteboards, and have small tables so design teams can huddle over paper prototypes and task layouts. In this article we describe the new lab, the rationales behind its features, and the process by which it was designed.     

The effects of cast shadows and stereopsis on performing computer-generated spatial tasks

More powerful computer hardware and software has enabled the development of numerous depth-cue techniques to depict the three-dimensional (3D) characteristics of computer-generated imagery. Particularly, the role of stereoscopic viewing in promoting the depth perception of objects in 3D space has been widely studied. However, there has been little study of the use of cast shadows in this context, and few investigations of how computer-generated depth cues are perceptually integrated. To investigate these issues, subjects: 1) position a sphere to complete a directional vector/vector segment extending in space and 2) resize a sphere to match the perceived size of a second sphere displaced in space. Task accuracies and response times are recorded under the following conditions: 1) stereoscopic, and monoscopic, scene viewing; 2) objects casting zero, or one shadow; 3) flat, and zig-zag, background surface shapes; and 4) solid and checkerboard background surface textures. The results suggest that, of the cues considered, stereo viewing has a consistently beneficial effect on positioning and resizing spheres in depth. However, objects casting shadows improve positioning accuracy to a level afforded by stereo viewing. Finally, more complex scene backgrounds impair positioning and resizing task performances. Implications for the design of effective 3D user interfaces are discussed.