1,721,226 research outputs found
MATCHING OF HIGH RESOLUTION OPTICAL DATA TO A SHADED DEM
No full textOne of the first essential steps in the analysis of satellite imagery is the orthorectification of the images. Orthorectification without ground control points (GCPs) using only the ephemeris and attitude data provided by the satellite operator provides an absolute accuracy of about 20 m to 1 km (depending on the satellite), which can be improved by measuring precise GCPs. In this paper, a method to obtain GCPs from an existing digital elevation model (DEM) is described and assessed. Since at least the SRTM DEM is available worldwide, DEMs could serve as a valuable additional source for the generation of GCPs. Furthermore, several planned and ongoing missions will increase the availability and accuracy of DEMs or stereo imagery respectively, e.g. ALOS, Tandem-X, etc
Stereo Evaluation of CARTOSAT-1 Data Summary of DLR Results During CARTOSAT-1 Scientific Assessment Program
No full textThe Remote Sensing Technology Institute (IMF) of the German Aerospace Center (DLR) has more than 20 years of history in developing spaceborne stereo scanners and the corresponding stereo evaluation software systems. It takes part in the CARTOSAT-1 Scientific Assessment Program (C-SAP) as a principal investigator for German (Southeast Bavaria) and Spanish (Catalonia) test sites and as a Co-I for a French test site (Mausanne-les-Alpilles). A rich variety of landscapes is present in these three test sites. In all cases ground truth in form of GCP (or orthoimages of high resolution) and DTM/DSM (digital terrain or surface models) of sufficient accuracy have been delivered by the principal investigators.Rational polynomial functions (RPC) are provided by the distributing Indian agency (Space Applications Centre (SAC) of ISRO, Ahmedabad) as a universal sensor model for each scene. The inherent absolute orientation accuracy of the RPC models in the CARTOSAT-1 stereo imagery used here turned out to be around 100 m (normally). Thus, to exploit the high resolution of 2.5 m, RPC have to be corrected via the available ground truth. It is shown that the correction by an affine transformation is necessary in order to achieve sub-pixel accuracy in the stereo evaluation of full scenes. The remaining standard deviations of the residuals in image space during RPC correction are about 0.5-1 pixel in ground control points (GCP). Stereo evaluation is done by DLR processing software. Hierarchical intensity based matching and subsequent region growing are used to automatically derive a dense set of stereo tie points. An effective blunder reduction is based upon bi-directional LSM, quasi-epipolar reprojection of the tie points, and control of residuals in stereo forward intersection. Shifts between aft/fore orthoimages are found to be in sub-pixel range. DSM accuracy assessment is done via the statistics of height differences compiled by the forward intersection software. This is sufficient if accurate GCP for RPC correction are available. For direct comparison of the generated DSM with the reference DTM/DSM a 3D shift is estimated via least squares adjustment and mean and standard deviations of the DTM/DSM differences after shifting are provided. In summary, standard deviations of 2-4 m are achieved
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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