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Real-Time High Quality Rendering COMS 6160 [Fall 2004], Lecture 1 Ravi Ramamoorthi http://www.cs.columbia.edu/~ravir/6160
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Motivation Today, we create photorealistic computer graphics Complex geometry, realistic lighting, materials, shadows Computer-generated movies/special effects (difficult to tell real from rendered…) But algorithms are very slow (hours to days)
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Real-Time Rendering Goal is interactive rendering. Critical in many apps Games, visualization, computer-aided design, … So far, focus on complex geometry Chasm between interactivity, realism
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Evolution of 3D graphics rendering Interactive 3D graphics pipeline as in OpenGL Earliest SGI machines (Clark 82) to today Most of focus on more geometry, texture mapping Some tweaks for realism (shadow mapping, accum. buffer) SGI Reality Engine 93 (Kurt Akeley)
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Offline 3D Graphics Rendering Ray tracing, radiosity, photon mapping High realism (global illum, shadows, refraction, lighting,..) But historically very slow techniques “So, while you and your children’s children are waiting for ray tracing to take over the world, what do you do in the meantime?” Real-Time Rendering Pictures courtesy Henrik Wann Jensen
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New Trend: Acquired Data Image-Based Rendering: Real/precomputed images as input Also, acquire geometry, lighting, materials from real world Easy to obtain or precompute lots of high quality data. But how do we represent and reuse this for (real-time) rendering?
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5 years ago High quality rendering: ray tracing, global illum., image-based rendering (This is what a rendering course would cover) Real-Time rendering: Interactive 3D geometry with simple texture mapping, maybe fake shadows (OpenGL, DirectX) Complex environment lighting, real materials (velvet, satin, paints), soft shadows, caustics often omitted in both No COMS 6160: Realism, interactivity at cross purposes
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Outline of Lecture Background Motivation, effects for high quality real-time rendering Recent technological, algorithmic developments Preview of results currently possible Logistics of course
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High quality real-time rendering Photorealism, not just more polygons Natural lighting, materials, shadows Interiors by architect Frank Gehry. Note rich lighting, ranging from localized sources to reflections off vast sheets of glass.
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High quality real-time rendering Photorealism, not just more polygons Natural lighting, materials, shadows Real materials diverse and not easy to represent by simple parameteric models. Want to support measured reflectance. Glass Vase Glass Star (courtesy Intel) Peacock feather
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High quality real-time rendering Photorealism, not just more polygons Natural lighting, materials, shadows Natural lighting creates a mix of soft diffuse and hard shadows. Agrawala et al. 00 small area light, sharp shadows soft and hard shadows Ng et al. 03
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Demo
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Applications Entertainment: Lighting design Architectural visualization Material design: Automobile industry Realistic Video games Electronic commerce
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Outline of Lecture Background Motivation, effects for high quality real-time rendering Recent technological, algorithmic developments Preview of results currently possible Logistics of course
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5 years ago High quality rendering: ray tracing, global illum., image-based rendering (This is what a rendering course would cover) Real-Time rendering: Interactive 3D geometry with simple texture mapping, maybe fake shadows (OpenGL, DirectX) Complex environment lighting, real materials (velvet, satin, paints), soft shadows, caustics often omitted in both No COMS 6160: Realism, interactivity at cross purposes
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Today Vast increase in CPU power, modern instrs (SSE, SIMD, …) Real-time raytracing techniques are possible 4 th generation of graphics hardware is programmable (First 3 gens were wireframe, shaded, textured) Modern nVidia, ATI cards allow vertex, fragment shaders Great deal of current work on acquiring and rendering with realistic lighting, materials… [Especially at Columbia] Goals of COMS 6160: Understand these new ideas for high- quality rendering, and recent literature (last 5 years) (This is not a course about real-time rendering with complex geometry. It is primarily about high quality shading effects)
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Outline of Lecture Background Motivation, effects for high quality real-time rendering Recent technological, algorithmic developments Preview of results currently possible Programmable graphics hardware Precomputation-based methods Interactive RayTracing Logistics of course
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Programmable Graphics Hardware Nvidia dusk demo http://www.nvidia.com/object/demo_dusk.html http://www.nvidia.com/object/demo_dusk.html
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Precomputation-Based Methods Static geometry Precomputation Real-Time Rendering (relight all-frequency effects) Involves sophisticated representations, algorithms
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Relit Images Ng, Ramamoorthi, Hanrahan 04
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Video: Real-Time Relighting Followed by demo with real-time relighting with caustics
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Interactive RayTracing Advantages Very complex scenes relatively easy (hierarchical bbox) Complex materials and shading for free Easy to add global illumination, specularities etc. Disadvantages Hard to access data in memory-coherent way Many samples for complex lighting and materials Global illumination possible but expensive Modern developments: Leverage power of modern CPUs, develop cache-aware, parallel implementations
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Interactive Ray-Tracing Video
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Outline of Lecture Background Motivation, effects for high quality real-time rendering Recent technological, algorithmic developments Preview of results currently possible Logistics of course
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Course Goals, Format Goal: Background and current research on high- quality real-time rendering in computer graphics Columbia is one of the best places for this!! Format: Alternate lectures, student presentations of papers http://www.cs.columbia.edu/~ravir/6160/
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Course Logistics No textbooks. Required readings are papers available online (except 2 handouts today) The book “Real-Time Rendering (2 nd ed)” by Moller and Haines may be helpful (though we will not follow it closely) Office hours: before class. My contact info is on my webpage: http://www.cs.columbia.edu/~ravir Counts for PhD elective breadth in graphics/HCI, MS elective for vision/graphics, BS elective etc.
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Requirements Pass-Fail Show up to class regularly Present 2 (maybe 1 if enough people) paper(s) Prefer you do this rather than just sit in Grades Attend class, participate in discussions (10%) Present 3 (maybe 2 if enough people) papers (30%) Project (60%)
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Project Wide flexibility if related to course. Can be done in groups Default: Implement (part of) one of papers and produce an impressive real-time high quality rendering demo See/e-mail me re ideas Best projects will go beyond simple implementation (try something new, some extensions) Alternative (less desirable): Summary of 3+ papers in an area Best projects will explore links/framework not discussed by authors, and suggest future research directions
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Prerequisites Strong interest in graphics, rendering Computer graphics experience (4160) What if lacking prerequisites? Next slide Course will move quickly Covering recent and current active research Some material quite technical Assume some basic knowledge Many topics. Needn’t fully follow each one, but doing so will be most rewarding.
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If in doubt/Lack prerequisites Material is deep, not broad May be able to pick up background quickly Course requirements need you to really fully understand only one/two areas (topics) But if completely lost, won’t be much fun If in doubt, see if you can more or less follow some of papers after background reading Ultimately, your call
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Assignment this week E-mail me (ravir@cs) Name, e-mail, status (Senior, PhD etc.) Will you be taking course grades or P/F Background in graphics/any special comments Optional: Papers you’d like to present FCFS Paper presenters for next week [You (may) get a one-paper reduction in load] Hardware: Geometry Engine, Reality-Engine
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Questions?
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