Virtual Reality and Physically-Based Simulation, WS 24/25


Virtual Reality (VR) is a research area at the intersection of computer graphics, physically-based simulation, and 3D human-computer interaction (HCI). novel interaction technologies and interaction metaphors VR and 3D realtime computer games share a lot of algorithmic challenges: 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, in the 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. (See below for an installation guide.) 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, several example applications
  2. VR technologies: displays, tracking, input devices, scene graphs, game engines
  3. The human visual system and Stereo rendering
  4. Techniques for real-time rendering
  5. Fundamental immersive interaction techniques: fundamentals and principles, 3D navigation, user models, 3D selection, redirected walking, system control
  6. Complex immersive interaction techniques: world-in-miniature, action-at-a-distance, magic lens, etc.
  7. Particle systems
  8. Spring-mass systems
  9. Haptics and force feedback
  10. Collision detection
  11. Acoustic rendering

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

For Students from Other Institutions

If you are from an educational institution other than University of Bremen, you can still join my course, if you fill out this form and apply as a guest student. When successfull, you will get an account with the Universtity of Bremen, which will allow you to access StudIP. There, you can sign up for the course.

News

You can use this Discord channel to discuss or coordinate amongst yourself. Occasionally, the tutors will answer questions, too, should you have any for them.

Slides, Assignments, Recordings

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 exercises. This table will be filled week by week.
Occasionally, I will post short videos here, too, which I would like to ask you to watch in preparation for the respective week's lecture.
Videos encoded with H.265/HEVC (mp4 container) play fine in Safari, encodings with VP9 (webm container) play in all other browsers. (H265 only appears to play under Windows in Edge, but it is buggy.) Otherwise, just download them, then play them with VLC.

Week Topics Slides Video Assignments Frameworks
1. Orga stuff
Introduction and Psychological aspects of VR: classification of vritual environments (VEs), definiton of virtualization, immersion, benefits of immersion, fidelity, presence, components and types of presence, potential explanation and factors for the occurence of presence, measuring presence, behavior change (virtual coral reef application), avatars and virtual body ownership, measuring IVBO and importance of realism, cybersickness, technical causes and neurophysiological hypotheses, mitigation, measuring cybersickness, Milgram's continuum, augmented reality (video) 		PDF0 PDF1 H256 VP9
H256, VP9 		Intro to UE5
Assignment 1
Submission Remarks
2. Scenegraphs: immediate / retained mode, semantics of nodes and edges, inheritance,
Lab meeting with demos
Holiday (Reformationstag) 		H256 VP9
3. Scenegraphs: special issues with light sources, shared geometry (instancing), thread-safe scenegraphs, distributed scenegraphs, fields & routes concept, types of nodes, nodes and fields (entities and components), the Phong model for specification of the material, superficial intro to BRDF's, indexed face set, OBJ file format, FBX file format, specification of transformations, hierarchical transformations, behavior graph, data flow paradigm, execution model & event cascades,
Display technologies and stereo rendering: depth cues, stereopsis in the human visual system, horopter and fusion area, VR displays / immersive displays / immersive projection technologies, multiplexing techniques for stereo images (polarization, shuttering, color filtering), automultiscopic display, correct stereo projection, hypo- and hyper-stereo, optimization of stereo rendering performance, 		PDF PDF H256 VP9
4. Display technologies and stereo rendering: model of user's head, issues with stereo rendering (depth aliasing, convergence-focus conflict, incorrect viewpoints, stereo violation, blur divergence, too much parallax), coherent virtual workspaces,
Real-time rendering: latency and its sources, view-independent rendering, prioritized rendering, level-of-detail techniques, static/adaptive/psychophysiological LOD selection,
Lab meeting 		PDF PDF Assignment 2 Framework ex. 3
5. Real-time rendering: predictive LOD selection, progressive meshes, view-dependent LODs, Foveated rendering, 3D warping.
Principles of input devices: self-study Interaction techniques: Universal Interaction Tasks, approaches to design of user interfaces, 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,
(Fire alarm) 		PDF PDF1 PDF2 H256 VP9 Assignment 3 Laggy Jump LOD Meshes
6. Interaction techniques: other navigation techniques (hands-free, walking in place, et al.), 3D navidget,
user models: power law of practice, Hick's law, Fitts's law;
3D selection techniques, iso-/non-isomorphic techniques, control-display ratio, go-go technique, task decomposition of selection task, ray-based & cone-based selection techniques, 		PDF
7. Interaction techniques: flexible pointer, friction surface (bent ray), eye-hand mismatch, cone-based technique with ranking, bubble cursor, depth ray, balloon selection, selection by progressive refinement: SQUAD, Disambiguation Canvas, Point-and-Zoom, Expand, HorizontalDragger; object manipulation (grasping and moving), taxonomy of grasping, the manifold of hand postures, Natural User Interaction (NUI), PDF
8. Interaction techniques (cont'd): general 3D interaction design principles: two-handed and multimodal interaction, physical props / tangible UIs, DOF separation/reduction: PRISM metaphor and 3D widgets, action-at-a-distance (examples: image plane interaction, voodoo dolls), proprioceptive interaction, world-in-miniature, magic lenses, gimlenses, redirecting the user, redirected walking and related techniques, body retargeting, amplified head rotation, spatial illusions, system control, menus, 2D marking menus, Nielsen's usability heuristics PDF Assignment 4 Blocks
9. Particle systems: Newton's Laws, dynamics vs 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,
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, 		PDF1 PDF2 Assignment 5 Spring
10. Haptics: definitions, applications, devices, the haptic loop(s), the human haptic sense and human factors, simulation factors, haptic textures, the problems of buzzing and latency, intermediate representations, impedance vs. admittance-based approach, the surface contact point method, voxmap-pointshell method, PDF H256 VP9
11. Collision detection: motivation, definitions, collision detection pipeline, broad/narrow phase, 3D grid for filtering potentially colliding pairs, plane-sweep technique, separating planes algorithm (for convex objects) with perceptron learning rule, sphere packings, inner sphere trees, proximity computation using ISTs, penalty forces using ISTs. PDF
12. Sound rendering: motivation, human factors, mixing sound sources, image source method, beam tracing method, cell partitioning, stochastic sound-rendering of large crowds. PDF
Recommendations towards achieving the profile area "visual and medical computing" within your master's program (only for computer scientists)
Call for theses at the CGVR lab 		PDF1 PDF2

Screen Recordings of the Lecture

Here, you can find video recordings of the class taught in WS 19/20

Literature

Warning: these text books can only give you a general introduction to the field of VR! Most of the topics taught in class are not covered by any of these text books directly -- in fact, AFAIK there are some topics that are not covereed by any text book! 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 three very good internet sites for finding inexpensive used copies of books: abebooks, Booklooker, and ZVAB.

Help and Documentation on the Unreal Engine:

Online Literature and Resources from 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: Tue Nov 19 15:18:22 CET 2024