Announcement � SGI on-campus Image-Based Graphics: � Tuesday, May 11 th Modeling, Rendering, Lighting � 10am – 5pm � In front of Building 70 � Free, but registration required � http://www.sgi.com/events/mic/rsvp.html Assignments Projects � Checkpoint 7 � Approx 22 projects � Due Monday. � Listing of projects now on Web � In Ward…no need to divide by Ldmax (already � Presentation schedule considered in sf) � Use small delta (0.0001) when calculating log- � All projects scheduled! average luminance. � Those scheduled for Monday � Final code � Anyone planning on using ICL6? � Due Monday � Anyone planning on using this laptop? � Zip or tar (rit_*.zip) � Be sure I can render (VS project files / Makefiles) Projects Logistics � Final Report � Exam day presentations � Introduction � Wednesday, May 19 th � Approach Taken � 10:15-12:15 � Implementation Details � Room 70-1435 � Results � Appendix/Code � All project material due Wednesday, May 19 th � No late submission � else I can’t get your grades in! 1
Computer Graphics as Virtual Photography real camera photo Photographic Much of the material that follows Photography: scene (captures processing print is from web pages by or light) SIGGRAPH courses organized by Paul Debevec, at USC. He processing was awarded SIGGRAPH’s first “Significant New Researcher Award” for his IBR work in 2001. camera Computer 3D synthetic tone model Graphics: models image reproduction www.debevec.org (focuses simulated lighting) Image-Based Graphics Image-Based � Use of a set of realistic images to interpolate new images from a novel point of view; i.e.., reuse of photos or previously rendered imagery � Techniques using from 2D images include � Earliest usage: � Texture Mapping � Texture mapping � Environment mapping � Morphing � Morphing � Volume Visualization � Synthetic scene creation based on other images (rather than geometry) � Image-Based Modeling, Rendering, and � Volume Visualization Lighting � IBR � Lighting � Others � Lumigraph � Light Fields � HDRI Morphing Morphing � video Blended Morphed 2
Volume Visualization Volume Visualization � Application - Medical Imaging � Used to model the characteristics of a � MRI solid region in a 2D image. � Allows zooming, rotating, and 360º viewing � Example:The density of human/animal of data � Parts of volume can be made transparent tissue computed at each 3D point through to facilitate view of other parts computer tomography (CT) from CAT or � Surgical planning MRI scans Volume Visualization Volume Visualization 3
Image-Based Modeling � Goal is to decouple rendering time and complexity; and to capture real-world complexity yet retain the advantages of 3D graphics � Has a lot in common with computer vision but goals differ � CG interested in texture and geometry. But does have issues: • View interpolation and morphing • Occluded Areas • Often high amount of user involvement http://www.debevec.org/Chevette Imaged-Based Modeling & Rendering (Movie) 4
The Chevette Project Although (and perhaps because) the final model has flaws resulting from specularities, missing concavities, and imperfect image registration, it unequivocally evokes an uncanny sense of the actual vehicle. 5
Debevec’s Modeling Method � Introduced THREE new techniques! � Photogrammetric modeling using model- based stereo algorithm � User represents scene as a collection of 3D primitives, e.g.,blocks. � Computer solves for sizes and positions of blocks according to user-supplied edge correspondence. � Rendered using view dependent texture mapping � Issues include view dependent lighting, shadows, specular reflection � May need to warp photo details to fit geometry The Campanile Movie Blurring the line between geometry and light � Our perception of object geometry is based on the light emitted from them Download the Movie! � Light stored as a 4D entity (lumigraph/light field) � Describes flow of light in all directions as precalculated and stored radiance � Ray tracing utilizes these stored values � Independently discovered and published in 1996: � Lumigraph – Gortler, et al. � Light Field Rendering – Levoy and Hanrahan The lumigraph The lumigraph � All light from an object � Each wall of the cube is actually two parallel can be represented as if planes it were coming from a � Rays are parameterized cube by where they intersect � Each point on the cube these planes has a number of rays � Any point in the 4D coming from it Lumigraph is identified by it’s coordinates (s,t,u,v) 6
Image-Based Lighting The lumigraph � Related to environment and reflection mapping � Uses light acquired in world (or thru photos) and its effects using global illumination � Probes (Debevec – http://www.debevec.org/Probes) � HDRI break 7
http://www.debevec.org/RNL/ http://www.debevec.org/RNL/ Imaged-Based Lighting (Movie) Imaged-Based Lighting (Real time Movie) 8
Radiance Maps � Environment mapping using physical lighting values. � HDRShop Demo http://www.debevec.org/FiatLux/ Imaged-Based Lighting Combined image-based modeling, rendering and lighting to place monoliths and spheres into a photorealistic reconstruction of St. Peter’s Basilica 9
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High Dynamic Range Images � OpenEXR � Introduced by Industrial Light and Magic (ILM) for their computer imagery work. � First used in � Harry Potter and Sorcerer’s Stone � Men in Black II � Gangs of New York � Signs � Now used on all ILM film effects projects. 11
High Dynamic Range Images � OpenEXR � Can encode � 9 log units of dynamic range with no loss of precision � Also supports � Compression (lossless & lossy) � Ability to store “metadata” � Arbitrary number of image channels � Compatable with Graphics hardware and Realtime Shader systems. � File format and tookit source is open source. � http://www.openexr.org Live action compositing � Environment lighting in matte painting does not effect actor. � Lightstage 3 http://www.debevec.org/Campanile/ Image-Based Graphics Live action compositing � Summary � video � Texture Mapping � Morphing � Volume Visualization � Image-Based Modeling � Image-Based Rendering � Image-Based Lighting � Used in Cinema (and Art) 12
That’s all folks � Next week: � Student Presentations � One last bit of business � Course evaluations. 13
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