Computer graphics
2 likes449 views
Computer graphics involves two main pipelines - the geometry pipeline and imaging pipeline. The geometry pipeline involves modeling, transformations, and hidden surface elimination to represent 3D objects. The imaging pipeline involves rasterization, texture mapping, and composition to produce 2D images from the 3D representations. Key algorithms in computer graphics include rasterization to convert 3D objects to pixels, texture mapping to add surface detail, and shading models like Gouraud and Phong shading to add lighting effects. The course covers basic graphics concepts and definitions as well as the graphics pipeline through examples of processing a 3D scene.
Computer graphics
- 1. Graphics 1 Graphics & Graphical Programming
- 2. Graphics 2 Computer Graphics The experimentation of cathode rays is largely accredited to J.J. Thomson, an English physicist who, in his three famous experiments, was able to deflect cathode rays, a fundamental function of the modern CRT. The earliest version of the CRT was invented by the German physicist Ferdinand Braun in 1897 and is also known as the Braun tube
- 3. Graphics 3 Computer Graphics is about animation (films) Major driving force now
- 4. Graphics 4 Games are very important in Computer Graphics
- 5. Graphics 5 Medical Imaging is another driving force Much financial support Promotes linking of graphics with video, scans, etc.
- 6. Graphics 6 Computer Aided Design too
- 7. Graphics 7 Scientific Visualisation To view below and above our visual range
- 8. Graphics 8 Graphics Pipelines • Graphics processes generally execute sequentially • Typical ‘pipeline’ model • There are two ‘graphics’ pipelines – The Geometry or 3D pipeline – The Imaging or 2D pipeline
- 9. Graphics 9 Geometry Pipeline Animation/Interaction : time Modeling: shapes Shading: reflection and lighting Transformation: viewing Hidden Surface Elimination Imaging Pipeline
- 10. Graphics 10 Imaging Pipeline Rasterization and Sampling Texture Mapping Image Composition Intensity and Colour Quantization Geometry Framebuffer/Display Pipeline
- 11. Graphics 11 An example through the pipeline… The scene we are trying to represent: Images courtesy of Picture Inc.
- 12. Graphics 12 Wireframe model – Orthographic views
- 15. Graphics 15 Hidden Line Removal – add colour
- 16. Graphics 16 Constant Shading - Ambient
- 17. Graphics 17 Faceted Shading - Flat
- 18. Graphics 18 Gouraud shading, no specular highlights
- 19. Graphics 19 Specular highlights added
- 23. Graphics 23 Reflections, shadows & Bump mapping
- 24. Graphics 24 Computer Graphics A cathode ray tube is a vacuum tube which consists of one or more electron guns, possibly internal electrostatic deflection plates, and a phosphor target. An image is produced by controlling the intensity of each of the three electron beams, one for each additive primary color (red, green, and blue). In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is commonly used in oscilloscopes, a type of diagnostic instrument.
- 25. Graphics 25 Graphics Definitions • Point – a location in space, 2D or 3D – sometimes denotes one pixel • Line – straight path connecting two points – infinitesimal width, consistent density – beginning and end on points
- 26. Graphics 26 Graphics Definitions • Vertex – point in 3D • Edge – line in 3D connecting two vertices • Polygon/Face/Facet – arbitrary shape formed by connected vertices – fundamental unit of 3D computer graphics
- 27. Graphics 27 Graphics Definitions • Raster – derived from TV systems for a row of pixels – commonly referred to as a scanline – does influence algorithms – reducing memory requirements, parallelism, etc. – is the derivation of rasterization, scan-line algorithms
- 28. Graphics 28 Raster interlaced scanning
- 29. Graphics 29 Raster pros and cons •Disadvantages •Requires screen-sized memory array •Discrete spatial sampling (pixels) •Moire patterns result when shadow-mask and dot-pitch frequencies are mismatched •Convergence (varying angles of approach distance of e-beam across CRT face) •Limit on practical size (< 40 inches) •Spurious X-ray radiation •Occupies a large volume •Advantages •Allows solids to be displayed •Uses low-cost CRT H/W (TVs) •Whole Screen is constantly updated •Bright light-emitting display technology
- 30. Graphics 30 Summary • The course is about algorithms, not application packages • Graphics execution is a pipelined approach • Most of the steps introduced with an example • Basic definitions presented • Some support resources indicated • www.massey.ac.nz/~kahawick/159235 • Acknowledgements - Thanks to Eric McKenzie, Edinburgh, from whose Graphics Course some of these slides are based.