Computer Graphics for Large- Scale Immersive ... - Spitz Extranet

Image BrightnessVideo Projector Brightness » Lumensbrightest video projector is 12,000 LumensTheater Brightness » Foot LambertsSMPTE standard for film is 16 ftL1 Foot Lambert = 1 Lumen over 1 Sq. . Ft.for Lambertian Screen with 100% Reflectivity

Image ResolutionAcuity of Eye = 1 arcminute/line pair1 arcminute = 1/60 degrees = 0.017ºIdeally it takes 2 pixels to represent aresolvable line pair# of Resolvable line pairs < # pixels/2

Why a Sphere?•Greater Immersivity than Flat Screen•Flat screen theoretically limited to 180º•Sphere easily provides 360º horizontal FOV•Graceful Degradation of Off-Axis Perspective•Rectilinear displays introduce artifactsi.e. CAVE

Cubic DistortionIdeal ViewpointOffset Viewpoint

Spherical DistortionIdeal ViewpointOffset Viewpoint

Theater Design• Dome Tilt•Level dome requires reclined seating•Tilted dome + stadium seating brings dome screeninto viewer’s field of view

Theater Design• Seating Configurations•Unidirectional seating provides single point of focus•Concentric seating popular in old planetariumdesigns and special applications

Theater Design Goal:When the lights go out...The theater disappears!Minimize all “reality intrusions”

Skinning a Sphere• Spherical Mastering Format (Immersoid)•Single large frame representing entire sphere•Master format for archiving, distribution, etc.•Independent of particular projection geometry•Defined only by resolution and field-of-view• Spherical Projection Format (Sub Frames)•Multi-pipe format that matches projection geometry•Sub frames individually warped and blended

Spherical Mastering Format+90ºEquidistant CylindricalLatitude0º-90º-180º 0º+180ºLongitude

Equidistant Cylindrical MasterEntire Edge Maps to Single Pixel at Pole

Equidistant Cylindrical Master

Spherical Mastering FormatLongitude0º+90º+90º-90ºPolar Fisheye(Equidistant Polar)0º-90º180º

Polar Fisheye MasteringEntireOutsideEdgeMaps toSinglePixel atSouthPolePolarImageFills78.5% ofSquareFrame

Polar Fisheye Mastering

Polar versus Cylindrical MasteringN PixelsPole-to-PoleN PixelsPole-to-PoleFile Size = 4N 2 File Size = 2N 2

Skinning a Sphere with PlatonicSolids

Skinning a Sphere - Cubic MappingFile Size > 1.5N 2Advantage - Efficient File FormatDisadvantage - Images are Discontinuous

Spherical Projection FormatsSingle Projector(Fisheye)Arrayed/MosaickedProjectors(Edge-Blended)

Fisheye ProjectionPolarFisheyeSourceImage• Simple Configuration• Limited Hemispheric Resolution (1024x1024 pixels)• Requires Obtrusive Projector Inside Theater Space

Fisheye Projection ApplicationsElumens VisionStation Series• Ideal Dome Production Monitors!• Screen Diameters from 1.6m to 5m• Resolution of 1365x1024 pixels… And GrowingImage Courtesy Elumens Corp.

Mosaicked ProjectionPolar Source isSplit Into Sub-Frames and Edge-BlendedSub Frame 1 Sub Frame 2 Sub Frame 3 Sub Frame 4

Many Projection GeometriesFive Projectors Six Projectors Seven Projectors

Mosaicking Provides SimultaneousHigh Resolution, Wide FOVWide FOV, LoResNarrow FOVHiResWide FOV, HiResSingle ChannelSingle ChannelN ChannelsMosaicked

Mosaicking Pros and Cons• “Limitless” Resolution over Chosen FOV• Greater Brightness for Given Projector Type• Master Image Must Be Parsed, Warped, Blended• Multiple Projectors to Align, Color Balance• Multiple Video Channels or Image Generator Pipes• Obviously More Complex and Costly… But• Cinematic Quality Image over Hemisphere

Volkswagen Autostadt:Hemispheric Digital Cinema3.5 Ft.L. @ 4 million pixels using 4x Barco DLP

Edge Blending and SphericalMapping Techniques• Pre-Rendered Blends and Mapping• Post-production processing of sub-frames• No special playback hardware• Realtime Blends and Mapping•Allows realtime display of CGI, video sources, etc.• Dome becomes large virtual desktop!

Pre-Rendered Edge Blends andSpherical Mapping• 2D image processing with DigiDome orPolyDome• Ad-hoc process using 3D renderer• On-site “tweaking” possible prior to processing• All immersive content must be post-processed•Live spherical images not possible

Realtime Edge Blends• Requires Edge-Blend Hardware•Panoram’s Panomaker•SEOS’s DigiBlend•Integral to Barco, Sony, 3D-Perception projectors• Control Over Blend Regions• Separate Interactive Control of R,G,B Blends• Night/Day Gamma Mapping

Realtime Spherical Mapping• Input Flat Plane, Polar, or Equidistant Source• Realtime Digital Warping•SEOS’s Mercator•3D Perception• Projector Geometry Control•Requires CRT projectors•Geometry adjustments (keystone, bow, etc.)•Orthogonal adjustments (bilinear interpolation, etc.)

Video Projector Technologies• LCoS/D-ILA - Liquid Crystal on Silicon• LCD - Transmissive Liquid Crystal Display• CRT - Cathode Ray Tube• Calligraphic CRT• DLP - Digital Light Processor• Laser Projection - Various Technologies

DLP Projectors• MEMS Mirrors on Silicon Substrate• High Contrast >1000:1• Good Resolution 1280x1024• Very High Brightness 12,000 LumensImages Courtesy Texas Instruments

LCoS Projectors• Liquid Crystal on Silicon Substrate• Excellent Pixel Fill Factor - No “Screen Door” Effect• High Contrast - up to 1000:1• High Brightness - up to 7000 Lumens• QXGA Resolution - 2048x1536 pixelsImage Courtesy JVC Corp.

CRT Projectors• Analog Technology - Continuous Image (no pixels)• Highest Resolution - 2500x2000 Addressable Pixels• Analog Image is Subject to Drift• Very Low Brightness - 270/1200 Lumens for 9” CRT• Ultra High Frame Sequential Contrast - 10 6 :1• The ONLY Projector that Fades to True Black!Image Courtesy Christie, Inc.

Calligraphic CRT Projectors• Light Points and Lines Only• Points are 1/3 the Diameter of Raster Pixels• Combination of Raster/Calligraphic Available• Digistar is Full Dome Calligraphic Star ProjectorDigistar Images Courtesy Evans & Sutherland, Inc.

Laser Projectors• Promises High Resolution, Very High Contrast• New Semiconductor-Based Solid-State Lasers• Several Competing Systems Emerging• SGI/ZEISS/Schneider Projector Optimized forDome ProjectionImages Courtesy Silicon Graphics, Inc.

Image Generation: Feeding the Dome• Pre-Rendered Video/Graphics• Digital Graphics Playback Resolutions up to1600x1200, Video Resolutions up to 1920x1080i• Pre-rendering provides superior image quality• Realtime Graphics• Provides user interactivity• Rendering speeds rapidly increasing• Live Video Feeds• Immersive Cameras• Videoconferencing• Interactive performance

Playback of Pre-Rendered Graphics• Standard Video Formats• CCIR-601 Format (720x486)– Requires expensive video line interpolators• HD 1920x1080i– 16:9 format not well suited to dome geometry• Graphics Formats• 1280x1024 provides good resolution• 1600x1200 provides excellent resolution• Multichannel Graphics/Video Servers•RAID technologies•Storage capacity in multi TB•Graphics compression available

Realtime Image Generation• Dome Systems Pioneered in Training Simulators• Immersive Visualization & VR Workspaces•CAVE, Reality Center, etc. - group interactivityImage Courtesy Spitz, Inc.

Realtime Image GenerationNetworked PC’s:(MetaVRVRSG, SGI Graphics Cluster)Image Courtesy MetaVR

Realtime Image GenerationGeForce3-based graphics cards (NVIDIA):• 1 Billion Bilinear Filtered, Multi-TexturedPixels/second• 64Mb of DDR Memory• GPU capable of 800 Billion Operations perSecond• Transform, Clip and Light 31 M Triangles perSecond• Full Scene Anti-Aliasing up to 1280x1024• Maximum Texture Map Size 2048x2048-pixels

Realtime Image GenerationMainframe Solutions Still Offer Highest PerformanceImage Courtesy Silicon Graphics, Inc.

Live Action on the Sphere...Immersive Media’s Dodecahedral CameraImage Courtesy Immersive Media CompanyFor more links: www.cis.upenn.edu/~kostas/omni.html

TelepresenceCMU’s Nomad Robot Tested by NASA Ames inAtacama Desert… Live Audience Telepresencehttp://www.cs.cmu.edu/afs/cs/project/lri-13/www/atacama-trek/

Immersing the WorldSpecial Thanks to:Elumens Corp.Evans & SutherlandMetaVRSilicon Graphics Corp.Spitz, Inc.