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Display Tele-Vision Mechanical - Mechanical Photocell Neon Tube Photocell 1877 Proposed Mechanical Scanning 1884 Invented Circular Mechanical Scanner 1925 Mechanical TV system was achieved 1897 Cathode-ray tube (CRT) was invented 1911 Cathode-ray tube was used to display a simple image. Tele-Vision Mechanical - Electrical 2011/1/20 Google doodle (Kenjiro Takayanagi) テレビ伝送実験装置の再現展示(NHK放送博物館@東京都港区愛宕山) Tele-Vision Electrical - Electrical Iconoscope 1927 All electrical system was achieved. 1929 BBC starts experimental TV broadcast. 1935 Germany starts first periodical TV broadcast, and was used for Berlin Olympics Display technologies CRT cathode ray tube Only one point of fluorescent substance ( on the surface receives electrons and emits light. Scanning ( ) is necessary. Raster scan Pixel ( scan ) based Vector scan Draw figures by lines. Do not use pixel. ) Display technologies LCD (Liquid crystal display) PDP (Plasma display panel) Field Emission Display Organic light emit diode (OLED) Display technologies Projectors CRT Digital Mirror Device Digital Light Processing LCD (Three panel) Liquid Crystal On Silicon Mirror type LCD B Color Space Put all colors in a 3D space 3 types of cone cells→3D CIE ( C o m m i s s i o n i n t e r n a t i o n a l e d e l ‘ é c l a i r a g e ) -RGB color space 3 basis( ): R(700nm), G(546.1nm), B(435.8nm) Additive mixtures( ) are represented by sum of bases. Some colors requires negative R. R G RGB color space y XYZ color space G Change basis from RGB to XYZ. XY Z is imagin ary co lo r Y: Lu min an ce ( ) Avo id n e gat ive valu e s fo r all co lo rs. xyY color space Represent color by x, y. Represent Luminance by Y 𝑋 𝑌 𝑥= ,𝑦 = 𝑋+𝑌+𝑍 𝑋+𝑌+𝑍 R YUV color space ≈YCbCr color space ≈ Yzx JPEG, MPEG,TV uses this color space B x CIE 1931 color space chromaticity diagram Display and color space 16 primary color camera 6 primary color display RGB color display Human perceptible color 6 primary color display Display and color space primary color TV Comparison of three and four http://www.sharp.co.jp/aquos/technology/quattron/ Dynamic range of brightness Dynamic range of human vision: 10 8 (Starry sky - direct sunlight) Iris diameter of pupil Sensor (Sensitivity : amount of Rhodopsin in cells) High Dynamic Range Display Projector + Liquid crystal LED + Liquid crystal OLED (Organic Light Emitting Didode) ( EL LED) Visual display for virtual reality 3D space Wide filed of view Images change according to eye position Immersive( ) displays Head Mounted Display(HMD) piSight 180 degree 2600x1600 Multi Projection Oculus DK 2 960x1080 110度x90度 Gyro, accelerometer, compass Oculus Rift 2160x1200 110degrees HMD Immersive Projection Technology(IPT) D-vision CAVE Immersive( ) displays IPT Rotating LED array Multiple projectors IMAX/Omnimax Projection to wide/spherical screen with wide angle/ fisheye lens resolution can be problem Twister (Tach lab.) HMD HMD as a magnifying glass Two separate images are displayed to each eye. Head posture is tracked by, Mechanical Link, Gyro Acceleration Sensor Magnetic Sensor etc… “Magnifying glass” optics is used to keep distance between eye and image. HMD Camera for HMD Two cameras, which are at the same position as the HMD are used. TELESAR Tachi et al., http://tachilab.org/modules/projects/telesar.html Other concerns(1) Eye distance & view angle Difference of eye distances generate odd size feeling (miniature garden) Difference of viewing angle Distance is changed. When head rotates, objects move to stick in the field of view. Uncomfortable feeling of wearing eyeglasses at the first time. Other concerns(2) Time Latency Latency between head motion and image display When the head rotates: The image moves Oculus rift and Microsoft hololens predict motion of display and compensate the delay. Head Motion Image transfer Microsoft Hololens, an AR HMD In AR, delay can be felt between naked eye image and displayed image → more severe. Pros & Cons of HMD / HMD Users can walk freely / Users can hide their bodies, meaning they can “deceive” themselves. Becomes robust to latency and coordinate distortion. / Heavy and feeling of being caged / Face is hidden, meaning two way communication is difficult / Design of large field of view is quite difficult / Augmented Reality (AR) and See-Through HMD Overlap virtual world (CG image) and the real world Video See-Through Optical See-Through Capture the real world by camera. Use half-mirror & optically overlap See-Through HMD (video see-through) Problem of AR (1) Focal distance HMD image is always at the same distance. Distance of real world object is arbitrary User can’t clearly observe the two simultaneously. Video see-through partially solved the problem, but the real world image is different due to large depth camera. Problem of AR (2) Occlusion (A) Ordinary HMD (B) Ideal occlusion (C) See-Through HMD (D) Ground fixed display (projector and large screen) Solution of Problem of AR(2) Occlusion Kiyoshi Kiyokawa et.al. 2000 25 HMD Retina scan display Washington university, HIT Lab(‘99) Scan retina by laser beam Image focus by the eye lens is unnecessary Problem of focal distance is solved. C&D Electronics Red Laser Diode Delivery Optics Argon Laser Scanners AO Modulators http://www.hitl.washington.edu/projects/vrd/ Retina Scan display by Brother Inc. MEMS Light scanning Relay lens device Image on retina Sync signal rays Pupil Retina Image signal Light source Production as AiR Scouter http://www.brother.co.jp/product/hmd/wd100ga/ Retina Scan display by Brother Inc. http://www.youtube.com/watch? v=CYBw-5plmmI 28 Head Mounted Projector by Retroreflector http://projects.tachilab.org/rpt/ Model 1: 1998 Model 2: 1999 Model 3: 2003 What is retro-reflector? Glass balls with index of refraxtion=2 Or, Cube type (Corner Cube) Any incident beams will come back to the same direction. インタラクティブ技術特論 RPT: Retro-reflective Projection Technology •Use retroreflector and projector •Problem of focal distance is solved. •Problem of occlusion is solved. •Stereoscopic image can be presented Tracking methods for HMD or human motion mechanical magnetic Optical Accelerometer, gyroscope, magnetometer Magnetic trackers Polhemus Fastrak Ascension Flock of Birds Mechanical Ivan Sutherland (1968) 1st HMD was see through Augmented Reality ⇨ will mention later Potential meter Graphics Reflecting head orientation 35 Magnetic Position Sensing Put AC voltage on three transmitter coils one by one. Voltage on three receiver coils results nine voltages The length of the vector → position Direction of the vector → orientation receiver 1/3 or Transmitter Optical Opto Trak Northern Digital Inc. Maximum 2D Accuracy Maximum 3D Accuracy Maximum update rate Resolution 0.1 mm 0.15 mm 4600 Hz 0.01 mm • LED maker emit light • position sense diode measure direction of light source • Estimate maker by triangulation (三角測量) Image on immersive projection displays Also update based on view point. CAVE 3D display Depth cue Monocular cues, With single eye Experience Accommodation Motion Parallax Update image based on view point Binocular cues, With two eyes Vergence eye movement Binocular disparity Different images for each eye. → Aims to show image based on view point. Meaning of update based on view point. Difference between TV and window Update image based on view point = window to virtual world. TV Window Binocular display Present different image to left and right eyes. Stereo display 41 Anaglyph With red and cyan (green + blue) glasses Blue and yellow(red + green) is also possible binocular rivalry ( blinking by turns. ) tends to occur. Left and right images Polarizer Polarizer film polarization preserving projection screen… is not very common. Reflection type: Silver screen Transmission type: Near to transparent and no fiber. You have to test then to choose. Polarizer film Wave length band pass filter User different wave length for each eye H. Jorke, A. Simon and M. Fritz 2008 Time-sequential method Liquid crystal shutter glass Battery is needed One of lens comes to dark. Synchronized by IR emitter. High refresh rate is required For binocular→120Hz is good Liquid crystal on Projector/Monitor No battery polarized glasses are enough One projector can present left and right images 3D TV with glass usually show 60Hz for monocular, Show image during 1/240 second.(L→dark→R→dark) Naked eye (glass less) 3D display Volume scan display Display emits light from 3D object’s shape. Varifocal mirror display Swept-volume display (Super) multi view display Show images corresponding to view point position Integral Photography Parallax barrier Lenticular lens Volume scan display Varifocal mirror display Swept-volume display CRT display Varifocal mirror Volume scan display Swept-volume display Volumetric 3D Display by Actuality Systems Volume scan display Lighting air Super strong IR laser makes super strong electric field at the focal point. → air comes to plasma → emitting light Lighting air with femtosecond (10 -15 sec) laser 50 Naked eye, binocular 3D display Lenticular lens Parallax barrier Parallax barrier Aperture / Slit Image Right eye Image Left eye L R Lenticular lens For cell phones and LCD monitor View point must be fixed FIY: Nintendo 3DS like 2D/3D switch Block rays TFT LC LC for 3D Parallax barrier Back light Back light Liquid crystal layer for parallax barrier 2D/3D mode change http://www.sharp.co.jp/products/device/about/lcd/3d/index.html Multi viewpoint by Lenticular lens For left and right direction vertical viewpoints are omitted. 9 view point glassless 3D by Toshiba http://www.toshiba.co.jp/regza/option/gl1/quality.html より Binocular display by Lenticular lens L R Lenticular lens Image Many image pixels for many viewpoint. One can move view point Integral photography Photograph with fly’s eye lens ( ) Lens The color of each lens differ for directions Image on the film Reproducing light field ( , ) Problem on volume scan display Hidden line removal Transparent, backside can be seen is impossible Integral Photography reproduce light filed. Position and direction of rays (light field) is reproduced The color and brightness differs in direction at each pixel. Example of reproduction of light field Cylindrical light field display No transparency problem RePro3D (T. Yoshida et al. 2010) Projector array Retroreflector Half mirror Projector array and retroreflector (再帰性反射 材) generate eye position dependent images. http://www.jst.go.jp/pr/announce/20101012/index.html Light field displays Interactive 360 Light Field Display by Paul Debevec Light field displays 60 Hologram not a “holographic display”, real horography Diffraction grating reproduce light field Recording a hologram (Making diffraction grating) Laser light Reconstructing a hologram Holograms Explanation of hologram by equations Electric filed of a coherent light wave can be written as 𝑈 = 𝐴 𝑥, 𝑦, 𝑧 sin(𝜔𝑡 + 𝜙(𝑥, 𝑦, 𝑧)) = Re 𝐶 𝑥, 𝑦, 𝑧 𝑒 𝑖𝜔𝑡 (𝐴, 𝜙 are real numbers, C is a complex number) 𝑈𝑜 : reflection from object, 𝑈𝑅 :reference light, 𝑈𝐻 light from hologram Recording 𝑇, Transparency of the film is proportional to light intensity on the film 𝑇 = 𝑘 𝑈𝑜 + 𝑈𝑅 2 = 𝑘 (𝑈𝑂 𝑈𝑅∗ + 𝑈𝑅 2 𝑈𝑅 𝑈𝑜 𝑈𝑅 + 𝑈𝑂 2 +𝑈𝑂∗ 𝑈𝑅 ) Play 𝑈𝐻 = 𝑇𝑈𝑅 = 𝑘𝑈𝑂 𝑈𝑅 2 𝑈𝐻 + 𝑘 𝑈𝑅 2 𝑈𝑅 + 𝑘 𝑈𝑂 2 𝑈𝑅 + 𝑘𝑈𝑂∗ 𝑈𝑅2 ) The first term is proportional to 𝑈𝑂 (reflection from object) = the hologram image. 63 Pseudo 3D by 2 stacked images Space Illusion DFD (Depth Fused 3D Display) (NTT lab invented) Front image plane Back image plane Viewer 2D image 3D image is perceived 2D image http://www.ntt-it.co.jp/goods/idp/dfd/principle.html Pulfrich Effect (another illusion for 3D) Fast Slow Put eyeglasses with two different darkness for each eye Different brightness generates temporal difference Horizontal motion of the movie causes disparity, generates 3D feeling Is 3D display really necessary? Maybe, but not for all works Yet too expensive, and contents are limited. To “observe” something, resolution is more important than 3D. (You can observe with single eye!) However, To handwork in a virtual space, “distance” perception between myself and the CG object is critically important. Illusion by floating image When the image is floating in the air, we feel it as 3D 3D images are float from the display. Real 3D displays also make floating images. When we see a floating image, we feel it is an 3D object not an picture on a wall 3D image Display plane Floating Vision , 2008) Image on display Micro Lens arra http://www.schaft.net/n00bs/201 0/02/24230148.html Floating image ,2008) http://www.youtube.com/watch?v=Wzx9zid_FoA Fog Screen http://www.fogscreen.com/ Water drop screen 71 Water drop multi viewpoint 72 (Rayleigh scattering) (Mie scattering) Rayleigh scattering: particle size is smaller than 1/10 of wave length. Mie scattering : particle size is larger than wave length The larger particle makes the more transmission Wave length of light: 0.4μm Cloud:3 0.7μm 10μm, Rain drop:0.1mm Rayleigh scattering 5mm Mie scattering 73 Half transparent screen (completely different from half mirror) http://www.youtube.com/watch?v=YH7S0lQ94nc http://www.youtube.com/watch?v=rqg4Eun7fgs Lumisight Table (Kakehi et al., 2003) Light control film “Lumisty”: works both as diffuser and transparent film for different angle. Viewer Lumisty Glass Transparent Scattered Light control film Lumisty Scatter transmission A section observation Straight transmission 76 Lumisight Table (Kakehi et al., 2003) 4 Different images for different user Simultaneous motion analysis is possible using transparency インタラクティブ技術特論 Using eye movement 2 kinds of eye motion Smooth Pursuit (滑動性追跡眼球運動) Saccade(跳躍性眼球運動) LED sign board using smooth pursuit Avix Polevision http://www.youtube.com/watch?v=KhpMzNYetis Saccade Based Display (Watanabe et al) Saccade makes large jump Writing image at that time: one LED light (You can experience it at Odaiba Mediage SonyExplorascience 5F Present image at the instance of saccadic eye movement, using linear LED array http://www.junji.org/saccade/index.html Saccade Based Display (Watanabe et al.) http://www.youtube.com/watch?v=d_pjvSt3w18 インタラクティブ技術特論 Mini Test 100 Answer all questions within 50 words 1. HMD Explain the role of convex lens in HMD. 2. Explain how to realize full -color stereoscopic display by wavelength filter. 3. Explain by figure how to achieve parallax by lenticular lens 4. Explain by figure how to achieve parallax by barrier. 5. Explain Pulfrich effect 6. AR HMD What are two types of HMD for AR? 7. AR Explain problem related to focal distance in AR system 8. AR Explain problem related to occlusion in AR system.