Daniel Limberger

Image stylization by interactive oil paint filtering

This paper presents an interactive system for transforming images into an oil paint look. The system comprises two major stages. First, it derives dominant colors from an input image for feature-aware recolorization and quantization to conform with a global color palette. Afterwards, it employs non-linear filtering based on the smoothed structure adapted to the main feature contours of the quantized image to synthesize a paint texture in real-time. Our filtering approach leads to homogeneous outputs in the color domain and enables creative control over the visual output, such as color adjustments and per-pixel parametrizations by means of interactive painting. To this end, our system introduces a generalized brush-based painting interface that operates within parameter spaces to locally adjust the level of abstraction of the filtering effects. Several results demonstrate the various applications of our filtering approach to different genres of photography. Graphical abstractDisplay Omitted HighlightsAn approach for image stylization with an oil paint look by means of image filtering is proposed.A method for image quantization is introduced that is based on the dominant colors derived from local image regions.A real-time paint texture synthesis is proposed based on the smoothed image structure.An interactive painting system is provided that supports brush-based per-pixel parametrizations of local image filters.

Reducing Visual Complexity in Software Maps using Importance-based Aggregation of Nodes.

Depicting massive software system data using treemaps can result in visual clutter and increased cognitive load. This paper introduces an adaptive level-of-detail (LoD) technique that uses scoring for interactive aggregation on a per-node basis. The scoring approximates importance by degree-of-interest measures as well as screen and user-interaction scores. The technique adheres to established aggregation guidelines and was evaluated by means of two user studies. The first investigates task completion time in visual search. The second evaluates the readability of the presented nesting level contouring for aggregates. With the adaptive LoD technique software maps allow for multi-resolution depictions of software system information while facilitating annotation and efficient identification of important nodes.

Real-time rendering of high-quality effects using multi-frame sampling

In a rendering environment of comparatively sparse interaction, e.g., digital production tools, image synthesis and its quality do not have to be constrained to single frames. This work analyzes strategies for highly economically rendering of state-of-the-art rendering effects using progressive multi-frame sampling in real-time. By distributing and accumulating samples of sampling-based rendering techniques (e.g., anti-aliasing, order-independent transparency, physically-based depth-of-field and shadowing, ambient occlusion, reflections) over multiple frames, images of very high quality can be synthesized with unequaled resource-efficiency.

Evaluation of Sketchiness as a Visual Variable for 2.5D Treemaps

Treemaps serve as generic, effective tools to display, explore, and analyze multi-variate tree data in a scalable, interactive, and consistent way. In this paper, we discuss and evaluate sketchiness as visual variable of 2.5D treemaps. Sketchy rendering techniques allow us to map data, e.g., about uncertainty, imprecision, or vagueness, independently from mappings to other visual variables such as size, color, and height. To this end, we present a design space for sketchy rendering for 2.5D treemaps and corresponding implementation of a real-time sketchy rendering technique. The results of three user studies carried out indicate that sketchiness is a promising candidate for an independent visual variable for 2.5D treemaps, in particular to map ordinal data with a small range such as data that qualifies map items, it shows no strong interference with other visual variables such as color and height due to the regular gestalt of blocks and, hence, allows us to extend the expressiveness of 2.5D treemaps.

Interactive, Height-Based Filtering in 2.5D Treemaps

The 2.5D treemap facilitates interactive exploration of multivariate data. It includes height as a visual variable for additional information display and enables exploration of correlations within mapped attributes. In this paper techniques for the visual display of a height reference for interactive modification from within the visualization are introduced. Results of a preliminary user study are presented and potential benefits for improved performance, i.e., precision and speed, of identification, comparison, filtering, and selection tasks are discussed.

Progressive high-quality rendering for interactive information cartography using WebGL

Information cartography services provided via web-based clients using real-time rendering do not always necessitate a continuous stream of updates in the visual display. This paper shows how progressive rendering by means of multi-frame sampling and frame accumulation can introduce high-quality visual effects using robust and straightforward implementations. For it, (1) a suitable rendering loop is described, (2) WebGL limitations are discussed, and (3) an adaption of THREE.js featuring progressive anti-aliasing, screen-space ambient occlusion, and depth of field is detailed. Furthermore, sampling strategies are discussed and rendering performance is evaluated, emphasizing the low per-frame costs of this approach.

Dynamic 2.5D treemaps using declarative 3D on the web

The 2.5D treemap represents a general purpose visualization technique to map multi-variate hierarchical data in a scalable, interactive, and consistent way used in a number of application fields. In this paper, we explore the capabilities of Declarative 3D for the web-based implementation of 2.5D treemap clients. Particularly, we investigate how X3DOM and XML3D can be used to implement clients with equivalent features that interactively display 2.5D treemaps with dynamic mapping of attributes. We also show a first step towards a glTF-based implementation. These approaches are benchmarked focusing on their interaction capabilities with respect to rendering and speed of dynamic data mapping. We discuss the results for our representative example of a complex 3D interactive visualization technique and summerize recommendations for improvements towards operational web clients.