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DiaML code example, diagram description - stacked, linear bar chart, using green rectangles with stroke
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Maps employing thematic map symbols, such as bar or pie charts are often used and constitute a standard method of displaying thematic data with geospatial reference. With the increasing popularity of virtual earth technologies, such as Google Earth, these methods of displaying thematic data are adopted for virtual 3D environments. The efficient cre...
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... employing thematic map symbols, such as bar or pie charts are often used and constitute a standard method of displaying thematic data with geospatial reference. With the increasing popularity of virtual earth technologies, such as Google Earth, these methods of displaying thematic data are adopted for virtual 3D environments. The efficient creation of data graphics for the integration into virtual 3D environments calls for suitable data structures and processes. The research presented in this paper shows the development of a prototype for the generation of data graphics. The developed prototype is based on several existing technologies. The representation of the diagrams is described using a profile of DiaML (Diagram Markup Language) (Schnabel 2007). As geo data input format we devised a simple XML format. The formal diagram description in DiaML and the thematic data with spatial references are then transformed in one of three output formats (X3D, SVG and KML and COLLADA) depending on control parameters which are specified in a separate document. The different templates of the XSL transformation are kept as generic as possible to make them reusable for different diagram types and output formats. The prototype has successfully been tested with different sets of uni- and multi-dimensional data. Thematic maps employing 2D data graphics or thematic map symbols, such as bar or pie charts, for the display of statistical data or other abstract data values are often used and constitute a standard method of displaying thematic data with geospatial reference. With the increasing popularity of virtual earth technologies, such as Google Earth or Bing Maps 3D, these methods of displaying thematic data are adopted for virtual 3D environments (e.g. Sgrillo 2009 or Sandvik 2009). We believe that the visual combination of data graphics with the quite naturally perceived virtual 3D landscape, in which the data was collected in, is a valuable complement to traditional 2D representations. Ongoing research (Bleisch et al. 2008) evaluates the appropriateness of such a combination in different experimental and applied settings. The goal of the research presented in this paper is to define suitable data structures and processes for an efficient creation of data graphics for the integration into virtual 3D environments. The processes need to be flexible enough to be adaptable to different text-based 3D display formats and standards, data and diagram types. This paper presents the development of a prototype that fulfils the above mentioned requirements. It illustrates the difficulties and the developed solution and presents the results from evaluating the prototype with different data sets, 3D display formats and diagram types. The diagram generation prototype is developed based on several existing technologies. The core of the prototype is a XSL (eXtensible Stylesheet Language) transformation combining the thematic geo data which is to be displayed with the formal description of the diagrams (Figure 1). The output of the transformation process is one of three different 3D display formats. The input geo data and its associated attribute values need to be available in a generic format. We devised a simple XML (eXtensible Markup Language) format as input of the transformation process. A number of XML elements allow the description of the input geo data such as a spatial point reference for each data set, the attribute values and their description (Figure 2). The XML format is described using XMLSchema which allows validation of created input files. Using an XML format for the description of the input data has several advantages, for example, it is a text based format and easily generated out of most databases or other storage forms of existing geo data. The different diagram types are formally described using a profile of DiaML (Diagram Markup Language) (Schnabel 2007). DiaML is a XML language developed for the description of several different thematic map symbols and charts in 2D (Figure 3). It employs construction rules that parameterise different variations of diagrams. For the prototype development we use a profile of DiaML that is restricted to different bar charts. This is a necessity in order to keep the complexity of the prototype development manageable. However, it shall be possible to add further DiaML diagram definitions to the prototype in future developments phases. As the two input formats (the geo data XML file and the diagram description in DiaML) as well as several output 3D display formats and standards are text-based it makes sense to use XSLT (eXtensible Stylesheet Language Transformation) as processing language. For the prototype development we defined three output formats for the data ...
Citations
... It is a tree of connected bones and each of the bones create a new local coordinate system. Transformation of a point connected to a specific bone depends on transformation components of this bone and all parent transformations (Bleisch S., Burkhard J., 2009). Transformations can be presented with equation with transformation matrixes: ...
This paper describes WebGl-Based viewer for rendering 3D content for the purposes of online shopping. The paper addresses techniques for transforming, visualizing and interacting with 3D objects. Special attention was paid to efficiency, cross-platform and cross-browser implementation of the viewer. The main purpose was to provide realistic 3D view of online shop items which will enrich the user experience and increase the sales of the e-shops. The viewer is designed to be extended with mass-spring simulations on different browsers and platforms. Viewer provides full set of light model characteristics, 3D object transformations and animations, camera animation, multi-format import and export, desktop, iOS and Android support, object space and image space collision detection techniques and 3D human body customization.
... For the efficient generation of the above discussed bar and bar chart displays in virtual environments an XML (Extensible Markup Language, W3C 2010a) based framework was developed (Burkhard 2008, Bleisch, Burkhard & Nebiker 2009). It allows different data displays with bars as base elements to be created. ...
... The bar chart definition is done in a specific XML format defined by a subset of the diagram description XML Schema (W3C 2010d) developed by Schnabel (2007) in his thesis about different diagram signatures. The geodata, point data with associated attribute values, needs to be available in a simple XML format defined by an XML Schema (Burkhard 2008 (Bleisch, Burkhard & Nebiker 2009, Burkhard 2008. ...
The integration of various data sets into desktop based 3D virtual environments, such as the virtual globe Google Earth, is quickly achieved with today’s technological options. Nevertheless, we know little about the appropriateness of such representations. A number of research studies have looked at different aspects of 3D virtual environments, in particular interaction and navigation, but rarely at the use of virtual environments for data analysis. The visual combination of quantitative data with the three-dimensional virtual equivalent of the natural environment where a data set was collected may help the analysis of such data sets in regard to altitude and landform. Data sets demonstrating an interesting relationship between data and landscape may become increasingly available with the further development and application of sensor networks. The research summarised here aims to increase the understanding of the use of desktop based 3D virtual environments with a focus on the graphical representation of quantitative data through abstract symbols or graphics.
A mixed methods research approach is employed. Four different stages with different methodologies are combined to gain a holistic view regarding the goals of the study. The research stages are positioned along a ’bridge’ from experimental ’in vitro’ research to applied settings or ’in vivo’ case studies driven by increasing context, data and task complexity. In the first stage, the effectiveness and efficiency of 2D bars in 3D virtual environments as compared to 2D displays was tested. Experiment participants identified the larger of pairs of bars and compared their lengths. The research stages IIa and IIb tested 2D bars in virtual environments with more complex data and tasks. In stage IIa participants answered complex tasks, such as pattern identification, in regard to several single value bars while in stage IIb a more open insight reporting approach was employed to let participants explore bar charts representing more complex data aggregations. The reported insights were analysed regarding their complexity, plausibility and the participants’ confidence in them. In stage III a descriptive and explorative case study approach with three diverse cases including real world data sets and data experts was implemented to test and enhance the findings of the previous stages.
The results show that typical users are able to separate depth cues and distortions introduced by perspective viewing from absolute value changes in the representations of quantitative data in virtual environments when represented as 2D bars on billboards. While the users are able to relate multivariate data represented in virtual environments to altitude and landform, the 3D environment does not especially support this. Only insignificant variation between 2D representations and 3D visualisations are found. However, the different data sets and tasks influence the results. The participants’ answers are strongly guided by the tasks and some data sets are more successfully analysed in 3D, others in 2D. Generally, analysis of data in relation to altitude and landform is successful in either visualisation but participants do it less habitually than data analysis in relation to location and distribution. The data experts of stage III comment positively about the possibilities of the quantitative data visualisations in virtual environments. But the usefulness is dependent on visualisation completeness and on the data expert’s previous usage of visualisations for either communication and/or data exploration purposes. Displaying up to four variables at once is identified as maximum of acceptable data graphics complexity. Additionally, more interaction, such as switching on and off the reference frames of the bar charts, is requested. Navigation is imperative for data analysis in virtual environments.
Methodologically bridging between experimental ’in vitro’ and case study based ’in vivo’ research methods is appropriate as the results of each stage can inform the design of the following stages. Additionally, the outcomes of later stages lead to re-evaluations or different interpretation of earlier results as for the aspects of bar chart complexity, occlusion and use of reference frames. Thus, in combining different methods, particular strengths such as exclusion or inclusion of context can be added together and potential weaknesses, such as small numbers of data experts, overcome. A holistic understanding of the visualisation technique is gained but it is nevertheless possible to attend to details. The case studies indicate that it is difficult to capture the use of visualisation in real world settings as the kinds of data sets made available are likely to be well known, as they were in this study. Nevertheless, the results of stage III allow evaluating earlier findings in a more applied setting and explore further issues. For example, the data experts commented on improvements and further applications for the visualisations. This may serve as input to the design process of future visualisation prototypes.
