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12 Cards in this Set
- Front
- Back
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Voxel Rendering |
Voxel (volume pixel) systems represent scenes using cubes Incredibly expensive to compute Comanche Maximum Overkill Primarily used in scientific pursuits (medical imaging) To reduce load a 2D height field image is used to represent terrain |
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Real Time Lighting |
Comples series of different techniques Can be represented by simply by Gouraud Shading or even flat shading Local point lights needed for this process Achieved by extending light calcs at the rendering stage to take multiple lighting positions/directions into account, though the colour of each pixel is also affected by texture Quake 1 - rockets, torches etc |
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Z buffering |
One of biggest problems is calculating which polygons appear in front and correctly displaying them Frame buffer = 1 being displayed, 1 being drawn to Can sort polygons in depth order and render from the back. If new pixel is closer = render, otherwise discard as it's obscured Super Mario 64 = geometrically complex worlds |
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Environment Mapping |
Cube maps - a photo of each image from one point for each side of the cube Object textured as if in centre of cube by projecting rays out from surface normals to gain reflection of environment Maths can be simplified to allow static reflections to be computed cheaply - not noticeable Gran Turismo - bodywork reflections |
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Complex Filtering |
Problem with texture map = images blocky when close or swim and shimmer when size reduced Caused by nearest neighbour filtering - doesn't take into account that centre of texels not where maths say they should be Complex Filtering takes into account adj. pixels Bi-Lin = surrounding square of 4 texels to interpolate colours required for each pixel Tri-Lin = adds MIP map levels Antistropic = takes surface orientation into account to improve details on surfaces oriented at oblique angles to the view plane |
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Anti Aliasing |
Removes jagged edges from polygons Multi Sample AA - takes samples at slightly diff positions inside each screen pixel (2-32) and average to get final colour Adaptive AA = comparing samples and stop when samples don't differ Tomb Raider |
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Real Time Shadows |
Invaluable for judging distance Renders environment from sun direction and stores info in Z buffer Creates shadow map from light source When player view rendered sees if pixel is in LoS of light source - if not draw without light on If light moves need update image = real time shadows Splinter Cell made use (hide in shadows) |
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Ambient Occlusion |
Realistic lighting = hard as light bounces everywhere AO crude way of simulating Computationally expensive = not real time Developer calcs for each object as they're created to be combined with real-time lighting when rendered Spray of light shot from each polygon in a hemisphere aligned to surface normal If ray doesn't intersect with other polygons in mesh surface made lighter as less light blocked Half-Life 2 on character models
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2D Vector graphics |
Based on Trig principles Shapes represented by points Pioneered by Space War! display by oscilloscope (beam used to display lines) 3D vectors used in Battlezone though only few tanks could be drawn despite having maths co-processor |
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Filled Polygons |
Came about with CRT CRT = raster based = millions of pixels Rendering = scan pixels on to screen Part of Bresenham line drawing algorithm which determine how pixels can represent straight lines I, Robot by Atari - 1983 |
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Scaled Sprites |
In 2D games sprites rendered at full size but 3D needs scaling relating to position of player Sprites placed at vectors - as image rendered pixels of sprite copied if player moves closer or skipped if moves away Space Harrier 1985 Still used today (Oblivion or tyre smoke PGR) Uses textured polygons aligned to square up to cameras view angle |
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Gouraud Shading |
Filled polygons let down by inherant angularity Gouraud blends gradients of colour, visually softening them Each vertex that defines polygon given colour - differences between adjacent vertices interpolated so shading changes smoothly across polygon Used alongside basic Real Time Lighting If surface normals of adjacent polys averaged can change them to vertex normals Makes lit surface appear smooth - TIE Fighter Vertex = vector with extra info on e.g. colour, surface normal |
