05 - Mobile Augmented Reality und Head Mounted Displays Flashcards
Was sind die Basiskomponenten eines AR Systems?
HW computational platform Display Tracking Wireless network Wearable input and interaction Software
Welche mobilen Displays werden für AR verwendet?
smartphones, tablets, konsolen, mobile projektoren
Was sind Backpack Setups?
Rucksäcke mit kompletten AR System. (semiportabel)
Warum werden Backpack Setups noch immer verwendet?
In VR more computational power is often required
Strong desire for untethered experiences
Strong desire for graphics workstations
Could be as well used for AR, especially when using AR video based HMDs
AR HMDs partially try to distribute the weight of the HMD on the head or also move the compute unit away from the head to the belt
Warum werden/wurden Mobile Devices in der AR verwendet?
Communication via Bluetooth or WiFi
Datasets are often stored externally
Processing power in PDAs and mobile consoles was sufficient for simple ARToolKit applications
If rendering power is to low
remote rendering and streaming of rendered image is possible as well
Possible to attach external screens, e.g. HMD, clip on systems,
With current devices setups are significantly more easy
Welche Mobile Devies werden verwendet?
Smart phones
iPhone, Android based phones
Often good sensor support
Tablets
Good API support
Similar development than smart phones
Mobile consoles (e.g. Gizmondo, PS Vita, Nintendo 3DS)
Provide good rendering performance
Additional controllers
Was war das Tango Projekt?
● Software architecture coupled with hardware devices
● Hardware is focused on smart phone and tablet market
● Relies on scene reconstruction with SLAM also using Time of Flight tracking
● Succeeded by Pixel series and terminated through AR Core
Welche Kommunikationsrechnologien werden bei Mobile Devices eingesetzt?
WPAN (Bluetooth, Infrared) - Short-range (10m)
WLAN - Mid-range (100m)
WWAN (LTE, GSM, UMTS, GPRS)- Wide coverage
Problems with latencies (e.g. UMTS round trip time 300-580ms ) and bandwidth
Wofür werden diese Kommunikationstechnologien in Mobile Devies verwendet?
GSM and UMTS
WLAN with the help of received signal strength indication (RSSI) by multiple access points
Was sind die Herausforderungen/Probleme bei den Mobile AR Devies?
Limited computational resources, battery life
Size, weight, robustheit(industrie)
Tracking and registration, 3D graphics and real-time performance
Social acceptance and mobility
Welche technischen Probleme treten bei Head-Mounted Displays auf?
- Systemlatenz
- Szenenauflösung
- Field of View
- Viewpoint Matchig
- Engineering and Cost Factors
hauptsächlich hardware abhängig
Auf welche Effekte des Auges muss man aufpassen bei der Enwicklung von VR/AR Brillen?
Binocular disparity - difference in image location of an object seen by the left and right eyes
Vergence - movement of the eyes to map an object on the corresponding side of the retina
Accommodation - change of lens to bring object at certain depth in focus
Welche Technologien gibt es im Stereo Display Bereich (Seperation of images)?
Spatial multiplexing - head-mounted displays
Colour multiplexing - anaglyph
Polarization multiplexing - polarisation filter
Time-sequential or shutter techniques - shutter glasse
Wie ist ein Head Mounted Display aufgebaut?
● Displays mounted inside a helmet or other kind of headgear
● Used to be Liquid Crystal Display (LCD) in earlier days Cathode Ray Tubes (CRT), today OLED and LCOS
● Head position and orientation is typically tracked (6DOF)
Warum gibt es bei Head Mounted Display ein Hygiene Problem?
Close contact to skin and eyes, users tend to sweat
For presentations or multiple users always clean the display ideally provide covers
Was sind typische technische Spezifikationen von Head Mounted Displays?
Weight (450g to 550g)
Resolution (1080×1200 pixels per eye to 1440x1600 per eye – 2560x1440 with dual display)
FOV (100° to 200° with dual display architecture)
Calibration of optics is important (interpupillary distance, exchangeable lenses)
Optics
F 14 Welche optischen Linsen werden in einem Head Mounted Display verwendet?
Fresnel lenses
Compresses space in HMD by keeping the same focal length
Leads to distortions
Special optics can be used to display the image as close as possible to the eye – Large Expanse Enhanced Perspective (LEEP)