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What are 3D Graphics?

What are 3D Graphics?. 3D: Three-dimensional 3 Types of 3D Traditional 3D – 2D Graphics Interactive 3D – Dynamic Environment Immersive 3D – Sensory Overload. 3D Polygonal Model. A 3D model is a computer generated representation of a reality It doesn’t exist outside of the computer

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What are 3D Graphics?

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  1. What are 3D Graphics? • 3D: Three-dimensional • 3 Types of 3D • Traditional 3D – 2D Graphics • Interactive 3D – Dynamic Environment • Immersive 3D – Sensory Overload

  2. 3D Polygonal Model • A 3D model is a computer generated representation of a reality • It doesn’t exist outside of the computer • It is a creation of human beings • Frame Rate

  3. 3D Polygonal Model • A 3D model can therefore never exactly duplicate the physical world. • Producing 3D content is art in that it requires skill to generate and display • Components • Geometry • Appearance

  4. Components of a 3D Polygonal Model • Geometric Definition (shape) • Virtual Universe Coordinate System • Vertex (3D Coordinate Data) • Polygon (Area Boundary Data)

  5. Geometric Definition (Shape) • Virtual Universe Coordinate System • Infinite 3D Space X AxisY AxisZ Axis – (Z Depth) Origin = (0,0,0)

  6. Geometric Definition (Shape) • Vertex • Basic building block of a 3D model • Defines a three-dimensional location in relation to the virtual universe coordinate system of the model’s surface area. • Described by the coordinate system values (x, y, z)

  7. Geometric Definition (Shape) • Example (2 , 0, 1) x y z Vertex (X Axis) (Y Axis) (Z Axis)

  8. Geometric Definition (Shape) • Polygon • Defines the surface area of the 3D model • Defines the volume boundary of the 3D model • Constructed by connecting at least 3 vertices to form a defined surface area • Vertices can be shared by polygons within the same 3D model

  9. Geometric Definition (Shape) • Example (2 , 0, 1) Vertex (X Axis) (Y Axis) (0, 0, 0.4) (1, 0, 1) (Z Axis)

  10. Geometric Definition (Shape) • Example 0 - (2 , 0, 1) Vertex (X Axis) (Y Axis) 1 - (0, 0, 0.4) 2 - (1, 0, 1) (Z Axis)

  11. Raw Polygon Data Vertices 2 0 1 1 0 1 0 0 0.4 Polygons 0 2 1 Forward Facing Polygon 2 0 1 Counter Clockwise Order

  12. Virtual Reality Modeling Language VRML97 • Same Polygon in VRML97 Format • #VRML V2.0 utf8 • Shape { • appearance Appearance { • material Material { • } • } • geometry IndexedFaceSet { • coord Coordinate { • point [ • 2 0 1 • 1 0 1 • 0 0 0.4 • ] • } • coordIndex [ • 0, 2, 1 • ] • } • }

  13. Virtual Reality Modeling Language VRML97 • #VRML V2.0 utf8 • Shape { • appearance Appearance { • material Material{ • } • } • geometry IndexedFaceSet { • coord Coordinate { • point [ • 0 0 0 • 1 0 0 • 1 1 0 • 0 1 0 • 0 0 1 • 1 0 1 • 1 1 1 • 0 1 1 • ] • } • coordIndex [ • 3, 2, 1, 0, -1, • 0, 4, 7, 3, -1, • 3, 7, 6, 2, -1, • 3, 0, 4, 7, -1, • 4, 5, 6, 7, -1, • 5, 1, 2, 6, -1, • 0, 1, 5, 4 • ] • } • }

  14. Components of a 3D Polygonal Model • Appearance Definition (color) • Normals of Light Reflection • Methods of Color Display • Global Color • Color-Per-Vertex • Texture Mapping

  15. Appearance Definition (color) • Normal • A vector (direction) that describes how light will reflect from the surface of the model • A normal can be set for each vertex and polygon within a 3D model • If described for one, must be described for all • Affects smoothness, highlights, and shadows

  16. Methods of Color Display • Global Color Properties of a Model • RGB color values • R 255, G 255, B 255 = White • R 255, G 0, B 0 = Bright Red • R 0, G 0, B 0 = Black • Diffuse Color – material color • Specular Color – highight color • Emissive Color – glowing color • Shininess – amount of light • Transparency – see through • All are affected by color of light emitted from light objects in the virtual universe

  17. Methods of Color Display • Color-Per-Vertex (cpv) • Are Diffuse RGB color values • Connected to a vertex • Color of vertex blends with near by vertices • Vertices without cpv assigned global diffuse color

  18. Methods of Color Display • Texture Mapping • All 3D vertices are given coordinates in a positive 1x1 2D grid (UV Coordinates) • UV Coordinates are “mapped” onto a 2D graphici.e. a GIF, JPEG, or PNG file. • Colors from the 2D graphic appear on the model as assigned by the UV Coordinate grid

  19. 3D Non-Contact Laser Digitizers • “Paints” the object with a line of laser light • Received by the digitizer’s camera lens • Combination of mirror angle and laser intensity produces vertex information • Noise – distance error

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