1,720,957 research outputs found
Analyses of the errors characteristics in land cover maps: Aggregation of errors for individual land cover class confusions
No full textMethodology and EO data behind land cover maps are improving constantly so as the land cover maps quality, and this is known thanks to the accuracy assessment. Accuracy assessment is not only useful for map users to understand how reliable the map is, but also feedback to the producer about how much the map can be improved.
For accuracy assessment, classified data are compared to reference data. Reference data can be a result of a field survey or visual inspection of satellite imagery or orthophoto, but also another land cover map. The first two sources of reference data are considered more reliable, however, the advantage of having another land cover map as a reference data is that the data are continuous in the study area, and not samples like in other cases. This advantage was exploited in this work to develop a methodology for analyzing the aggregation of the errors in the land cover map for each confusion type (confusion type is a combination of the two confused classes). Aggregation is a proxy to determine if an error of certain confusion type is systematic or random. If the confusion type is not random, it is possible to tune parameters of classification algorithm or increase training samples to improve results of the specific class involved in non-random confusion.
Before the comparison of the reference and classified map they need to go through preprocessing to have the same class codes, reference system, and resolution. Afterward, all the pixels on the borders between classes in classified map and reference maps should be masked. This is necessary to exclude possible mixed pixel and georeferencing error since usually they are not expected to be aggregated and thus can affect overall aggregation of the confusion type. Furthermore, a confusion map between classification and reference can be computed. Values in the confusion map can be obtained by merging the value of reference data and classification data (e.g. 1020 is confusion between class 10 in reference and class 20 in classified data) through arithmetic operations on the rasters. Based on this map it was possible to estimate how aggregated each type of confusion is. In this methodology aggregation is estimated as the ratio between the number of joins of a confusion type with itself and the total number of joins with all the classes including itself. The equation originates from FRAGSTATS software (https://www.umass.edu/landeco/research/fragstats/fragstats.html), but it is adjusted from 4-cell to the 8-cell neighborhood. Borders are double counted. Number of joins was extracted through arithmetic operations from the results of r.neigborhood GRASS GIS module (interspersion method) that also uses number of joins for getting interspersion of a pixels. All the operations were done by employing different modules of GRASS GIS software through Python (PyGRASS, (https://grass.osgeo.org/grass78/manuals/libpython/pygrass_index.html) employed on CINECA HPC - Galileo (http://www.hpc.cineca.it/).
For exemplifying the results Figure ‘Confusion type aggregation’ contains results of the above described procedure for two confusion types. Data used for calculation of confusion types are ‘GlobeLand30’ (GL30, http://www.globallandcover.com/) for 2015 and 'S2 prototype LC map at 20m of Africa 2016' (CCI S2 Prototype, http://2016africalandcover20m.esrin.esa.int/) in Rwanda, Africa. The GL30 map represent classification results which was compared to the CCI S2 Prototype reference map. In the figure it is possible to see confusion types: Confusion of class Cultivated area with Water bodies and Shrubland with Forest. Aggregation of former confusion type is estimated to be 95%, while aggregation of latter confusion type is 79%. The figure confirms what numbers are showing. The aggregation of the Cultivated area – Water bodies confusion is stronger than Shrubland-Forest confusion.
Confusion types with high aggregation indicate that cause of the confusion is systematic. Since two land cover maps are compared during accuracy assessment, in the first place we must be sure that cause of error is not due to mismatching of legends. Then map producer can investigate if number of training samples was sufficient, or if tuning of the classification algorithm can be adjusted.
This work focuses only in the estimation of the aggregation, however for complete accuracy assessment it is necessary to take into consideration error matrix and associated indexes (e.g Overall accuracy, User’s Accuracy, Producer’s accuracy, etc.).
Although use of existing land cover maps for validation is not the most reliable technique it can have its advantages
That is the only type of reference data that is continuous and therefore allows analyses of class confusion aggregation and thus separation of confusion to random and systematic
If the confusion is strongly aggregated it is an indicator that classification might be wrong and that it is necessary to tune classification algorithm or increase number of training samples involved into classification of the class concerne
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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