Jürgen Döllner

Hasso Plattner Institute · Research Group Computer Graphics Systems

Image-based artistic rendering can synthesize a variety of expressive styles using algorithmic image filtering. In contrast to deep learning-based methods, these heuristics-based filtering techniques can operate on high-resolution images, are interpretable, and can be parameterized according to various design aspects. However, adapting or extending...

Point clouds represent the as-is geometry of indoor and outdoor environments by sets of 3D points. They allow for constructing 3D models of objects, sites, cities, and landscapes and, hence, form the base data for almost any conscious, smart city system and application. For implementing such systems, we need a spatio-temporal data structure that en...

Presentation slides for the corresponding paper. Presented at ICCSA 2022.

The number of publicly accessible software repositories on online platforms is growing rapidly. With more than 128 million public repositories (as of March 2020), GitHub is the world’s largest platform for hosting and managing software projects. Where it used to be necessary to merge various data sources, it is now possible to access a wealth of da...

Various web-based image-editing tools and web-based collaborative tools exist in isolation. Research focusing to bridge the gap between these two domains is sparse. We respond to the above and develop prototype groupware for real-time collaborative editing of raster and vector images in a web browser. To better understand the requirements, we condu...

Fast style transfer methods have recently gained popularity in art-related applications as they make a generalized real-time stylization of images practicable. However, they are mostly limited to one-shot stylizations concerning the interactive adjustment of style elements. In particular, the expressive control over stroke sizes or stroke orientati...

Software projects under version control grow with each commit, accumulating up to hundreds of thousands of commits per repository. Especially for such large projects, the traversal of a repository and data extraction for static source code analysis poses a trade-off between granularity and speed. We showcase the command-line tool pyrepositoryminer...

Signed distance functions computed in discrete form from given RGB-D data as regular voxel grids can represent manifold shapes as the zero crossing of a trivariate function; the corresponding meshes can be derived by the Marching Cubes algorithm. However, 3D models automatically reconstructed in this way often contain irrelevant objects or artifact...

Presentation of paper "Interactive Editing of Voxel-Based Signed Distance Fields" presented at the 30th International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG 2022).

The paper presents a new approach of optimized vectorization to generate stylized artifacts such as drawings with a plotter or cutouts with a laser cutter. For this, we developed a methodology for transformations between raster and vector space. More over, we identify semiotic aspects of Geometry-based Stylization Techniques (GSTs) and the combinat...

Presentation of paper "Design Space of Geometry-based Image Abstraction Techniques with Vectorization Applications" presented at the 30th International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG 2022).

Software projects under version control grow with each commit, accumulating up to hundreds of thousands of commits per repository. Especially for such large projects, the traversal of a repository and data extraction for static source code analysis poses a trade-off between granularity and speed. We showcase the command-line tool pyrepositoryminer...

Software and its dependencies build up a graph where edges connect packages according to their dependencies. In this graph, downstream dependencies are all the nodes that depend on a package of interest. Although gathering and mining such downstream dependencies allow for informed decision-making for a package developer, there is much room for impr...

Image acquisition in low-light conditions suffers from poor quality and significant degradation in visual aesthetics. This affects the visual perception of the acquired image and the performance of various computer vision and image processing algorithms applied after acquisition. Especially for videos, the additional temporal domain makes it more c...

Point clouds or point-based geometry of varying density can nowadays be easily acquired using LiDAR cameras or modern smartphones with LiDAR sensors. We demonstrate how this data can be used directly to create novel artistic digital content using Non-Photorealistic Rendering techniques. We introduce a GPU-based technique for art-directable NPR rend...

In order to detect software risks at an early stage, various software visualization techniques have been developed for monitoring the structure, behaviour, or the underlying development process of software. One of greatest risks for any IT organization consists in an inappropriate distribution of knowledge among its developers, as a projects' succe...

Presentation of research paper "Visualization of Knowledge Distribution across Development Teams using 2.5D Semantic Software Maps".

Presentation of research paper "A Non-Photorealistic Rendering Technique for Art-directed Hatching of 3D Point Clouds".

The paper presents a new approach of optimized vectorization to generate stylized artifacts such as drawings with a plotter or cutouts with a laser cutter. For this, we developed a methodology for transformations between raster and vector space. More over, we identify semiotic aspects of Geometry-based Stylization Techniques (GSTs) and the combinat...

Presentation of research paper FERMIUM: A Framework for Real-time Procedural Point Cloud Animation & Morphing at 26th International Symposium on Vision, Modeling, and Visualization (VMV 2021). Link to talk: https://www.youtube.com/watch?v=mBAiRnbZkAQ

Presentation of research paper "Interactive Multi-level Stroke Control for Neural Style Transfer" at Cyberworlds 2021

We present StyleTune, a mobile app for interactive multi-level control of neural style transfers that facilitates creative adjustments of style elements and enables high output fidelity. In contrast to current mobile neural style transfer apps, StyleTune supports users to adjust both the size and orientation of style elements, such as brushstrokes...

Various web-based image-editing tools and web-based collaborative tools exist in isolation. Research focusing to bridge the gap between these two domains is sparse. We respond to the above and develop prototype groupware for real-time collaborative editing of raster images in a web browser. To better understand the requirements, we conduct a prelim...

Presentation of research paper "COLiER: Collaborative Editing of Raster Images" at Cyberworlds 2021.

This paper presents a framework for generating real-time procedural animations and morphings of 3D point clouds. Point clouds or point-based geometry of varying density can easily be acquired using LiDAR cameras or modern smartphones with LiDAR sensors. This raises the question how this raw data can directly be used in the creative industry to crea...

This work investigates the extent to which animated procedural texture patterns can be used to support the representation of changes in 2.5D treemaps. Changes in height, color, and area of individual nodes can easily be visualized using animated transitions. Especially for changes in the color attribute, plain animated transitions are not able to d...

Personal, long-term investment products, especially ones for retirement savings, require thorough understanding to use them profitably. Even simple savings plans based on exchange-traded funds(ETFs) are subject to many variables and uncertainties to be considered for expected and planned-upon returns. We present aninteractive simulation of an ETF-b...

Software visualization uses metaphors to depict software and software development data that usually has no gestalt. The choice of a metaphor and visual depiction is researched broadly, but deriving a layout based on similarity is still challenging. We present a novel approach to 3D software visualization called Software Galaxy. Our layout is based...

We present StyleTune, a mobile app for interactive style transfer enhancement that enables global and spatial control over stroke elements and can generate high fidelity outputs. The app uses adjustable neural style transfer (NST) networks to enable art-direction of stroke size and orientation in the output image. The implemented approach enables c...

We present MotionViz, an interactive iOS mobile app that enables users to amplify motion and dynamics in videos. MotionViz implements novel augmented reality and expressive rendering techniques in an end-to-end processing pipeline: multi-dimensional video data is captured, analyzed, and processed to render animated graphical elements that help expr...

Taking selfies is a common practice for smartphone users. Simultaneously capturing oneself and the desired background is not a trivial task, because it is often not possible to get a good view of both. Moreover, users often loose attention of their surroundings, thus taking a selfie also showed to lead to serious injuries. To ease the process of ca...

Various web-based image-editing tools and web-based collaborative tools exist in isolation. Research focusing to bridge the gap between these two domains is sparse. We respond to the above and develop a prototype groupware for real-time collaborative editing of raster images in a web browser. To better understand the requirements, we conduct a prel...

We present StyleTune, a mobile app for interactive multi-level control of neural style transfers that facilitates creative adjustments of style elements and enables high output fidelity. In contrast to current mobile neural style transfer apps, StyleTune supports users to adjust both the size and orientation of style elements, such as brushstrokes...

One of the main challenges for the implementation of artificial intelligence (AI) in agriculture includes the low replicability and the corresponding difficulty in systematic data gathering, as no two fields are exactly alike. Therefore, the comparison of several pilot experiments in different fields, weather conditions and farming techniques enhan...

Hilbert and Moore treemaps are based on the same named space-filling curves to lay out tree-structured data for visualization. One main component of them is a partitioning subroutine, whose algorithmic complexity poses problems when scaling to industry-sized datasets. Further, the subroutine allows for different optimization criteria that result in...

This paper presents a service-based approach towards content moderation of digital visual media while browsing web pages. It enables the automatic analysis and classification of possibly offensive content, such as images of violence, nudity, or surgery, and applies common image abstraction techniques at different levels of abstraction to these to l...

Presentation of research paper "Service-based Analysis and Abstraction for Content Moderation of Digital Images" presented at Graphics Interface (GI 2021).

Presentation of research paper "Service-based Processing of Gigapixel Images" presented at 29. International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG 2021).

Presentation of research paper "Interactive Photo Editing on Smartphones via Intrinsic Decomposition" presented at 42nd Annual Conference of the European Association for Computer Graphics (Eurographics’2021).

Presentation of education paper "Teaching Data-driven Video Processing via Crowdsourced Data Collection" presented at 42nd Annual Conference of the European Association for Computer Graphics (Eurographics’2021).

This paper presents the concept and experience of teaching an undergraduate course on data-driven image and video processing. When designing visual effects that make use of Machine Learning (ML) models for image-based analysis or processing, the availability of training data typically represents a key limitation when it comes to feasibility and eff...

This paper describes an approach for using the Unity game engine for image processing by integrating a custom GPU-based image processor. It describes different application levels and integration approaches for extending the Unity game engine. It further documents the respective software components and implementation details required, and demonstrat...

This paper describes an approach for using the Unity game engine for image processing by integrating a custom GPU-based image processor. It describes different application levels and integration approaches for extending the Unity game engine. It further documents the respective software components and implementation details required, and demonstrat...

Presentation of the research paper "Integration of Image Processing Techniques into the Unity Game Engine" at the 1st International Conference on Image Processing and Vision Engineering (IMPROVE 2021).

Intrinsic decomposition refers to the problem of estimating scene characteristics, such as albedo and shading, when one view or multiple views of a scene are provided. The inverse problem setting, where multiple unknowns are solved given a single known pixel-value, is highly under-constrained. When provided with correlating image and depth data, in...

Software visualization techniques provide effective means for program comprehension tasks as they allow developers to interactively explore large code bases. A frequently encountered task during software development is the detection of source code files of similar semantic. To assist this task we present Software Forest, a novel 2.5D software visua...

With the ongoing improvement of digital cameras and smartphones, more and more people can acquire high-resolution digital images. Due to their size and high performance requirements, such Gigapixel Images (GPIs) areoften challenging to process and explore compared to conventional low resolution images. To address this problem,this paper presents a...

With the ongoing improvement of digital cameras and smartphones, more and more people can acquire high- resolution digital images. Due to their size and high performance requirements, such Gigapixel Images (GPIs) are often challenging to process and explore compared to conventional low resolution images. To address this problem, this paper presents...

Treemaps are a commonly used tool for the visual display and communication of tree-structured, multi-variate data. In order to confidently know when and how treemaps can best be applied, the research community uses usability studies and controlled experiments to "understand the potential and limitations of our tools" (Plaisant, 2004). To support th...

This paper provides an overview of published treemap layout algorithms from 1991 to 2019 that were used for information visualization and computational geometry. First, a terminology is outlined for the precise communication of tree-structured data and layouting processes. Second, an overview and classification of layout algorithms is presented and...

In this paper, we present a 2.5D visualization technique based on the dust & magnet metaphor, which generally allows for interactively exploring and analyzing large multivariate data sets. In addition to position and color, we introduce height as additional visual variable for particles to encode extra data attributes in the 2.5D visualization, thu...

A truthful and unbiased display of data using information visualization requires detecting and communicating uncertainty. Uncertainty is often inherent in data or is introduced by data processing and visualization (e.g., visual display of accumulated data) but frequently not accounted for. This paper discusses the suitability of advanced visual var...

This paper presents a rendering framework for the visualization of massive point datasets in the web. It includes highly interactive point rendering, cluster visualization, basic interaction methods, and importance-based labeling, while being available for both mobile and desktop browsers. The rendering style is customizable, as shown in figure 1....