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Specifying an Arbitrary 3D View

Specifying an Arbitrary 3D View. Creation of a 3D View. Mapping a 3D view onto a 2D screen requires:. specifying a projection model. specifying viewing parameters. specifying viewing parameters. 3d clipping. projection and display. Creation of a 3D View.

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Specifying an Arbitrary 3D View

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  1. Specifying an Arbitrary 3D View

  2. Creation of a 3D View Mapping a 3D view onto a 2D screen requires: • specifying a projection model • specifying viewing parameters • specifying viewing parameters • 3d clipping • projection and display

  3. Creation of a 3D View View Reference Point (VRP) - a point on the view plane View Plane Normal (VPN) - a vector normal to the view plane View-Up Vector (VUP) - defines the v axis direction. (indicates which way is up.)

  4. v PROJECTION PLANE VIEW PLANE View Reference Point VUP VRP View-Up Vector VPN u View Plane Normal n Creation of a 3D View

  5. Creation of a 3D View Coordinate Systems: Viewing Reference Coordinate System World Coordinate System

  6. Creation of a 3D View Viewing Reference Coordinate Systemorigin - the VRPn axis - the VPNv axis - coincident with the projection of the VUP onto the view planeu axis - perpendicular to n and v axes, and defined such that u, v, and n form a right-handed coordinate system.

  7. y y v y y y y VIEW PLANE Viewing Reference (Camera) Coordinate System y v z z x x z z u x x z z z n u x World (Object) Coordinate System x n x Creation of a 3D View

  8. v VIEW PLANE (Umax,Vmax) VRP (Umin,Vmin) VPN u n CW Creation of a 3D View

  9. Creation of a 3D View Viewing Reference Coordinate SystemThe center and direction of projection are defined by : - a projection reference point PRP - the projection type (perspective/parallel)

  10. v VIEW PLANE VRP VPN u n PRP CW Projection Reference Point - defines direction of projection Creation of a 3D View: parallel

  11. v VIEW PLANE VRP VPN u n PRP Projection Reference Point = center of projection Creation of a 3D View: perspective

  12. Creation of a 3D View Mapping a 3D view onto a 2D screen requires: • specifying a projection model • specifying viewing parameters • 3D clipping • 3D clipping • projection and display

  13. Creation of a 3D View View Volume:defines thebounds of the world coordinate system that is to be clipped and projected onto the view plane.

  14. v VIEW PLANE VRP VPN u n PRP CW Projection Reference Point - defines direction of projection Creation of a 3D View: parallel

  15. BACK CLIPPING PLANE v VIEW PLANE FRONT CLIPPING PLANE VRP VPN u n CW Creation of a 3D View: parallel

  16. v VIEW PLANE VRP VPN u n PRP Projection Reference Point = center of projection Creation of a 3D View: perspective

  17. BACK CLIPPING PLANE v VIEW PLANE FRONT CLIPPING PLANE VRP VPN u n PRP Creation of a 3D View: perspective

  18. Creation of a 3D View 3D Clipping for the parallel view volume:extension of the 2D Cohen-Sutherland clipping algorithm 6 bit outcodes: 100000 point is above view volume y > 1 010000 point is below view volume y < -1 001000 point is right of view volume x > 1 000100 point is left of view volume x < -1 000010 point is behind view volume z < -1 000001 point is in front of view volume z > 1

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