Virtual Reality and Physically-Based Simulation WS 17/18

Virtual Reality (VR) is a research area at the intersection of computer graphics, physically-based simulation, and 3D human-computer interaction (HCI). VR and 3D realtime computer games share a lot of algorithmic challenges: novel interaction technologies and interaction metaphors in virtual environments (in particular, intuitive and direct metaphors), immersion and presence, and real-time rendering. Another important topic is physically-based simulation in real-time, which tries to simulate real-world phenomena such as fire, cloth, the behavior of rigid objects when colliding with each other, fluids, or objects made of deformable material.

Over the past two decades, VR has established itself as an important tool in several industries, such as manufacturing (e.g., automotive, airspace, ship building), architecture, and pharmaceutical industries. During the past few years, we have been witnessing the second "wave" of VR, this time in the consumer, in particular, entertainment markets.

In this course, we will first look at the fundamental methods, and then go on to more advanced algorithms that are needed to build complex and full-fledged VR systems or real-time computer games. Example topics are 3D interaction, physically-based behavior of objects, acoustic rendering, haptics, and collision detection.

The assignments will be mostly practical ones, based on the cross-platform game engine Unreal. Participants will start developing with "visual programming", and later use C++ to solve the assignments.
You are encouraged to work on assignments in small teams.

Some of the topics to be covered (tentatively):

  1. Introduction, basic notions of VR, a few applications
  2. VR technologies: displays, tracking, input devices, software design
  3. Stereo rendering
  4. Error correction: tracking correction, filtering
  5. Techniques for real-time rendering
  6. Fundamental immersive interaction techniques: gesture recognition, navigation, selection, grasping, menues in 3D
  7. Complex immersive interaction techniques: world-in-miniature, action-at-a-distance, magic lens, etc.
  8. Particle systems
  9. Spring-mass systems
  10. Force feedback: rendering forces
  11. Collision detection
  12. Acoustic rendering

Note: this list is just tentative and subject to change during the semester.


Exams will take place on Feb 28 &emdash; please go to Studip to sign up for a slot.


The following table will, eventually, contain all the topics that were covered in this class, the accompanying slides, exercise sheets, and frameworks for solving the programming exeercises. (This table will be filled week by week.)

Week Topics Slides Exercise
1. Orga stuff
Introduction: definitions, applications, immersion, fidelity, presence,
PDF0 PDF1 Assignment 1 IGR CSV template
2. Intro 2: body ownership illusion, history, Milgram's continuum
Scenegraphs: immediate / retained mode, semantics of nodes and edges, special issues with light sources,
3. Scenegraphs 2: shared geometry (instancing), thread-safe scenegraphs, distributed rendering, fields & routes concept, types of nodes, the Phong model for specification of the material, indexed face set, OBJ file format, FBX file format, PDF Assignment 2
4. Scenegraphs 3: hierarchical transformations, routes & events, behavior graph, KV pool.
Displays and stereo rendering 1: depth cues, human visual system and stereopsis, horopter and fusion area, multiplexing techniques for stereo images (polarization, shuttering, color filtering), immersive didplays / immersive projection technologies
5. Stereo rendering 2: correct stereo projection, hypo- and hyper-stereo, issues with stereo rendering (depth aliasing, convergence-focus incongruity, incorrect viewpoint, stereo violation, depth blur, too much parallax), model of user's head, coherent virtual workspace, multiplexing for multiple users, automultiscopic display, pre-distortion for HMDs, PDF Assignment 3 Laggy Jump Evaluation
6. Dies Academicus
7. Real-time rendering 1: simulator sickness, latency and its sources, view-independent rendering, prioritized rendering, level-of-detail techniques, static/dynamic/psychophysiological LOD selection, predictive LOD selection PDF Assignment 4
8. Real-time rendering 2: dynamic LODs, progressive meshes, view-dependent LODs, portal culling, state sorting using online sorting buffer algorithms, stereoscopic image warping, latencies with conventional rendering, reducing latency using time warping
Input Devices: degrees of freedom, multimodality, virtual trackball, directness continuum, isotonic vs isometric, tracking, data gloves, locomotion devices.
9. Interaction techniques 1: Universal Interaction Tasks, design of user interfaces, gesture recognition, the navigation task (wayfinding & locomotion), taxonomies as a design tool, abstract representation of the user for navigation, navigation metaphors (point-and-fly, scene-in-hand, two-handed, hands-free, walking in place, et al.), 3D navidget, user models (power law of practice, Hick's law, Fitts's law), PDF
10. Interaction techniques 2: iso-/non-isomorphic techniques, control-display ratio, go-go technique, task decomposition of selection task, selection techniques: ray-based & cone-based techniques, flexible pointer, friction surface (bent ray), eye-hand mismatch, cone-based technique with ranking, balloon selection, object manipulation (grasping and moving), taxonomy of grasping, Natural User Interaction, principles for interaction design: action-at-a-distance, image plane interaction, proprioceptive interaction, world-in-miniature, magic lenses, redirected walking and related techniques, PDF Assignment 5
11. Particle systems: Newton's Laws, dynamics/kinematics, Euler integration, phase space, definition of particle systems, forces from physical effects, non-physical effects, collision handling, rendering of particle systems, alpha blending, flames & fire, procedural modeling of plants, the concept of streaming architectures PDF
12. Mass-spring systems: definition, single spring-damper element, explicit Euler integration, instability and error accumulation with explicit Euler integration, Runge-Kutta, Verlet integration, constraints, implicit integration, tangent stiffness matrix, comparison to explicit integration, mesh creation for volumetric objects, PDF Assignment 6 Mass-spring framework
13. Haptics: applications, devices, the haptic loop, human haptic sense and human factors, simulation factors, haptic textures, buzzing, intermediate representations, software architecture, impedance and admittance, the surface contact point method, voxmap-pointshell method, friction in one contact point, PDF
14. Collision detection: motivation, definitions, collision detection pipeline, broad/narrow phase, plane-sweep technique, separating planes algorithm (for convex objects), hierarchical coll.det., bounding volume hierarchies, types of BV's, separating axis lemma for convex polyhedra, inner sphere trees, sphere packings, proximity computation using ISTs, penalty forces using ISTs.


Warning: these text books can only give you a general introduction to the field of VR! Most of the topics taught in class will not be covered by any of these text books directly -- in fact, AFAIK there are no text books that cover these topics. Therefore, I recommend to attend class.

If you are thinking of buying some of these books, then I suggest to consider buying a used copy of them -- very often, you can find them at a fraction of the price of a new copy. The following are two very good internet sites for finding inexpensive used copies of books: Abebooks and BookButler.


In order to acquire the "Schein", you will have to do a number of assignments. These will be mostly small practical programming assignments (based on a freely available VR system).

Help and documentation on the Unreal Engine:

Online Literature and Resources on the Internet

Literature and Resources on X3D/VRML
Since X3D/VRML is no longer the platform for the practical exercises in this course, I have demoted the links to X3D/VRML to this place.

Readings That Have Nothing to do With VR, but are Still Highly Recomended

Gabriel Zachmann
Last modified: Wed Jan 31 14:24:46 CET 2018