BENJAMIN KAHL

The Max Planck Institute for Human Development frequently conducts psychological experiments in VR. However, due to wildly varying experiment specifications, there is a distinct lack of tools and frameworks to aid their development.
ARC-VR is a Unity3D framework that aims to ameliorate the development process by providing any and all basic VR features, such as movement, physics-interaction and UI. Thus ensuring the development process doesn't get congested at an early stage with the implementation of redundant, basic VR functionalities.

As a semi-followup to our ProducerScroungers in Minecraft study, CoinScrounge seeks to model the cognitive processes governing dynamically-interacting individuals in human collectives under realistic conditions. For this purpose, I built a Unity-based 3D multiplayer game where four players use a metal detector to search a field of grass for coins, under varying conditions. The end result was one of the most complex and complete multiplayer-projects I've worked on, including a large amount of custom-written netcode. The final manuscript has been accepted for publication in nature communications.

Why anyone would think that creating a Lord of The Rings themed game by modifying a WW2 strategy game is a good idea seems puzzling. Yet, here we are.
This Hearts of Iron 4 mod started off as a small, 'play-with-friends', meme-project but unexpectedly exploded in popularity on the steam workshop, having gained exposure from some of the games most popular content creators.
With its distinctly satirical and humorous ways of describing events as well as enabling otherwise unthinkable 'alternate history' paths, this mod has remained highly and has garnered an active and thriving online community.

The Runners Study is in many ways similar to the 'Statues' or 'Red Light, Green Light' games. Four animated monsters advance on the participant at different speeds. By using eye-tracking, the participant can stop one of these monsters by looking at it. The monsters have different colors and patterns, which correlate with a monster's speed. The purpose of the study is to investigate whether embedding the learning process in performing instrumental actions, where all the relationships they need to learn about are always visible to them, can help with the learning of cue-outcome relationships in young children.

Wave field synthesis (WFS) is an audio rendering technique that creates virtual acoustic environments by simulating sound waves. Loudspeaker arrays synthesize artificial wavefronts that seem to originate from a given start-point by super-imposing a large set of individual, elementary sound-waves. As an initial stepping-stone, I sought to combine WFS into a simple VR-based experiment that measures how accurately participants perceive the origin-points of artificial wavefronts. Further points of interest include (but are not limited to) which factors affect localization-accuracy, which advantages and limitations WFS systems have over their more accessible counterparts, and which type of studies would benefit most from it’s integration.

RTRad is an enhanced implementation of progressive refinement radiosity using Nvidia's RTX technology to accelerate visibility calculations.
The project is built on Falcor 4.4 and contains a highly configureable pipeline. GI lightmaps can be generated in a variety of different ways and individual data components can easily be visualized. Custom scenes and models can be defined and loaded into the rendering environment using the .pyscene format.
The development took place as part of a Masters's thesis at the Freie Universität Berlin.

Building systems capable of replicating global illumination models with interactive frame-rates has long been one of the toughest conundrums facing computer graphics researchers. Voxel Cone Tracing, as proposed by Cyril Crassin et al. in 2011, makes use of mipmapped 3D textures containing a voxelized representation of an environments direct light component to trace diffuse, specular and occlusion cones in linear time to extrapolate a surface fragments indirect light emitted towards a given photo-receptor.
Seemingly providing a well-disposed balance between performance and physical fidelity, this thesis examines the algorithms theoretical side on the basis of the rendering equation as well as its practical side in the context of a self-implemented, OpenGL-based variant.

A key question individuals face in any social learning environment is when to innovate alone and when to imitate others. The 'producer-scrounger' model is a mould in psychology that outlines social foraging tactics often observed among animals on their search for food.
With this minecraft-based experiment we analyze how the model manifests itself among the participants and shine new light on how groups collectively adapt to the fluctuating demands of the environment through specialization and selective imitation, rather than homogeneity and indiscriminate copying of others.
Our employed POV-rendering tools facilitate unprecedented access to a combined analysis of spatial trajectories and visual field data.

As a follow-up study on both CoinScrounge and the ProducerScroungers Minecraft study, we sought to reduce and simplify the concept by narrowing down options and movement without removing the continous timescale. The Fishing Dilemma gives the player only one possible input option: to switch ponds. Despite the simple premise, the implementation of this experiment was valuable and enriching for my progression as a software developer. Reason being that I decided to implement the entire netcode from scratch. The experiment is effectively built on a network-synchronized C# dictionary, letting the clients interpret it's contents and display the current gamestate to the participant.

Building a personal portfolio-website has long been on my todo-list. Having finally gotten around to it, I designed and implemented a python-based framework that allows to easily and modularly insert content semi-dynamically without having to write direct HTML code.
Additionally, in a long process of conceptualization, I created a modern graphic design that attempts to capture my field of expertise (computer graphics) and display any desired content seamlessly whilst sticking to the underlying theme.

A convex partition of a pointset consists of a planar subdivision of its convex hull so that all faces are empty and convex. Finding a partition with the minimum amount of edges (or faces), is still a problem of unknown complexity.
As part of the CG:SHOP 2020 competition we devised a set of four different algorithms to compute various convex partitions for differently arranged pointsets.
Unlike most of our competitors, our methods consisted purely of discrete, algorithmic solutions. The way in which they compared yielded some interesting observations.

AutoNOMOS-Model Robots are developed at the Free University of Berlin and are employed internationally by various universities and institutes for research- and teaching-purposes. To enhance accessibility to these, we developed a Unity3D simulator which enables a user to connect a ROS environment to a virtual robot.

The nonprofit organization Animal Charity Evaluators (ACE) is optimistic that the coming years will see an increase in high-quality targeted research into animal welfare, so now more than ever there is value in collecting, pruning, and organizing the research such that other researchers and implementing parties – companies, foundations, nonprofits, and government offices among them – can quickly gain an overview of it.
The goal of the ACE Research Library project is to provide ACE with an interface that aids the staff in entering new articles and papers and to provide the visitors of ACE’s website with powerful search and drilldown mechanisms.
The research library has been employed by ACE since 2016 and, thanks to being agnostic of the user, can be used by anyone with similar requirements on their data organization.

With the rising popularity of standalone, mobile VR headsets, cognitive studies are more difficult to run, since the experimenter cannot control or see the view of the participant. RCAS (Remote-Control-And-Streaming) is a Unity framework intended to enable remote control of an application running on a remote mobile VR headset in addition to live-streaming the VR view. Developed as a freelance project for the Max Planck Institute for Human Cognitive and Brain Sciences, it is lightweight and allows for an image to be streamed from a mobile VR headset to a phone or other device in addition to allowing the experimented to control the experiment through RCE as well as retrieved any data recorded on the headset.