15344875
Albedo recovery using a photometric stereo approach
This paper describes a method for the estimation of surface reflectance values using a photometric stereo approach. Evaluations show that surfaces rendered with reflectance values calculated by the proposed method have more realistic appearances than those with constant albedo.
11144392
Integration of Photometric Stereo and Shape from Occluding Contours by Fusing Orientation and Depth Data
In this paper, we have investigated the fusion of surface data obtained by two different surface recovery methods. In particular, we have fused the depth data obtainable by shape from contours and local surface orientation data obtainable by photometric stereo. It has been found that the surface obtained by fusing orientation and depth data is able to yield more precision when compared with the surfaces obtained by either type of data alone.
5472476
Image Stitching - Comparisons and New Techniques
This work describes the steps involved in the generation of a panoramic image, i.e., image acquisition, image registration and image merging. Different approaches for each of these steps are discussed and compared. The resultant images from image registration and image merging are quantitatively evaluated to provide an indication to the performance of the different methods. The methods provided in this work can be used to generate panoramic images for the use of interactive panoramic viewing of images, architectural walk-through, and other applications associated with the modelling of 3D environments.
29297649
Shape from Photometric Stereo and Contours
In this work, we propose an alternative approach to 3D shape recovery by combining photometric stereo and shape from contours methods. Surfaces recovered by photometric stereo are aligned, adjusted and merged according to a preliminary 3D model obtained by shape from contours. Comparisons are conducted to evaluate the performances of different methods. It has been found that the proposed approach provides more accurate shape recovery than the photometric stereo and shape from contours methods.
18259111
An Empirical Study of Memory and Information Retrieval with a Spatial User Interface
The rapid advances in information retrieval, especially with visualisation-oriented user interface design, highlight the need for an understanding of the interplay between cognitive abilities of users and the design of visual user interfaces. In this study, we focus on two aspects of memory abilities of users in attempts to reveal their roles in facilitating information-seeking tasks. In particular, we study the relationships between associative memory and the use of a spatial user interface, and the relationship between visual memory and the same user interface. The design of the spatial user interface draws upon information visualisation techniques in order to highlight the strongest semantic relations in the search space. Two retrieval tasks were performed. While associative memory was strongly correlated with the first task, visual memory was negatively correlated with the second task. Both correlations were statistically significant. Implications for user interface design and suggestions for further empirical studies are also discussed.
11939689
Delineating the citation impact of scientific discoveries
Identifying the significance of specific concepts in the diffusion of scientific knowledge is a challenging issue concerning many theoretical and practical areas. We introduce an innovative visual analytic approach to integrate microscopic and macroscopic perspectives of a rapidly growing scientific knowledge domain. Specifically, our approach focuses on statistically unexpected phrases extracted from unstructured text of titles and abstracts at the microscopic level in association with the magnitude and timeliness of their citation impact at the macroscopic level. The H-index, originally defined to measure individual scientists. productivity in terms of their citation profiles, is extended in two ways: 1) to papers and terms as a means of dividing these items into two groups so as to replace the less optimal threshold-based divisions, and 2) to take into account the timeliness of the impact of knowledge diffusion in terms of the timing of citations and publications so that attention is particularly drawn towards potentially significant and timely papers. The selected terms are connected to higher-level performance indicators, such as measures derived from the H-index, in the form of decision trees. A top-down traversal of such decision trees provides an intuitive walkthrough of concepts and phrases that may underline potentially significant but currently still latent scientific discoveries. Timeliness measures can also help to identify institutions that are at the forefront of a research field. We illustrate how widely accessible tools such as Google Earth can be utilized to disseminate such insights. The practical significance for digital libraries and fostering scientific discoveries is demonstrated through the astronomical literature related to the Sloan Digital Sky Survey (SDSS).
27757598
Assessing the effectiveness of online asynchronous case method
This paper reports a field experiment that evaluates the use of the case method in an online asynchronous learning (OAL) environment. Our findings suggest that OAL should be used to promote students' participation, rather than cognitive learning gains. Teaching the case method in F2F environment can help learners achieve higher cognitive learning gains.
11234391
Augmenting user interfaces for digital libraries with virtual reality
The paper describes a generic approach to the development of a virtual reality based user interface for a collection of digital documents. We emphasise the role of intrinsic inter document relationships in structuring and visualising a digital library. We integrate techniques from information retrieval and structure modelling for visualising the ACM Hypertext Compendium. Salient relationships in the Compendium are extracted and visualised as associative networks. A virtual reality based user interface is automatically generated in VRML. We show that the spatial layout of the virtual world highlights prominent structural patterns in the Compendium. We discuss design issues concerning seamlessly browsing the digital library in a 3D virtual world and how users can search and browse within a consistent spatial metaphor provided by the user interface.
45162382
Efficient priority-first search maximum-likelihood soft-decision decoding of linear block codes
The authors present a novel and efficient maximum-likelihood soft-decision decoding algorithm for linear block codes. The approach used here converts the decoding problem into a search problem through a graph that is a trellis for an equivalent code of the transmitted code. A generalized Dijkstra's algorithm, which uses a priority-first search strategy, is employed to search through this graph. This search is guided by an evaluation function f defined to take advantage of the information provided by the received vector and the inherent properties of the transmitted code. This function f is used to reduce drastically the search space and to make the decoding efforts of this decoding algorithm adaptable to the noise level. For example, for most real channels of the 35 000 samples tried, simulation results for the (128,64) binary extended BCH code show that the proposed decoding algorithm is fifteen orders of magnitude more efficient in time and in space than that proposed by Wolf (1978). Simulation results for the (104, 52) binary extended quadratic residue code are also given. >