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Comp 767: Propelled Points in Representation: Picture Based Rendering. View Transforming by Steven M. Seitz Charles R. Dyer. Irwin Chiu Hau Software engineering McGill College Winter 2004. Comp 767: Propelled Subjects in Representation: Picture Based Rendering. Review. Mona Lisa view transforms

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Comp 767: Advanced Topics in Graphics: Image-Based Rendering View Morphing by Steven M. Seitz Charles R. Dyer Irwin Chiu Hau Computer Science McGill University Winter 2004

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Overview Mona Lisa see transforms Source: http://www.cs.washington.edu/homes/seitz/vmorph/vmorph.htm What is view transforming? How to do see transforming? Comes about Conclusion

Comp 767: Advanced Topics in Graphics: Image-Based Rendering View Morphing Virtual Cameras Source: View Morphing; Steven M. Seitz, Charles R. Dyer What is view transforming? What is it? Why do we think about it? Where do we see them? Picture Morphing versus View interjection versus View Morphing

Comp 767: Advanced Topics in Graphics: Image-Based Rendering View Morphing: Key Idea Beier-Neely transform is NOT shape-safeguarding! bends un-characteristic A Shape-Distorting Morph Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering View Morphing: Key Idea View transforming utilizes 3D shape saving transform! no twists common A transform is 3D shape protecting if the aftereffects of two unique perspectives speak to new perspectives of a similar question View transforming fixes these middle of the road steps! A Shape-Distorting Morph Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Why do we give it a second thought? See transforming is proficient Produces new perspectives without 3D demonstrating Taking extra photographs View transforming makes amazing impacts Camera movement Image transforming trueSpace Source: www.caligari.com

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Image Morphing versus View introduction versus View Morphing View Morphing is an expansion to Image Morphing (Beier and Neely, 1992) Produces physically conceivable new perspectives of a scene View Morphing (Seitz and Dyer, 1996) is a change outline Interpolation (Chen and Williams, 1993) Addresses non-inflexible changes issues Does not require profundity values Creates practical picture moves

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Overview Mona Lisa see transforms Source: http://www.cs.washington.edu/homes/seitz/vmorph/vmorph.htm What is view transforming? How to do see transforming? Comes about Conclusion

Comp 767: Advanced Topics in Graphics: Image-Based Rendering How to do View Morphing? See transforming in three stages Prewarp two pictures Compute a transform between the prewarped pictures Postwarp each in the middle of pictures created by the transform View Morphing Procedure Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering How to do View Morphing? See transforming in three stages Prewarp two pictures Compute a transform between the prewarped pictures Postwarp each in the middle of pictures created by the transform View transforming in 1 stages: Assume parallel perspectives! Register a transform between the parallel pictures

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Parallel Views Basic Theory picture point p 0 = (x 0 ,y 0 ) scene point P = (X,Y,Z) p 0 = Π 0 P where Π 0 is a projection framework picture point p 1 = (x 1 ,y 1 ) scene point P = (X,Y,Z) p 1 = Π 1 P where Π 1 is a projection network Morphing Parallel Views Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Parallel Views Basic Theory picture point p = (x,y) scene point P = (X,Y,Z) p = Π P where Π is a homogenous projection network Π = [ H | - HC] H: position and introduction of picture plane C: euclidean position of the camera Morphing Parallel Views Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Parallel Views Mathematics for View Interpolation Πs: Linear insertion of Π 0 and Π 1 Πs = (1 – s) Π 0 + s Π 1 s = [0,1] Cs = (sCx, sCy, 0) fs = (1 – f) f 0 + s f 1 f : central lengh C : focal point of a camera

View Interpolation versus View Morphing Comp 767: Advanced Topics in Graphics: Image-Based Rendering View Interpolation Recap View Interpolation Source: 3D Games by Alan Watt and Fabio Policarpo Morphing Parallel Views Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering How to do View Morphing? See transforming in three stages Prewarp two pictures Compute a transform between the prewarped pictures Postwarp each in the middle of pictures delivered by the transform View transforming in 1 stages: Assume parallel perspectives! Register a transform between the parallel pictures

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Non-Parallel Views The General Case This is the place the 3-Step Algorithm becomes possibly the most important factor Prewarping: I 0 to Î 0 and I 1 to Î 1 Morphing: Î 0 and Î 1 into Î s Postwarping: Î s into I s Morphing in Three Steps Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Non-Parallel Views Mathematics for Image Reprojection ^ ĤH - 1 p = p H and Ĥ are 3x3 networks that speak to the position and the introduction of their picture planes The subsequent 3x3 lattice, ĤH - 1 is a projective change that reprojects the picture plane I into Î Morphing in Three Steps Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Limitations Singular Views can\'t be reprojected to shape parallel perspectives Singular designs are settings where one of the camera dwells in the field of perspective of another camera Still works, only sort of thoughtfully hacky Singular view Source: Steven M. Seitz, Charles R. Dyer Parallel view Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Traditional Problems Change in perceivability makes Folds Occurs when a noticeable zone gets to be distinctly blocked Holes Occurs when an impeded zone gets to be distinctly unmistakable Area Point Fold Source: Irwin Chiu Hau Penumbra, umbra and opening areas Source: Chen and Williams

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Producing The Morph We have discussed hypothesis behind calculation How to extend/unproject pictures to parallel planes How to twist between parallel planes Theoretical issues Now, how about we do a genuine View Dependent Morph!

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Producing The Morph We require: Two pictures I 0 and I 1 Two point of view projection networks Π 0 and Π 1 Correspondence between pixels Note that a grouping of projection grids Π s is required to control the whole activity, yet Π s can be processed naturally on the off chance that we know H s .

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Controlling The Morph H s can be acquired in a roundabout way by building up requirements Recall H s is position and introduction of picture plane One route is to indicate four control focuses Note: Control focuses certainly decide the postwarping change Four control focuses frame the red jumping box to decide the postwarping stage Yellow lines are set of components to decide the prewarping stage View Morphing Procedure Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering View Morphing sans Prewarping is a bit much for: Objects that aren\'t firmly related Prewarping is less viable Computation is shaky Images that are approx. orthographic (eg. fax) However, postwarping ought not be forgotten to: Reduce picture plane distorsions

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Overview Mona Lisa see transforms Source: http://www.cs.washington.edu/homes/seitz/vmorph/vmorph.htm What is view transforming? How to do see transforming? Comes about Conclusion

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Results Facial view transforms Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Results Facial view transforms Source: http://www.cs.washington.edu/homes/seitz/vmorph/vmorph.htm

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Results Mona Lisa see transforms Source: http://www.cs.washington.edu/homes/seitz/vmorph/vmorph.htm

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Results Image Morphing versus View Morphing Image Morphing versus View Morphing Source: Steven M. Seitz, Charles R. Dyer

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Conclusions Things to recall View Morphing Powerful augmentation to picture transforming Produces new perspectives of a scene 3D shape safeguarding

Comp 767: Advanced Topics in Graphics: Image-Based Rendering References View Morphing - Seitz and Dyer, 1996 View Interpolation - Chen and Williams, 1993 Image Morphing - Beier and Neely, 1992 3D Games: Realtime rendering and Sofware Technology -Alan Watt and Fabio Policarpo

Comp 767: Advanced Topics in Graphics: Image-Based Rendering Questions?