Figure 6 - uploaded by Burkhard Wünsche
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Visualization of CT scan of two feet (16Bit, 256 × 256 × 250 voxels) provided by Osirix and visualized using our spreadsheet-like interface. The bottom left graph shows the original histogram (red) and its main peaks identified with the Douglas-Peucker algorithm (black).
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The effectiveness of direct volume rendered images depends on finding transfer functions which emphasize structures in the underlying data. In order to support this process, we present a spreadsheet-like construc- tive visual component-based interface, which also allows novice users to efficiently find meaningful transfer functions. The interface u...
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... Neural network based techniques are then used to generate the TF. A spreadsheet-like interface based on Douglas-Peucker algorithm is presented in [Liu et al. 2010]. ...
p>Transfer Function (TF) generation is a fundamental problem in Direct Volume Rendering (DVR). ATF maps voxels to color and opacity values to reveal inner structures. Existing TF tools are complex and unintuitive for the users who are more likely to be medical professionals than computer scientists. In this paper, we propose a novel image-centric method for TF generation where instead of complex tools, the user directly manipulates volume data to generate DVR. The user’s work is further simplified by presenting only the most informative volume slices for selection. Based on the selected parts, the voxels are classified using our novel Sparse Nonparametric Support Vector Machine classifier, which combines both local and near-global distributional information of the training data. The voxel classes are mapped to aesthetically pleasing and distinguishable color and opacity values using harmonic colors. Experimental results on several benchmark datasets and a detailed user survey show the effectiveness of the proposed method.</p
... In addition, the program could suggest examples of successful visualizations as a starting template (cf. Liu et al. [32] or Alexa et al. [33] ). Machine learning could be employed to guide the user or filter what they see (e.g., see Gotz et al. [34] or Keck and Groh [35] ). ...
Visualization has evolved into a mature scientific field and it has also become widely accepted as a standard approach in diverse fields, including physics, life sciences, and business intelligence. However, despite its successful development, there are still many open research questions that require customized implementations in order to explore and establish concepts, and to perform experiments and take measurements. Many methods and tools have been developed and published but most are stand-alone prototypes and have not reached a mature state that can be used in a reliable manner by collaborating domain scientists or a wider audience. In this study, we discuss the challenges, solutions, and open research questions that affect the development of sophisticated, relevant, and novel scientific visualization solutions with minimum overheads. We summarize and discuss the results of a recent National Institute of Informatics Shonan seminar on these topics.
... Several such approaches exist, which can be subsumed by the term 'visualization by example' (B. Liu, Wunsche, and Ropinski, 2010). All such approaches allow one to select a desired view V (P i ) from a range of candidates, the main distinction being how these candidates are picked from the view space calV and how V is presented to the user. ...
Eye-tracking tools estimate the locations in a scene where a user is fixating on. They are used in various domains including human-computer interaction (HCI) and learning transfer. As an example, gaze-based text entry allows interacting with computing systems remotely without touching the interface. They are also used to comprehend the visual behaviors of a pilot searching for information in a cockpit. However, a number of barriers still exists and makes these devices less accurate and difficult to use in daily activities. One of these problems is the shift between the actual and the estimated position of the user’s point-of-regard, which systematically comes from the eye-tracking systems’ accuracy. Following recent advances, there is an increasing interest in affordable systems that have the potential to be more accurate and, researchers are continually investigating novel approaches.This thesis covers different issues of eye movement research. It proposes the use of novel approaches as a step towards overcoming these accuracy issues. More specifically, we introduce novel strategies for detecting mapping functions for gaze estimation and calibration-free gaze interaction. In addition to proposing frameworks and strategies for improving accuracy, new calibration procedures and patterns are also revealed and discussed. In this thesis, we address these issues in three different ways: calibration and mapping functions, Human-computer Interaction using the eyes, visualization and exploration. We present four main contributions. First, we present a new method for calibrating state-of-the-art eye trackers with better accuracy. Second, we present a new gaze-based authentication method which works without any prior calibration, and can be extended to any alphanumeric-based input modality. Third, we present an uncertainty visualization approach. Finally, a method of analyzing eyemovements data and aircraft trajectories using a novel brushing technique is proposed.
... König et al. [16] proposed a similar approach by providing the user with an arranged display of previews, allowing him to choose a region to work as an initial set of parameters for fine-tuning. While most work on transfer function design rely on image processing techniques [4,9,11,15,[18][19][20]23,26], there have been some interesting ideas regarding sketch-based approaches. Differences concern exposing the user to 1D or 2D histograms, the use of thumbnails, providing intensity and gradient transfer functions or even enabling direct transfer function design. ...
Visual quality of volume rendering for medical imagery strongly depends on the underlying transfer function. Conventional Windows–Icons–Menus–Pointer interfaces typically refer the user to browse a lengthy catalog of predefined transfer functions or to pain-staking refine the transfer function by clicking and dragging several independent handles. To turn the standard design process less difficult and tedious, this paper proposes novel interactions on a sketch-based interface that supports the design of 1D transfer functions via touch gestures to directly control voxel opacity and easily assign colors. User can select different types of transfer function shapes including ramp function, free hand curve drawing, and slider bars similar to those of a mixing table. An assorted array of thumbnails provides an overview of the data when editing the transfer function. User performance is evaluated by comparing the time and effort necessary to complete a number of tests with sketch-based and conventional interfaces. Users were able to more rapidly explore and understand volume data using the sketch-based interface, as the number of design iterations necessary to obtain a desirable transfer function was reduced. In addition, informal evaluation sessions carried out with professionals (two senior radiologists, a general surgeon and two scientific illustrators) provided valuable feedback on how suitable the sketch-based interface is for illustration, patient communication and medical education.
... Neural network based techniques are then used to generate the TF. A spreadsheet-like interface based on Douglas-Peucker algorithm is presented in [Liu et al. 2010]. ...
Transfer Function (TF) generation is a fundamental problem in Direct Volume Rendering (DVR). A TF maps voxels to color and opacity values to reveal inner structures. Existing TF tools are complex and unintuitive for the users who are more likely to be medical professionals than computer scientists. In this paper, we propose a novel image-centric method for TF generation where instead of complex tools, the user directly manipulates volume data to generate DVR. The user's work is further simplified by presenting only the most informative volume slices for selection. Based on the selected parts, the voxels are classified using our novel Sparse Nonparametric Support Vector Machine classifier, which combines both local and near-global distributional information of the training data. The voxel classes are mapped to aesthetically pleasing and distinguishable color and opacity values using harmonic colors. Experimental results on several benchmark datasets and a detailed user survey show the effectiveness of the proposed method.
... Separately, exploratory visualization approaches have used the view space in a foresighted manner to sketch possible next steps along the visual exploration path. Several such approaches exist, which can be subsumed by the term 'visualization by example' [70]. All such approaches allow one to select a desired view V(P i ) from a range of candidates, the main distinction being how these candidates are picked from the view space calV and how V is presented to the user. ...
Understanding large multidimensional datasets is one of the most challenging problems in visual data exploration. One key challenge that increases the size of the exploration space is the number of views that one can generate from a single dataset, based on the use of multiple parameter values and exploration paths. Often, no such single view contains all needed insights. The question thus arises of how we can efficiently combine insights from multiple views of a dataset. We propose a set of techniques that considerably reduce the exploration effort for such situations, based on the explicit depiction of the view space, using a small multiple metaphor. We leverage this view space by offering interactive techniques that enable users to explicitly create, visualize, and follow their exploration path. This way, partial insights obtained from each view can be efficiently and effectively combined. We demonstrate our approach by applications using real-world datasets from air traffic control, software maintenance, and machine learning.
... Visualization design, i.e., the process of creating a suitable visual representations for a dataset and task at hand, is a complex creative procedure [1]. As a means to reduce the complexity that is exposed to the user, output-driven visualization design approaches, such as visualization by example [2] or visualization by analogy [3], have been developed. They utilize ways to configure visualization designs, which allow for defining a visual representation in an illustrative manner by exemplifying its result. ...
... These samples are then shown as previews in a gridded spreadsheet or on a continuous canvas spanned by the independent axes. Examples are manifold and include spreadsheet-like interfaces for choosing transfer functions [2,47,48], selecting viewpoints [49], picking data placements [50], adjusting color maps and isovalues [51], and even for manipulating color distributions [52]. Moreover, such interfaces can act as visual histories that exemplify each interactive adjustment with a respective visualization instance within the configuration space [53]. ...
Generating the "right" visual representation for the data and task at hand remains a standing challenge in visualization research and practice. A variety of different approaches to produce visual representations have been proposed in the past, including such noteworthy instances as visualization by example and visualization by analogy. With this paper, we add a new twist to creating visual representations by proposing a way to construct new visualization designs by blending together a number of existing visual representations, called presets. We embed this novel blending approach in suitable visual interfaces, such as a gridded canvas to be used by the casual user in the style of a palette for mixing colors, or a range of sliders to be used by the expert user in the style of a studio mixer for audio tracks. These can be employed for rapid prototyping of a specific visual representation, as well as to explore the overall design space of visual representations captured by our approach. We showcase our preset-based blending and its interfaces with examples of the design of 2D tree visualizations and product plots.
... Considerations for user interface and interaction for visualization have received great interest in the visualization research community. Many [3,6,7,8] have realized the concept of visualization by examples. He et al. [3] show how volume visualization can be accomplished as an iterative process of viewing and selecting from visualizations generated by computing stochastically in the transfer function space. ...
... Jankun-Kelly et al. [4,5] introduce a spreadsheet-like interface for volume visualization; through this interface, the user can search for ideal visualizations by exploring in the visualization parameter space enumerating different transfer functions, views, etc. Lu and Ebert [7] present a method to generate volume visualizations by emulating example illustrations. Liu et al. [6] called their work "Visualization by Examples" but what they did is essentially to use a spreadsheet interface for composing complex visualizations from simple ones generated automatically. In addition, online visualization sites such as Many Eyes [11] have broadened the scope of visualization by enabling multiple casual users collaborate on setting up and discussing information visualization. ...
... As the complexity of the data, the phenomena to bu captured by the visualization, and the visualization methods to apply continues to grow, advanced knowledge about the application domain and visualization techniques are required to generate satisfactory visualization results. For casual users to make compelling visualizations, it seems only feasible through selecting from suggestive visualization based on image evaluation [3,6]. Consequently, the second kind of interaction is anticipated to receive more attention and popularity. ...
The pervasive concept of cloud computing suggests that visualization, which is both data and computing intensive, is a perfect cloud computing application. This paper presents a sketch of an interface design for an online visualization service. To make such a service attractive to a wider audience, its user interface must be simple and easy to use for both casual and expert users. We envision an interface that supports visualization processes mainly directed by browsing and assessing existing visualizations in terms of images and videos will be very appealing to, in particular, casual users. That is, the aim is to maximize the utilization of the rich visualization data on the web. Without losing generality, we consider volume data visualization applications for our interface design. We also discuss issues in organizing online visualization data, and constructing and managing a rendering cloud.
Finding an appropriate transfer function (TF) for mapping color and opacity values in direct volume rendering (DVR) can be a daunting task. This paper presents a novel approach towards TF generation for DVR, where the traditional low-level color and opacity parameter manipulations are not necessary. The TF generation process is hidden behind a simple and intuitive spherical self-organizing map (SSOM) visualization. The SSOM represents a visual form of the topological relations among the clusters. The user interacts with the SSOM lattice to find interesting regions in the volume. The color and opacity values are generated automatically from the voxel features based on the user׳s perception. We also use harmonic colors to present a visually pleasing result. Due to the independence of SSOM from feature type, our proposed method is flexible in nature and can be integrated with any set of features. The GPU implementation provides real-time volume rendering and fast interaction. Experimental results on several benchmark volume datasets show the effectiveness of our proposed method.
Surface models derived from medical image data often exhibit artefacts, such as noise and staircases, which can be reduced by applying mesh smoothing filters. Usually, an iterative adaption of smoothing parameters to the specific data and continuous re-evaluation of accuracy and curvature is required. Depending on the number of vertices and the filter algorithm, computation time may vary strongly and interfere with an interactive mesh generation procedure. In this paper, we present an approach to improve the handling of mesh smoothing filters. Based on a GPU mesh smoothing implementation of uniform and anisotropic filters, model quality is evaluated in real-time and provided to the user to support the mental optimization of input parameters. This is achieved by means of quality graphs and quality bars. Moreover, this framework is used to find appropriate smoothing parameters automatically and to provide data-specific parameter suggestions. These suggestions are employed to generate a preview gallery with different smoothing suggestions. The preview functionality is additionally used for the inspection of specific artefacts and their possible reduction with different parameter sets.
