Joshua Smith and Garrick Solberg CSS 552 Topics in Rendering 3D Anaglyph stereoscopic rendering
What is Stereoscopy? • Adds “depth” to a two dimensional image via stereopsis • Two planar images are rendered, one for each eye • Through some method, such as color filters, the brain is tricked into believing it is seeing one image, resulting in the perception of depth
Human Depth Vision • Our eyes see two slightly different views into the world • Ex: look at an object and close one eye, then switch • The eyes shift and rotate these views onto a point of convergence. Objects closer or farther away than this point creates parallax.
Anaglyph Projection • Image corresponding to the right eye projection is displayed on one color (blue, green, or cyan) • Image corresponding to the left eye is displayed in red • Stereo glasses filter out the image an eye is not supposed to see by matching the color
Measuring Positive Parallax PQ/LR = VQ/VR VQ/VR = VM/RN = (w – C)/w = 1 – C/w p = D(1 – C/w)
Measuring Negative Parallax PQ/LR = QV/VR = QV/(QR-QV) = (QV/QR)/(1 – (QV/QR)) QV/QR = VM/RN = (C-w)/C = 1 – w/C PQ/LR = p/D = (1-w/C)/(w/C) = C/w -1 p = -D(1 – C/w)
FrustrumCalculationDiagram top = Dnear * tan(θFOVy/2) bottom = -top a = raspect * Ctan(θFOVy/2)
Special Considerations Eye (camera) separation Convergence distance Camera positions High contrast
Eye Separation Human eyes are 6.5cm apart Less will loose information More will create greater spatial view but harder on eyes Images from : http://www.cafedownloads.com/reviews/r13/3dstereo.html
Convergence Scale of 1/30 between observer and closes object. Based off of the space between eyes Equivalent to ≈ 2 meters from a window Viewing area is both the window and the horizon.
Convergence – Hyper-Stereo Closer than 1/30th Makes the image seem like a model Image from: http://www.flickriver.com/photos/ur4chun8/3529791785/
Convergence Hypo-Stereo Farther than 1/30th Enlarges the image Image from http://www.flickr.com/photos/adcnj3d/5414231379/in/photostream/
High Contrast • Creates "ghosts" where anaglyphs are too close/strong red and cyan spots • Areas with lots of red or green/blue areas will have little to no information for the corresponding eye
Types of Images • Time sequential • Shutters close to match to left and right images on screen • Polarized • Each lens will block light polarized in the opposite direction with two images superimposed • Anaglyph • Glasses with two different colored lenses that corresponds to two images superimposed
Types of Anaglyphs Type Colors Visible • Red – Green • Red – Blue • Red – Cyan • Magenta – Cyan • Anachrome • Mirachrome • Trioscopic • Inficolor • ColorCode 3D • Monochrome • Monochrome • Bad reds good greens • Better than Red – Cyan • Bad reds • Bad reds • Better colors • Fuller colors • Almost full color Cutesy of Wikipedia
Limitations with Anaglyphs • Image quality • High contract colors • Limited on what colors are displayed by lens type