The History of the Cluster Heat Map

Wilkinson, Leland; Friendly, Michael

doi:10.1198/tas.2009.0033

Cited by 703 publications

(395 citation statements)

References 26 publications

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“…Figure 8 shows a visualization of the categories, that is, a heat map in the voxel grid. The voxel color represents the type of occupation and changes in occupation (Wilkinson & Friendly, 2009). …”

Section: Methodsmentioning

confidence: 99%

A high‐resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data

Hess

Härdtle

Kunz

et al. 2018

Ecology and Evolution

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Forest canopies and tree crown structures are of high ecological importance. Measuring canopies and crowns by direct inventory methods is time‐consuming and of limited accuracy. High‐resolution inventory tools, in particular terrestrial laser scanning (TLS), is able to overcome these limitations and obtain three‐dimensional (3D) structural information about the canopy with a very high level of detail. The main objective of this study was to introduce a novel method to analyze spatiotemporal dynamics in canopy occupancy at the individual tree and local neighborhood level using high‐resolution 3D TLS data. For the analyses, a voxel grid approach was applied. The tree crowns were modeled through the combination of two approaches: the encasement of all crown points with a 3D α‐shape, which was then converted into a voxel grid, and the direct voxelization of the crown points. We show that canopy occupancy at individual tree level can be quantified as the crown volume occupied only by the respective tree or shared with neighboring trees. At the local neighborhood level, our method enables the precise determination of the extent of canopy space filling, the identification of tree–tree interactions, and the analysis of complementary space use. Using multitemporal TLS data recordings, this method allows the precise detection and quantification of changes in canopy occupancy through time. The method is applicable to a wide range of investigations in forest ecology research, including the study of tree diversity effects on forest productivity or growing space analyses for optimal tree growth. Due to the high accuracy of this novel method, it facilitates the precise analyses even of highly plastic individual tree crowns and, thus, the realistic representation of forest canopies. Moreover, our voxel grid framework is flexible enough to allow for the inclusion of further biotic and abiotic variables relevant to complex analyses of forest canopy dynamics.

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Section: Methodsmentioning

confidence: 99%

A high‐resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data

Hess

Härdtle

Kunz

et al. 2018

Ecology and Evolution

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show abstract

“…In a term-document matrix the features are index terms (terms that are semantically charged), whereas instances are documents (a text, a web page, a blog entry, etc.). If we rearrange the rows and columns in the matrix such that related terms will be near each other, and clusters of similar documents will also be nearby column vectors, we arrive at a visual reflection of a statistical model, a heat map of the matrix (Wilkinson and Friendly, 2009). The underlying idea of a heat map is a seriation of both the row and the column space.…”

Section: Mapping Evolving Semantic Structuresmentioning

confidence: 99%

“…In other words the overall structure is not an arbitrary ordering of row and column cluster trees. Certain types of two-way seriation are also called heat maps (Wilkinson and Friendly, 2009). …”

Section: Mapping Evolving Semantic Structuresmentioning

confidence: 99%

Demonstrating conceptual dynamics in an evolving text collection

Daranyi

Wittek

2013

J Am Soc Inf Sci Tec

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Based on real world user demands, we demonstrate how animated visualisation of evolving text corpora displays the underlying dynamics of semantic content. To interpret the results, one needs a dynamic theory of word meaning. We suggest that conceptual dynamics as the interaction between kinds of intellectual, emotional etc. content, and language, is key for such a theory. We demonstrate our methodology by two-way seriation which is a popular technique to analyse groups of similar instances and their features, as well as the connections between the groups themselves. The two-way seriated data may be visualised as a two-dimensional heat map or as a three-dimensional landscape where colour codes or height correspond to the values in the matrix. In this paper we focus on two-way seriation of sparse data in the Reuters-21568 test collection. To achieve a meaningful visualisation thereof we introduce a compactly supported convolution kernel similar to filter kernels used in image reconstruction and geostatistics. This filter populates the high-dimensional sparse space with values that interpolate nearby elements, and provides insight into the clustering structure. We also extend two-way seriation to deal with online updates of both the row and column spaces, and, combined with the convolution kernel, demonstrate a three-dimensional visualisation of dynamics.

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“…Furthermore, to understand school electricity consumption data before the analysis, the data is visualized in a cluster heat map. A cluster heat map is a graphical representation of data where the individual values contained in a matrix are represented as colors taken from a color scale [17].…”

Section: Data Visualizationmentioning

confidence: 99%

A New Anomaly Detection System for School Electricity Consumption Data

Cui

Wang

2017

Information

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Anomaly detection has been widely used in a variety of research and application domains, such as network intrusion detection, insurance/credit card fraud detection, health-care informatics, industrial damage detection, image processing and novel topic detection in text mining. In this paper, we focus on remote facilities management that identifies anomalous events in buildings by detecting anomalies in building electricity consumption data. We investigated five models within electricity consumption data from different schools to detect anomalies in the data. Furthermore, we proposed a hybrid model that combines polynomial regression and Gaussian distribution, which detects anomalies in the data with 0 false negative and an average precision higher than 91%. Based on the proposed model, we developed a data detection and visualization system for a facilities management company to detect and visualize anomalies in school electricity consumption data. The system is tested and evaluated by facilities managers. According to the evaluation, our system has improved the efficiency of facilities managers to identify anomalies in the data.

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The History of the Cluster Heat Map

Cited by 703 publications

References 26 publications

A high‐resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data

A high‐resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data

Demonstrating conceptual dynamics in an evolving text collection

A New Anomaly Detection System for School Electricity Consumption Data

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