What is a system? (Englander)
A collection of components linked together and organized in such a way as to be recognizable as a single unit
described by structure and purpose.
delimited by boundaries (spatial, temporal, contextual, etc.)
interacting with the environment.
expressed by their functions.
Why do humans group components into systems… and represent them as abstractions?
To simplify understanding and analysis (especially if numerous and complex).
To study component relationship(s) (especially without distraction by details).
To decompose, isolate, and study individual components when required.
Fülle das Modell aus
Describe the Components of a System
Interface handles I/O with environment.
Processor transforms I to O. (Operation Making)
Control controls the patterns of activity. (Decision Making)
Feedback supervises/optimizes operation (optionally for dynamic systems). (self-Performance Evaluation)
Fülle das Modell aus (A simple control system with one sensor and one actuator)
What are the Definitions of a Real-time-system?
A computer system used primarily to measure external events that happen in ’’real time";
that is, the events require quick processing because data is of critical time-sensitivity. (Englander 2009
A computational system that offers an assurance of timeliness of service provision.
A computational system where the correctness of the system behavior depends - on the logical results of the computations, and also - on the physical time when these results are produced.
All missed deadlines lead to system failure.
Infrequent missed deadlines are tolerated but may degrade overall QoS. Delayed results are useless.
Missed deadlines degrade the usefulness of the respective results and hence degrade the overall Quality of Service (QoS).
What are the Definitions of an interactive System?
When the system is interactive, the user interacts directly with the program to provide input data and guidance during program execution (Englander 2009).
A computer system as an interactive artifact.
Fülle das Modell aus (A human-computer system with one sensor and one actuator.)
What is the Definition of Interactivity?
Experienced behavior of an artifact caused by user’s actions (control) as perceived through use of the artifact’s interface.
What is the Defintion of Reactivity?
A characteristic of an interactive system determined by the end-to-end latency.
Definition of End-to-End Latency?
Temporal delay between a user’s action and a causally expected user-perceivable result.
What is sampling (concerning T)?
The reduction of a continuous signal to a discrete signal.
What is reconstruction (concerning T)?
The conversion of a discrete signal to a continuous signal
Missed synchronization between modalities (faulty timing) might…
cause artifacts (e.g., tearing), and/or
compromise usability and user experience, and/or
even cause psychophysical problems (e.g. cybersickness).
What are facts about independent timing?
are a requirement for multiple modalities.
are a requirement for independent simulation loops.
are (possibly) subject to real-time constraints.
Interactive system synchronizing multiple concurrent modalities (input and output forms and devices) and simulations (or computations) of different timings, which are partly subject to firm or hard real-time performances due to high reactivity and consistency requirements (aka perceptual constraints).
Fill the simple game loop
Other simulation/game engines similar (e.g., UE4).
Does not utilize multi core architectures well.
Problem inherently difficult due to data dependencies between stages.
Parallelization to be performed per stage.
Above which latency in VR Systems is it harmful?
above is harmful: cybersickness, low immersion, impossible to perform a task
Application (fast/slow paced game)
task (pointing, tapping, clicking dragging)
system (VR, Touchscreen, desktop)
people, see Deber u. a. (2015) for overview.
Separates input and output regions and requires a pointing tool such as a mouse, touchpad, or stylus to provide information to the computer.
or losing consistency of user’s motion detection (missing gesture, wrong head tracking = wrong )
or losing consistency of surface/shape physical properties (feel wrong texture or shape)
or Losing illusion of intelligence (low reactive agent/too slow)
or losing audio consistency (glitches)
or losing illusion of continuous motion (animation)
or losing collision consistency (tunneling effect), miscomputation,…
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