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AUG - Augmented Reality > 05 - Mobile Augmented Reality und Head Mounted Displays > Flashcards

05 - Mobile Augmented Reality und Head Mounted Displays Flashcards

1
Q

Was sind die Basiskomponenten eines AR Systems?

A 
 HW computational platform 
 Display 
 Tracking 
 Wireless network 
 Wearable input and interaction 
 Software
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2
Q

Welche mobilen Displays werden für AR verwendet?

A

smartphones, tablets, konsolen, mobile projektoren

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3
Q

Was sind Backpack Setups?

A

Rucksäcke mit kompletten AR System. (semiportabel)

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4
Q

Warum werden Backpack Setups noch immer verwendet?

A

 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

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5
Q

Warum werden/wurden Mobile Devices in der AR verwendet?

A

 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

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6
Q

Welche Mobile Devies werden verwendet?

A

 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

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7
Q

Was war das Tango Projekt?

A

● 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

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8
Q

Welche Kommunikationsrechnologien werden bei Mobile Devices eingesetzt?

A

 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

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9
Q

Wofür werden diese Kommunikationstechnologien in Mobile Devies verwendet?

A

 GSM and UMTS

 WLAN with the help of received signal strength indication (RSSI) by multiple access points

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10
Q

Was sind die Herausforderungen/Probleme bei den Mobile AR Devies?

A

 Limited computational resources, battery life
 Size, weight, robustheit(industrie)
 Tracking and registration, 3D graphics and real-time performance
 Social acceptance and mobility

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11
Q

Welche technischen Probleme treten bei Head-Mounted Displays auf?

A
  • Systemlatenz
  • Szenenauflösung
  • Field of View
  • Viewpoint Matchig
  • Engineering and Cost Factors

hauptsächlich hardware abhängig

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12
Q

Auf welche Effekte des Auges muss man aufpassen bei der Enwicklung von VR/AR Brillen?

A

 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

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13
Q

Welche Technologien gibt es im Stereo Display Bereich (Seperation of images)?

A

 Spatial multiplexing - head-mounted displays
 Colour multiplexing - anaglyph
 Polarization multiplexing - polarisation filter
 Time-sequential or shutter techniques - shutter glasse

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14
Q

Wie ist ein Head Mounted Display aufgebaut?

A

● 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)

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15
Q

Warum gibt es bei Head Mounted Display ein Hygiene Problem?

A

 Close contact to skin and eyes, users tend to sweat

 For presentations or multiple users always clean the display ideally provide covers

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16
Q

Was sind typische technische Spezifikationen von Head Mounted Displays?

A

 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

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17
Q

F 14 Welche optischen Linsen werden in einem Head Mounted Display verwendet?

A

 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)

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18
Q

F 14 Was ist der Screen Door Effect?

A

 Depending on the resolution or better the distance between pixels (pixel gaps)

 The determining factor is the gap size during magnification, resolution is not immediately related to it

 Resolution is significantly increasing and the gap sizes are decreasing

19
Q

Welche Head Mounted Displays gibt es?

A

Oculus Rift, HC Vive, Microsoft MR headsets

20
Q

F 16 Was sind optical see through HMDs?

A

 Partially transmissive/reflective optical combiners
 Similar approach to Head-Up Displays (HUD)
 Light from the real world is reduced (e.g. 30% transmitted)
 Could be designed to omit real-world light at a certain wavelength
 Level of blending is design issue
 Optical blending requires no additional computing power

21
Q

F 16 Was sind video see through HMDs?

A

 Closed-view HMD with one or two cameras
 Possible to fully occlude real world
 Combination is performed by a video compositor
 Much more flexible than optical see-through displays in compositing strategies
 Used for diminished reality or mediated reality

22
Q

F 16 Was sind video see through HMDs?

A

 Closed-view HMD with one or two cameras
 Possible to fully occlude real world
 Combination is performed by a video compositor
 Much more flexible than optical see-through displays in compositing strategies
 Used for diminished reality or mediated reality

 Chroma-keying often used for combination of real and virtual images (known from blue box, green box)
 Use of depth information would be helpful in order to allow real objects cover virtual ones (e.g. combination Leap Motion and Oculus Rift)
 Separate video streams are needed for real and virtual world, thus computationally more expensive than optical blending
 Resolution is limited, thus resolution of the real world objects is reduced
 Artificial offset due to position of recording cameras
 Interpupillary distance (IPD) may not be exact
 Additional registration strategies can be applied through the use of the video stream
 Temporal mismatches between real and virtual image can be matched

23
Q

Was sind die Vorteile von optical see through HMDs?

A

 Simplicity
 Optical blending is computationally much cheaper than video blending
 One stream is rendered in optical blending, two with video based systems
 Roughly one frame delay with video systems is added
 Field Of View (FOV) is not a major issue with optical blending
 Video cameras produce distortion, which has to be compensated

 Resolution
 Video blending limits the resolution to the display resolution
 With optical combiners only the CG generated resolution is limited
 Display of the real world is not degraded

 Safety
 In case of power loss a direct view on the real world is still available
 Depending on the application area this can be an issue (e.g. fire fighting)

 No eye offset
 With video displays the cameras are located in most cases not directly in front of the eyes
 IPD is often different with video see-through
 Mirrors might be used to overcome the offset problem, adds complexity to the design of the HMD

24
Q

Was sind die Vorteile von video see through HMDs?

A

 Flexibility in compositing strategies
 With optical see-through objects can not fully obscure real world
 CG objects are always semi-transparent in optical see-through systems
 With video blending composition can take place on a pixel-by-pixel basis

 Additional registration strategies
 Video stream provides additional source of information for registration

 Easier to match brightness of real and virtual objects
 With real world a high and dynamic range of brightness has to considered
 If real environment is too bright the CG image will be washed out
 If real world image is too dark CG image will wash out the real world image

 Limited FOV provides a disadvantage
 Complex optics add weight and can be expensive
 Distortions of real world image have to be corrected optically with optical blending

 Real and virtual view delays can be matched
 Temporal mismatch problems can be avoided
 Video stream can be delayed for matching CG stream

25
Q

Was sind Sulon Cortex und Vrvana Totem?

A

 Stereo cameras integrated for see-through mode
 Camera calibration is non-trivial, offsets are to be considered
 Vrvana acquired by Apple in 2017

HMD ist video based
Auf mixed reality ausgelegt

26
Q

F 22 Was ist die Varjo XR1?

A

● Varjo XR1
 Extension of the VR1 with additional cameras

● Illustrates advantages of video based see-through
 Larger FOV  Adaptation of lighting situation
 Merged video stream provides better contrast

● Current trend to move away from dedicated MR displays and integrate functionality in existing VR displays

27
Q

F 22 Was ist die Varjo XR1?

A

● Varjo XR1
 Extension of the VR1 with additional cameras

● Illustrates advantages of video based see-through
 Larger FOV  Adaptation of lighting situation
 Merged video stream provides better contrast

● Current trend to move away from dedicated MR displays and integrate functionality in existing VR displays

28
Q

Was sind Smart Glasses?

A
  • optical see through
     Typically light weight and comfortable to wear
     Small FOV, focus on information representation, rather than registered augmentations
     Current devices applicable for specific use case
29
Q

Welche Smart Glasses gibt es und welche Spezifikationen haben sie?

A

● Epson Moverio BT-300
 Stereoscopic OLED display  HD camera with 6h of battery life
 Android based App development, external Android device

● Google Glass
 Monoscopic 640×360 LCoS Display
 Variety of sensors (e.g. gyro, accelerometer, compass)
 Focus also on speech recognition  Second Edition available from summer 2017 till November 2019

Neuer:
● Vuzix Blade
 Uses touch display and voice recognition for interaction
 Camera supports 720p 30fps or 1080p 24fps
 Waveguide DLP based display
 Android based OS, ARM CPU on device

Neuer:
● Vuzix M400 Smart Glasses
 Monocular device using video blending
 Powerbank as counter weight
 Can be mounted on helmets or safety glasses
 Ruggedised design

30
Q

Welche Verfahren gibt es um optical HMD zu ermöglichen?

A

 Prism Lenses
 Output from miniature projector is projected into special prism lens, where light propagates via internal reflection and refraction
 E.g. Google Glass

 WaveGuide Arrays
 Light is projected inside an array of wave guides
 Different approaches of extracting light of wave guides into the eye
 Holographic extraction
 Diffractive extraction

 Half-silvered mirrors
 E.g. Meta2

31
Q

Was macht die HoloLens aus?

A

 Based on see-through waveguide lenses (optical)
 Untethered
 Big advance in terms of tracking and registration

32
Q

Welche Viewing Area hat die HoloLens?

A

 Focal plane at around 2m

 Ideal object placement between 1.25m and 5m

33
Q

Welche Field of View Rextrictions hat die HoloLens?

A

FOV restrictions (30°)
 Object permanence might be broken due to limited FOV
 Remember FOV constraint when designing applications
 Peripheral vision is not available with HoloLens augmentations

34
Q

Welche Interaktionsmöglichkeiten hat die HoloLens?

A

 Gaze, Gesture, and Voice
 Speech (with 4 microphones quite possible to filter out ambient noise)
 Clicker (connected via Bluetooth)
 Gesture recognition (abstract gestures)
 Gaze based selection, AirTap for clicking

35
Q

Welche technischen Spezifikationen hat die HoloLens?

A

 Price 3.000$
 Weight: 579g
 Resolution: 2.3M total light points results in roughly 2x1268x720
 FOV: 29.1×16.5° diagonal 33.4°

 Sensors: 
      IMU 
      4 environment understanding cameras 
      1 depth camera 
      1 2MP photo / HD video camera 
      Mixed reality capture 
      4 microphones 
      1 ambient light sensor
36
Q

Welche Features und Limitationen hat das headmounted display Meta2?

A 
 Tethered, try to become untethered 
 Large FOV 
 Different interface approach 
 Uses Unity for development 
- optical blending
- Haben versucht die Brille physikalischer zu machen, dass man direkt mit etlichen handgesten Sachen natürlicher verschiebt/verändert/damit interagiert
37
Q

Welche technischen Spezifikationen hat die Meta2 Brille?

A

 Price 1.000$
 Weight: 420g (without straps and cables)
 Resolution: 2x1280×1440
 FOV diagonal 90°

38
Q

Welche Interaktionsmöglichkeiten hat die Meta2?

A

 Direct interaction (pushing buttons on menus, grabbing objects by showing a fist)
 Supposedly still pretty basic
 Problem with objects at distance
 Issues with tracking stability and latencies

39
Q

Was ist das DAQUIRI HMD?

A

 Smart helmet (rugged design)
 Comes with camera and sensing equipment like IR projectors and IR camera
 Additional thermal camera
 Intel RealSense

  • optical hmd
40
Q

Was ist das ODG R-7 HMD?

A

 Dual 720p Stereoscopic See-through displays at up to 80fps
 Variety of sensors including altitude and humidity
 Full HD camera
- optical hmd

41
Q

Was ist die MagicLeap One und was zeichnet sie aus?

A

 Bi-focal display to reduce focus problem
 Eye-tracking used to select appropriate focal plane
 Compute unit external moved away from head (Lightpack)
 Side areas blinded, which gives the impression of a larger FOV
 6DOF Controller with magnetic tracking
 Available in two versions for different IPDs
 FOV slightly higher than MS HoloLens
 128 GB (actual available storage capacity 95GB)
 Up to 3 hours continuous use
 Vast amount of funding (roughly 2.4 billion US$)
 Support of many artists and companies (e.g. Sigur Rós, WETA)
- optical hmd

42
Q

Was ist die HoloLens2?

A

● HoloLens2
 Announced 24.02.2019  Pre-order: $3500
 FOV 52° Diagonal
● Eye tracking for measurement and calibration of the IPD also interaction
● Available sometime 2019
● Weight with compute unit has been moved into the back of the device that the overall weight is balanced putting the centre of gravity in the middle of the head
● Semantical analysis of the environment
● Use of over 20 gestures for interaction
● Gesture tracking is reliable

43
Q

XX Welche Brillen verwenden optical blending?

A

HoloLens 1 und 2, Magi Leap One, ODG R-7, DAQIRI, Meta2

44
Q

Was sind die größten Unterschiede zwischen Smart Devices, Smart Glasses und HMDs?

A

● Smart Devices (tablets, phones)
 Provide intuitive and to the user well kown interaction
 Have to be held
 Mainly monoscopic

● Smart glasses
 Low weight
 Reduced interaction possibilities
 Very low FoV

● HMDs 
      Hands-free interaction 
      Encumbrance of the user 
      Stereoscopic 
      Low FoV
      - noch nicht industrietauglich

AUG - Augmented Reality (7 decks)

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