Úvod do po ítač ovej grafiky - SCCGDigital Image Processing (Low Level) • The negative of an...
Transcript of Úvod do po ítač ovej grafiky - SCCGDigital Image Processing (Low Level) • The negative of an...
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Úvod do počítačovej grafiky bez geometrie: Image-based Rendering
Andrej FERKO
Comenius University Bratislava
22. marca 2018, FMFI UK
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Motivation
• Time, costs...
• human visual system
• field of view
• of around 135x200 degrees,
• but a typical camera
• only 35 x 50 degrees...
• Plenoptic modeling... 1995
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Plenoptic modeling
• Plenoptic modeling... Bishop & McMillan 1995
• “Image-based rendering is a powerful new approach for generating real-time photorealistic computer graphics... convincing animations without an explicit geometric representation.”
• Tools: Dersch, Hugin, PTGui...
• AutoStitch - Brown-Lowe 2003 • http://matthewalunbrown.com/autostitch/autostitch.html
• 7D Plenoptic Function >> 2D panorama
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Plenoptic function [BM95]
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Sea of Images 2002
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Photosynth 2006-10
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Autostitch
• [BL03]
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Process
• [BL03]
• http://matthewalunbrown.com/autostitch/autostitch.html
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Principles of geometric analysis and synthesis of a mathematic model
• princíp kontinuity • (nepreryvnost: spojitost, koherencia)
• princíp zhody • (sootvetstvije: dodržiavanie, consistency, conformity)
• princíp kompatibility • (sovmestimost: zlucitelnost)
• Baganyan, GA. 1985. Mašinnaja grafika v upravľenii. Jerevan: Ajastan.
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History before computers
• Panorama of 'Old Edinburgh' by Robert Barker
• Barker's patent for painting panoramas expired in 1801, which meant the 360-degree images could be produced by rival artists
• Tools: Dersch, Hugin, PTGui...
• AutoStitch - Brown-Lowe 2003 • http://matthewalunbrown.com/autostitch/autostitch.html
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SIGGRAPH Slide Show
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Model >> Picture, context
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• https://www.wiley.com/legacy/compbooks/vrml2sbk/ch02/02fig01.htm
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Virtual Heart of Central Europe, Culture 2000
• Awarded by EuroPrix Quality Seal
www.VHCE.info • 330 kEUR, 150 kEUR from EC, Slovak Prix
• follow-up 2005-2006 (SK, SI, PL, CZ), submitted, 256 kEUR, rejected
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Compare Reality - Synthesis
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Photography ~ computer
graphics • Controlled Error: Model, Algorithm… Solution
• ISO: Computer graphics: methods & techniques for
construction, manipulation, storage and displaying
pictures using computer.
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Compare Workflow (PTGui)
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Compare Workflow (PTGui)
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Image-based rendering motivates Image Processing...CV
Learning OpenCV: Computer vision with the OpenCV … - Bradski Citované 5742-krát
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SK: [Ru] & dip.sccg.sk
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dip.sccg.sk
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From digital image (Ruzicky)
to IBR (OpenCV pipeline)
http://www.sccg.sk/~ferko/PGASO2012-bookmarks.pdf
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Image-based rendering (e.g. OpenCV pipeline)
Intro Reading: e.g. https://en.wikipedia.org/wiki/Image_stitching
Image registration is the process of transforming different sets of data into one coordinate system.
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Image Registration
Image registration, transforming different sets of data into one coordinate system. e.g. Diffeomorphism, an isomorphism of smooth manifolds, an invertible function that maps one differentiable manifold to another such that both the function and its inverse are smooth
Why? to see things previously impossible to see, e.g. the distant Alps https://en.wikipedia.org/wiki/Image_registration
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History 2, Bratislava
Veduta, malovana rovinna panorama a dvojpohladova vizualizacia, VrBa.
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History 3… Street View 2007
Aspen Movie Map, MBR >> IBR, 20 peta 2012
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Digital Image
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Digital Image Properties
[Ru], Wi, [Kalra]
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Digital Image >> Model
• Model>Picture: SetPixel • Model>Picture: GKS 6, polyline, polymarker, fill area, text, cell array, NUB (GDP)
• Model>Picture: SVG 14, path, basic shapes, text... or feature sets
• Image>Model: e.g. Harris Corner Detector, interaction
• Image>Model: e.g. Harris Edge Detector, snake... CV (OCR etc.)
• Image Registration • Mathematic Morphology
• Image Correspondence • Image Segmentation
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Digital Image >> Model
• Model>Picture: SetPixel • Model>Picture: GKS 6, polyline, polymarker, fill area, text, cell array, NUB (GDP)
• Model>Picture: SVG 14, path, basic shapes, text... or feature sets
• Image>Model: e.g. Harris Corner Detector, interaction
• Image>Model: e.g. Harris Edge Detector, snake... CV (OCR etc.)
• Image Registration • Mathematic Morphology
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Digital Image Processing (Low Level)
• The negative of an image with gray levels in the range [0,255], s = 255 – r
• Contrast stretching by increasing the dynamic range [Benesova]
• The histogram of a digital image with gray levels in the range [0, L-1] is a discrete function h (rk) = nk, where rk is the k-th gray level and nk is the number of pixels in the image having gray level rk [Benesova] >> EQUALIZATION
• Image averaging
• Image subtraction
• Smoothing/sharpening
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Histogram Equalization
https://en.wikipedia.org/wiki/Histogram_equalization
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Digital Image Transformations
• Translation, rotation, scale, symmetry, skew >> dip.sccg.sk
• Pixel approximation: nearest neighbour (1 pixel), bilinear interpolation (4 pixels), bicubic interpolation (9 pixels)
https://en.wikipedia.org/wiki/Bicubic_interpolation#/media/File:Comparison_of_1D_and_2D_interpolation.svg
• Fourier transform >> dip.sccg.sk, Ruzicky, Sikudova
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Fourier Transform Visually
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Úvod do počítačovej grafiky bez geometrie: Image-based Rendering
Andrej FERKO
Comenius University Bratislava
21. marca 2018, FMFI UK