Jürgen Döllner

Universität Potsdam · Chair for Computer Graphics

Video Moment Retrieval (VMR) is a challenging task at the intersection of vision and language, with the goal to retrieve relevant moments from videos corresponding to natural language queries. State-of-the-art approaches for VMR often rely on large amounts of training data including frame-level saliency annotations, weakly supervised pre-training o...

As machine learning models are becoming more widespread and see use in high-stake decisions, the explainability of these decisions is getting more relevant. One approach for explainability are counterfactual explanations, which are defined as changes to a data point such that it appears as a different class. Their close connection to the original d...

Text synthesis tools are becoming increasingly popular and better at mimicking human language. In trust-sensitive decisions, such as plagiarism and fraud detection, identifying AI-generated texts poses larger difficulties: decisions need to be made explainable to ensure trust and accountability. To support users in identifying AI-generated texts, w...

Topic models are a class of unsupervised learning algorithms for detecting the semantic structure within a text corpus. Together with a subsequent dimensionality reduction algorithm, topic models can be used for deriving spatializations for text corpora as two-dimensional scatter plots, reflecting semantic similarity between the documents and suppo...

This paper introduces an art-directable stroke-based rendering technique for transforming photos into painterly renditions on mobile devices. Unlike previous approaches that rely on time-consuming iterative computations and explicit brush-stroke geometry, our method offers an interactive image-based implementation tailored to the capabilities of mo...

Presentation of the research paper "Controlling Geometric Abstraction and Texture for Artistic Images" at the 22th International Conference on Cyberworlds (CW2023) in Sousse, Tunisia.

Building Information Modelling (BIM) is becoming increasingly prevalent in infrastructure asset management, as it facilitates current management practices. This includes the construction of BIM models for roads, rails, bridges, tunnels etc. Bridges are particularly challenging to digitalize due to their complex geometry. The manual construction of...

Digital twins that serve as virtual representations of real-world objects and structures, are used in various applications for urban environments. Challenges for creating and maintaining digital twins involve data acquisition, fusion of heterogeneous data types, AI-based data analysis, and the integration into existing applications and workflows. I...

We present a novel method for the interactive control of geometric abstraction and texture in artistic images. Previous example-based stylization methods often entangle shape, texture, and color, while generative methods for image synthesis generally either make assumptions about the input image, such as only allowing faces or do not offer precise...

Readily available software analytics tools are often operated as external services, where measured software analysis data is kept internal , and no external use of the data is available. We propose an approach for embedded visual software analytics on the GitHub platform by leaveraging GitHub Actions and the GitHub API. The proposed approach collec...

Ray tracing remains of interest to Computer Graphics community with its elegant framing of how light interacts with objects, being able to easily support multiple light sources, and simple framework of merging synthetic and real cameras. Recent trends to provide implementations at the chip-level means raytracing’s constant quest of realism would pr...

This paper presents a framework and mobile video editing app for interactive artistic augmentation of human motion in videos. While creating motion effects with industry-standard software is time-intensive and requires expertise, and popular video effect apps have limited customization options, our approach enables a multitude of art-directable, hi...

Presentation of the research paper "Interactive Control over Temporal Consistency while Stylizing Video Streams" at the 34th Eurographics Symposium on Rendering (EGSR 2023) in Delft, Netherlands.

This contribution presents the use of a newly developed approach for the generation and modelling of spatially referenced, multidimensional virtual city models from remote sensing data, exemplified by the case of East Jerusalem. The focus is on the effective application of the entire process from data acquisition, pre-processing and management to s...

Image stylization has seen significant advancement and widespread interest over the years, leading to the development of a multitude of techniques. Extending these stylization techniques, such as Neural Style Tranfser (NST), to videos is often achieved by applying them on a per-frame basis. However, per-frame stylization usually lacks temporal cons...

In urban environments, roadside vegetation provides important ecosystem services. Reliable and up-to-date information on urban vegetation is therefore needed as a basis for sustainable urban design and regular tasks such as vegetation maintenance. Mobile laser scanning (MLS), i. e., the use of vehicle-mounted laser scanners, offers strong potential...

The Hilbert and Moore treemap layout algorithms are based on the space-filling Hilbert and Moore curves, respectively, to map tree-structured datasets to a 2D treemap layout. Considering multiple snapshots of a time-variant dataset, one of the design goals for Hilbert and Moore treemaps is layout stability, i.e., low changes in the layout for low c...

The Hilbert and Moore treemap layout algorithms are based on the space-filling Hilbert and Moore curves, respectively, to map tree-structured datasets to a 2D treemap layout. Considering multiple snapshots of a time-variant dataset, one of the design goals for Hilbert and Moore treemaps is layout stability, i.e., low changes in the layout for low c...

Quali-quantitative methods provide ways for interrogating Convolutional Neural Networks (CNN). For it, we propose a dashboard using a quali-quantitative method based on quantitative metrics and saliency maps. By those means, a user can discover patterns during the training of a CNN. With this, they can adapt the training hyperparameters of the mode...

LiDAR scanning technology is an established method for capturing landscapes, buildings, or roads in order to create a so-called spatial digital twin of the reality, stored as a large collection of 3D coordinates called 3D point cloud. This spatial data offers high density and precision at the cost of hard to extract shape or object information. One...

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 computer vision and image processing algorithms applied after acquisition. Especially for videos, the additional temporal domain makes it more challengi...

Presentation of the research contribution "ALIVE: Adaptive Chromaticity for Interactive Low-light Image and Video Enhancement" at the 31. International Conference on Computer Graphics, Visualization and Computer Vision (WSCG 2023).

Presentation of the research contribution "A Framework for Art directed Augmentation of Human Motion in Videos on Mobile Devices" at the 31. International Conference on Computer Graphics, Visualization and Computer Vision (WSCG 2023).

This paper presents a framework and mobile video editing app for interactive artistic augmentation of human motion in videos. While creating motion effects with industry-standard software is time-intensive and requires expertise, and popular video effect apps have limited customization options, our approach enables a multitude of art-directable, hi...

Using software metrics as a method of quantification of software, various approaches were proposed for locating defect-prone source code units within software projects. Most of these approaches rely on supervised learning algorithms, which require labeled data for adjusting their parameters during the learning phase. Usually, such labeled training...

Offers to buy and sell cryptocurrencies on exchanges are collected in an order book as pairs of amount and price provided with a timestamp. Contrary to tick data, which only reflects the last transaction price on an exchange, the order book reflects the market's actual price information and the available volume. Until now, no system has been presen...

Most cryptocurrencies are bought and sold on centralized exchanges that manage supply and demand via an order book. Besides trading fees, the high liquidity of a market is the most relevant reason for choosing one exchange over the other. However, as the different liquidity measures rely on the order book, external events that cause people to sell...

Trading for a currency pair on centralized crypto exchanges is organized via an order book, which collects all open buy and sell orders at any given time and thus forms the basis for price formation. Usually, the exchanges provide basic visualizations, which show the accumulated buy and sell volume in an animated 2D representation. However, this vi...

Real estate is the largest asset class and is equally popular with professional and retail investors. However, this asset class has the disadvantage that it is very illiquid, and investments have a high entry barrier in terms of equity. The adoption of the Electronic Securities Act in 2021 by the German Bundestag has created the legal framework for...

Continuous Integration and Continuous Delivery are best practices used in the context of DevOps. By using automated pipelines for building and testing small software changes, possible risks are intended to be detected early. Those pipelines continuously generate log events that are collected in semi-structured log files. In practice, these log fil...

During the software development process, occurring problems are collected and managed as bug reports using bug tracking systems. Usually, a bug report is specified by a title, a more detailed description, and additional categorical information, e.g., the affected component or the reporter. It is the task of the triage owner to assign open bug repor...

More and more people are using images and videos as a communication tool. Often, such visual media is edited or stylized using software applications to become more visually attractive. The data that is produced by the editing process contains useful information on how users interact with the software and data yielding respective results. In this co...

Presentation of research paper "A Service-based Preset Recommendation System for Image Stylization Applications" at the "7th International Conference on Human Computer Interaction Theory and Applications (HUCAPP 2023)"

Self-Supervised Network Projections (SSNP) are dimensionality reduction algorithms that produce low-dimensional layouts from high-dimensional data. By combining an autoencoder architecture with neighborhood information from a clustering algorithm, SSNP intend to learn an embedding that generates visually separated clusters. In this work, we extend...

For various program comprehension tasks, software visualization techniques can be beneficial by displaying aspects related to the behavior, structure, or evolution of software. In many cases, the question is related to the semantics of the source code files, e.g., the localization of files that implement specific features or the detection of files...

With the advent of Neural Style Transfer (NST), stylizing an image has become quite popular. A convenient way for extending stylization techniques to videos is by applying them on a per-frame basis. However, such per-frame application usually lacks temporal-consistency expressed by undesirable flickering artifacts. Most of the existing approaches f...

For decades, Image-based Artistic Rendering (IB-AR) has been successfully employed to simulate the appeal of traditional artistic styles for enhanced visual communication. Recently, 3D photography has emerged as a new medium that provides an immersive dimension compared to 2D photos. The possibility to change the viewpoint, depicting parallax effec...

Presentation of paper "Trios - A Framework for Interactive 3D Photo Stylization on Mobile Devices" presented at the International Conference on Graphics and Interaction (IGCI 2022) in Aveiro, Portugal.

3D scatter plots depicting massive data suffer from occlusion, which makes it difficult to get an overview and perceive structure. This paper presents a technique that facilitates the comprehension of heavily occluded 3D scatter plots. Data points are projected to axial planes, creating x-ray-like 2D views that support the user in analyzing the dat...

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...

Presentation of research paper "CodeCV: Mining Expertise of GitHub Users from Coding Activities" at the 22nd IEEE International Working Conference on Source Code Analysis and Manipulation in Limassol, Cyprus.

The number of software projects developed collaboratively on social coding platforms is steadily increasing. One of the motivations for developers to participate in open-source software development is to make their development activities easier accessible to potential employers, e.g., in the form of a resume for their interests and skills. However,...

Treemaps depict tree-structured data while maintaining flexibility in mapping data to different visual variables. This work explores how changes in data mapped to color can be represented with rectangular 2.5D treemaps using procedural texture patterns. The patterns are designed to function for both static images and interactive visualizations with...

We present an approach for real-time non-photorealistic rendering (NPR) of 3D point clouds that provides a general-purpose component for their cartographic visualization. For a given 3D point cloud, per-point attributes are derived in the preprocessing phase, e.g., for geometric, semantic, and instance information. The point cloud thus attributed i...

Software maps provide a general-purpose interactive user interface and information display in software analytics. This paper classifies software maps as a containment-based treemap embedded into a 3D attribute space and introduces respective terminology. It provides a comprehensive overview of advanced visual metaphors and techniques, each suitable...

Visualization of annotation recording using a digital indoor model (e.g., point clouds, 3D models, 2D floorplans) allows stakeholders to see exactly how, e.g., furniture items or machinery have been moved from one location in a building to another. The recording of such actions is vital for record keeping and future decision-making within the realm...

Based on the assumption that semantic relatedness between documents is reflected in the distribution of the vocabulary, topic models are a widely used class of techniques for text analysis tasks. The application of topic models results in concepts, the so-called topics, and a high-dimensional description of the documents. For visualization tasks, t...

Presentation of research paper "A Benchmark for the Use of Topic Models for Text Visualization Tasks" at the 15th International Symposium on Visual Information Communication and Interaction in Chur, Switzerland.

3D photography has emerged as a medium that provides an immersive dimension to 2D photos. We present Trios, an interactive mobile app that combines the vividness of image-based artistic rendering with 3D photos by implementing an end-to-end pipeline for their generation and stylization. Trios uses Apple’s accelerated image-processing APIs and dedic...

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...

Presentation of the research paper "Efficient GitHub Crawling using the GraphQL API" at the 22nd International Conference on Computational Science and Its Applications in Malaga, Spain.

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...

Presentation for the 2022 EuroCarto contribution on "Non-Photorealistic Rendering of 3D Point Clouds for Cartographic Visualization".

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...