CSC 220 3D Computer Graphics Fall 2003

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CSC 220 3D Computer Graphics Fall 2003

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Graphics Hardware Text Mode – Characters (2K bytes) Graphics Modes – Pixels (a large number of bytes) x-y organize framework Raster Scan with Frame Buffer (associating ) Vector Scan with Display List

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Color for Computer Graphics Red, Green, Blue phosphors and shadow veil VGA – 640 x 480 with 16 hues VGA – 320 x 200 with 256 hues, utilizing the Color LookUp Table (CLUT) – 8 bits/pixel is 256 hues at one time, yet 262,144 hues in palette SVGA with True Color – 800 x (at least 600), utilizing 24 bits/pixel – a great many hues at the same time

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Graphics Software BASIC is a special case API's, or libraries Borland Graphical Interface (BGI) Graphical Kernel System (GKS) OpenGL …

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Graphics File Formats GIF JPEG BMP TIFF Targa …

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The Graphics Pipeline Modeling – geometry of a question Viewing – how the protest seems shrouded surfaces engineered camera Rendering – authenticity and all the more lighting shading surfaces shadows

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Modeling Techniques Polygons (Triangles) Splines (NURBS) Constructive Solid Geometry (CSG) Fractals …

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Teddy – a Modeling Applet Simple and brisk For harsh models in a split second Spherical topology Operations creation expulsion cutting bowing

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TERA An apparatus for visual education Can show 500,000 mixes of pictures rendered by different strategies Can be utilized as a part of two ways investigate rendering impacts individual test rendering impacts Contains POV-Ray records likewise

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Some Visual Cues Visibility Shadows Reflections Refraction

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Surface Algorithms Visibility wireframe – vagueness concealed lines/surfaces Rendering procedures (2 of numerous) z-cradle beam following

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Some Minimal Mathematics 3D facilitates – x,y,z as LHS Vectors – bearing and extent Normal vector to a surface Culling back appearances

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The Z-cushion Method Along with casing support have a z-support: Frame support holds shading esteem for the pixel Z-support holds z esteem for the pixel area Scan every surface in progression. In the event that z esteem for this area on this surface is not as much as esteem in z-cradle, supplant shading in edge support and overhaul esteem in z-cushion Most regular rendering strategy, frequently with exceptional equipment

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POV-Ray No displaying, utilizes Scene Description Language (SDL) Does survey and rendering No books in print, yet brilliant on-line documentation Exercises from TERA content render gold.pov , p.9 render room.pov , p.20 update camera introduction of room , pp.21,22

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Specifying an Image in SDL Objects Simple shapes CSG objects Advanced shapes Transformations Texture Camera Lighting

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Simple Shapes Spheres Boxes Cones Cylinders Planes

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Constructive Solid Geometry Union Intersection Difference Merge

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Transformation of Coordinates Affine changes interpretation scaling pivot Composition of relative changes Properties of relative changes straight lines remain straight parallel lines remain parallel edges don't remain settled, aside from inflexible changes (no scaling)

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Z-Buffer Shading Constant Shading – shading processed once for whole protest Faceted Shading – shading figured once for every polygon Gouraud Shading – shading registered utilizing vertex typical, then twofold interjection of shading qualities in the polygon Phong Shading – twofold insertion of vertex normals, then shading esteem registered for each added vector esteem in the polygon

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Lights in POV-Ray Point lights Spotlights range falloff snugness versatile jitter Cylinder lights (same parameters as spotlight) Area lights Ambient lighting

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Reflected Light When light strikes a surface, a few hues are assimilated, and we see the hues that are reflected. We manage three sorts of reflections: surrounding reflected light diffuse reflected light specular reflected light ( Phong brightening) Computing the reflected qualities requires that vectors must be increased.

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Ray Tracer Shading Multiple reflections Transparency Refraction Shadows

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2D Texture Mapping Map Types planar – typical parallel to X, Y, or Z barrel shaped – pivot around X, Y, or Z circular – turn around X, Y, or Z box – ordinary parallel to X, Y, or Z Problems posts mutilation associating Bilateral symmetry and planar maps

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3D Texture Mapping Procedural – surface is capacity f(x,y,z) Common surfaces are stripes, rings, inclines Noise for reasonable impacts plentifulness recurrence utilization of higher request terms erraticism, tilt, and contort Texture works in POV-Ray for glass, metal, stone, and wood

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Viewing – the Synthetic Camera World Coordinates (WC) – x,y,z r is area of camera in WC The View Plane – U,V,N N is the place camera is looking V is into heading, orthogonal to N U is 3 rd hub, orthogonal to both N and V

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Light and its Perception In depicting the impacts of light we should consider both material science and physiology. The wavelength of unmistakable light shifts from 400 nanometers (violet) to 700 nanometers (red). In depicting the nature of light, we require three parameters: tint – the predominant wavelength power (material science) or splendor (physiology) immersion – the virtue of the tone

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The Human Eye The eye has bars that are extremely delicate to light versus dim (around 1 photon), and cones that are less touchy to level (around 5 photons) yet can recognize hues. There are cones delicate to blue, to green, and to red. They are all in the fovea (1/4 mm), and are the premise of the tristimulus hypothesis of vision . Light which is a blend of red and green looks generally as yellow as does immaculate yellow light! The human visual framework can't recognize hints and sounds as does the human sound-related framework.

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The Color Cubes The primaries for added substance (transmitted) shading in PC representation are red, green, and blue, yielding the RGB shading 3D shape. red + green = yellow red + blue = red green + blue = cyan The primaries for subtractive (reflected) shading are cyan, fuchsia, and yellow, yielding the CMY shading solid shape. cyan ink ingests red ink assimilates green yellow ink retains blue

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The HSV Color System It is hard to foresee what a given blend of RGB levels will resemble. For such a reason, it is simpler to utilize the HSV organize framework based upon Hue, Saturation, and Value. This maps to a cone or a six-sided pyramid: Hue is the rakish area as an afterthought divider Saturation is the relative separation from the inside line to the shading point (immaculateness) Value is the stature in the modified cone These can without much of a stretch be considered in more characteristic terms, for example, tints, shades, and tones.

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Halftoning When there are a set number of shading levels accessible in the yield, we can exchange spatial determination for shading determination. Along these lines, there might be only 2 shading levels (e.g. dark or white). Take 'super-pixels' of size 2x2 or 3x3. Inside a 2x2 piece, there are 4 singular pixels that may or not be lit, for 5 levels of total force in that super-pixel. To the eye, the expanded shading degree is certainly justified regardless of the misfortune in spatial determination.

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Some Advanced Shapes Blobs for knotty items Splines to fit to control focuses estimation – Bezier bends introduction – numerous sorts of splines piecewise polynomial areas (cubics) smoothness, or congruity NURBS – N on U niform R ational B S plines

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NURBS Non-uniform reasonable B-splines non-uniform – separating of control focuses sound – a remainder (proportion) of polynomials additionally ties where wrinkles are coveted NURBS are useful for demonstrating bends Just as imperative properties are kept up with relative changes, so are NURBS kept up under projective changes – so just control focuses need be changed. NURBS can display conic segments precisely!

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The Rhino Interface Rhino is a demonstrating instrument – has primitive shading and rendering capacity 3 Orthographic Viewports beat, front, right perspectives are default base, back, left perspectives are additionally conceivable 1 Perspective Viewport 2 Toolbars, with flyouts

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Viewing in Rhino Parallel or viewpoint projection (each viewport) Panning Rotating Zooming zoom dynamic zoom degrees zoom window zoom chose

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Drawing Lines Line portions versus polylines Coordinate frameworks supreme cartesian 3,4 relative cartesian r3,4 total polar 5<60 relative polar r5<60

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Modeling Aids Snap to matrix Ortho Object Snaps Layers Constraints separate limitation 5 edge requirement <60

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Editing Objects Split and Trim Join and Explode Filet Chamfer Transforms scale pivot reflect

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Rhino Geometry Points Curves Surfaces Polysurfaces – mixed surfaces Solids – shut polysurfaces

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Creating Curves Free-shape control focuses – Bezier bends (for guess) introduce focuses – spline bends (for interjection) portray Conic segments Polygons

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Creating Surfaces From focuses From bends Extrusion Lofting Revolves Rail clears

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Creating Solids Box Sphere Cylinder Tube Cone Ellipsoid Torus

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Technical Side of Animation The Storyboard Keyframes Inbetween outlines for shape ( transforming ) for movement Motion catch Physical displaying

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Artistic Side of Animation Stretch and Squash Timing Anticipation Staging Slow In and Out Emotion