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Virtual reality

Virtual reality. Tasks. 3D digital model from planes. Office work. Solid modeling. 3D digital model of existing objects. Field observations. Photogrammetry. Solid modeling. From 2D elements. Cross section and a vector (sweeping).

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Virtual reality

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  1. Virtual reality

  2. Tasks 3D digital model from planes Office work Solid modeling 3D digital model of existing objects Field observations Photogrammetry

  3. Solid modeling From 2D elements Cross section and a vector (sweeping) Cross section and a axis of rotation(body of revolution) Body representation methods Boundary representation (BR) Constructive Solid Geometry (CSG) Voxels

  4. Creating 3D world Difficulties using 2D tools CAD or special software (3D Studio) Constructing from views (front view, top view, side view) Different views at the same time (perspective, front, top, views) Primitive objects (box, sphere, cone, cylinder, etc.) 3D faces, surfaces (NURBS, Non Uniform Rational B-Splines) Materials, texture maps, material libraries

  5. NURBS Non Uniform Rational B-Splines

  6. Vizualization Wireframe Hidden lines, hidden surfaces Z-buffer algorithm Rendering, light sources, materials ray traceing reflection, transparency

  7. photo photo II photo x’ x’ x” f Constantscale factor t x x object object Digital model from photos Scale factor changing

  8. Projective transformation Perspective projection between two non parallel planes,collinarity condition Form with homogeneous coordinatas Two linear equation for each point Homogeneous coordinates

  9. Projective transformation

  10. Spatial solution (3D) Two photos from different point of views Relative orientation, minimum. 6 points onboth photos, reconstructing the relative position Absolute orientation, minimum 3 known pointsin the used co-ordinate system Analytical solution (mathematical projection, adjustment) Connecting several photos to the model

  11. Measuring control points • Intersection • Polar points (Direct reflex) • Laser scanner • Robotic instruments

  12. VRML Virtual Reality Markup Language Free viewers Cortona VRML Client http://www.parallelgraphics.com/products/cortona/ Cosmo Player VRML 1 1995 (Silicon Graphics' Open Inventor ASCII format) VRML 2 1996 VRML 97 (ISO/IEC-14772-1:1997) #VRML V2.0 utf8 Shape { geometry Box { size 1 1 1 } } .wrl files (world) Simple text files, platform independent

  13. VRML features • Description of 3D spaces (creation?) • Moving objects, animation • Hyperlinks (html, wrl) • Playing sound and video • User interactivity • Programmable (java or javascript) VRML cont. Application areas Visual design, cities, flats, etc. Advertisements, games, artist Education (geometry) Tourism (virtual cities) Simulation, mechanical engineering Vrml.html

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