1,720,984 research outputs found
Attention-based 3D convolutional neural network for crop boundary detection in high-resolution satellite image time series
No full textAdvancements in satellite missions have dramatically improved the monitoring of vegetation and agricultural activities through high-resolution Satellite Image Time Series (SITS), providing enhanced insights into crop dynamics and boundary identification. However, traditional UNet-based Convolutional Neural Networks (CNNs), though effective for crop mapping, often struggle to capture the full spatio-temporal complexities inherent in these datasets, particularly when it comes to detecting less distinct boundaries. To address these challenges, a novel attention-based residual 3D UNet architecture has been developed, incorporating a spatial-temporal attention mechanism that enhances the networks ability to represent spatial and temporal features. This attention mechanism is strategically implemented in the decoder, where it gathers information from both the encoder and the previous layer within the decoder. This dual-source integration allows the model to focus more effectively on relevant crop boundaries during training, assigning greater weight to these crucial areas while reducing the emphasis on non-crop regions. The residual 3D UNet architecture adeptly handles the intricate spatial-spectral-temporal correlations present in SITS, enabling more accurate and simultaneous modelling of both spatial and temporal information. The proposed method is evaluated on an area with small-scale crop fields in Germany using Sentinel-2 SITS data collected over several months, this approach demonstrated superior performance in boundary detection compared to existing state-of-the-art methods, particularly in scenarios where boundaries are less clearly defined
Crop Field Boundary Detection Using 3d Convolutions in Multi-Spectral Multi-Temporal Hr Satellite Images
No full textThe advent of new satellite missions offering high spatial, spectral, and temporal resolution has significantly enhanced the possibility to monitor vegetation and agricultural practices. The High-resolution (HR) Satellite Image Time Series (SITS) enables a deeper understanding of crop fields behavior and precise boundary detection. While Convolutional Neural Networks (CNNs) have demonstrated effectiveness in crop fields-related analyses, existing methods for crop boundary detection often focus on mono-temporal image analysis, overlooking valuable multi-temporal information in SITS. To address this gap, we propose the utilization of a UNet-based three-dimensional (3D) CNN architecture, allowing for the simultaneous modeling of spatial-temporal information within multi-spectral multi-temporal SITS. Additionally, we explore various CNN-based U-Net models to further validate the proposed approach in accurately detecting crop field boundaries. The method is evaluated in an agricultural area in Germany using 12 Sentinel-2 Level-2A images and has demonstrated promising results
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
Land cover classification map of Germany's agricultural area based on Sentinel-2A data from 2016
No full textOvercoming the obstacle of frequent cloud coverage in optical remote sensing data is essential for monitoring dynamic land surface processes from space. APiC, a novel adaptable pixel-based compositing and classification approach, is especially designed to use high resolution spatio-temporal space-borne data.
Here, pixel-based compositing is used separately for training data and prediction data. First, cloud-free pixels covered by reference data are used within adapted composite periods to compile a training dataset. The compiled training dataset contains samples of spectral reflectances for respective land cover classes at each composite period. For land cover prediction, pixel-based compositing is then applied region-wide. Multiple prediction models are used based on temporal subsets of the compiled training dataset to dynamically account for cloud coverage at pixel level. Thus we present a data-driven classification approach which is applicable in regions with different weather conditions, species composition and phenology.
The capability of our method is demonstrated by mapping 19 land cover classes across Germany for the year 2016 based on Sentinel-2A data. Since climatic conditions and thus plant phenology change on a large scale, the classification was carried out separately in six landscape regions of different biogeographical characteristics. The study drew on extensive ground validation data provided by the federal states of Germany.
For each landscape region, composite periods of different lengths have been established, which differ regionally in their temporal arrangement as well as in their total number, emphasising the advantage of a flexible regionalised classification procedure. Using a random forest classifier and evaluating outcomes with independent reference data, an overall accuracy of 88% was achieved, with particularly high classification accuracy of around 90% for the major land cover types. We found that class imbalances have significant influence on classification accuracy. Based on multiple temporal subsets of the compiled training dataset, over 10,000 random forest models were calculated and their performance varied considerably across and within landscape regions. The calculated importance of composite periods show that a high temporal resolution of the compiled training dataset is necessary to better capture the different phenology of land cover types.
In this study we demonstrate that APiC, due to its data-driven nature, is a very flexible compositing and classification approach making efficient use of dense satellite time series in areas with frequent cloud coverage. Hence, regionalisation can be given greater focus in future broad-scale classifications in order to facilitate better integration of small-scale biophysical conditions and achieve even better results in detailed land cover mapping
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
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