o Basic signal processing o Filtering, resampling, warping,... Rendering o Polygon rendering pipeline o Ray tracing Modeling

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1 Background COS526: Advanced Computer Graphics Tom Funkhouser Fall 2010 Image Processing o Basic signal processing o Filtering, resampling, warping,... Rendering o Polygon rendering pipeline o Ray tracing o Basic 3D object representations o Polygonal meshes Slides from Durand, Efros, Finkelstein, Freeman, Lazebnik, Rusinkiewicz, Seitz Background Background Image Processing o Basic signal processing o Filtering, resampling, warping,... Image Processing o Basic signal processing o Filtering, resampling, warping,... 3D Geometric Primitives Transformation Rendering o Polygon rendering pipeline o OpenGL o Basic 3D object representations o Polygonal meshes Input signal Sampled signal Rendering o Polygon rendering pipeline o Ray tracing o Basic 3D object representations o Polygonal meshes Lighting Viewing Transformation Projection Transformation Clipping Scan Conversion Reconstructed signal Image Background Image Processing o Basic signal processing o Filtering, resampling, warping,... Rendering o Polygon rendering pipeline o Ray tracing o Basic 3D object representations o Polygonal meshes 1

2 Sorkine Praun Jensen Coursework 4 Short written exercises 3 Programming assignments Final project 2

3 What is? Definition 1: the use of photographic imagery to create content for computer graphics Traditional Computer Graphics 3D geometry projection simulation physics State of the Art The richness of our everyday world Amazingly real but sterile, lifeless, futuristic Pavia, Italy Beauty in complexity Which parts are hard to model? Blue Mountains, Australia 3

4 People Faces / Hair On the Tube, London Photo by Joaquin Rosales Gomez Final Fantasy Final Fantasy Urban Scenes Nature River Cherwell, Oxford Photo of LA Virtual LA (SGI) Camera controls: o Viewpoint o Lens o Shutter speed o Aperture o Sensor Pin-hole camera: Slide by Freeman and Durand From Photography, London et al. 4

5 Pin-hole size? Pin-hole size? o Smaller produces sharper image (up to limits of diffraction) o Larger lets in more light From Photography, London et al. From Wandell Lenses f Lenses D f D = 1 D D f Slide by Freeman and Durand Slide by Freeman and Durand Lenses + More light + Sharp - at one depth Effect of different focal lengths 24mm 50mm 135mm From Photography, London et al. 5

6 Limited resolution Single depth of focus Bad color / no color Limited dynamic range Single viewpoint Static scene NFL 6

7 Blur, camera shake, noise, damage Unfortunate expressions Unwanted objects The Realism Spectrum Computer Graphics Computational Photography Photography Realism Manipulation Ease of capture + easy to manipulate objects/viewpoint - hard to acquire/create - hard to make realistic - hard to manipulate objects/viewpoint + easy to acquire + instantly realistic What is? Definition 1: the use of photographic imagery to create graphics content Example: high-dynamic range Definition 2: The use of computational techniques to overcome limitations of traditional photography Debevec 7

8 Example: deblurring Example: super-resolution Fergus Hertzmann Example: creating panorama Example: gigapixel images Kopf Example: color harmonization Example: background replacement Cohen-Or 8

9 Example: image completion Example: image completion Preliminary results Sun et by al. Sashi (2005) Kumar Penta Sun Efros Example: tour into the picture Example: photo tourism Horry Snavely Next Time Texture synthesis 9