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11. Wireframe Perspective Display

ME 521 Computer Aided Design. 11. Wireframe Perspective Display. Dr . Ahmet Zafer Şenalp e-mail: azsenalp@gyte.edu.tr Makine Mühendisliği Bölümü Gebze Yüksek Teknoloji Enstitüsü. 11. Wireframe Perspective Display. The Eye Coordinate Sysytem :.

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11. Wireframe Perspective Display

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  1. ME 521 ComputerAidedDesign 11. WireframePerspectiveDisplay Dr. Ahmet Zafer Şenalpe-mail: azsenalp@gyte.edu.tr Makine Mühendisliği Bölümü Gebze Yüksek Teknoloji Enstitüsü

  2. 11. WireframePerspectiveDisplay TheEyeCoordinateSysytem: To calculate the position of a point on the display screen which corresponds to a point on some object, object space must be transformed into the eye coordinate system, which has its origin fixed at the viewpoint and its Ze axis pointed in the direction of view. World coordinate (right handed) to eye coordinate system ( change sign of z). choose so that X, Y axes allign GYTE-Makine Mühendisliği Bölümü

  3. 11. WireframePerspectiveDisplay A transformation called the viewing transformation V is used to convert points in object space (x, y, z) to points in the eye coordinate system (xe , ye , ze ). V-transformation matrix Concatenation of several rotations and translations. GYTE-Makine Mühendisliği Bölümü

  4. 11. WireframePerspectiveDisplay SimplePerspectiveTransformation Perspective display can be generated by projecting each point of an object onto the plane of the display screen. The coordinates (Xs , Ys ) of the projected image of the point P measured in eye coordinates (Xe , Ye , Ze) are easily computed. Considering the Ye , Zeplane: Triangles OQ'P' and OQP are similar, giving: Xs and Ys can be converted to dimensionless fractions by dividing the screen size: GYTE-Makine Mühendisliği Bölümü

  5. 11. WireframePerspectiveDisplay SimplePerspectiveTransformation or to screen coordinates by including a specification of the location of the image area (viewport): Here: GYTE-Makine Mühendisliği Bölümü

  6. 11. WireframePerspectiveDisplay SimplePerspectiveTransformation This transformation is fundamentally different from those for rotation, translation and scaling: it involves dividing by the Zecoordinate value, whereas the others involve only multiplication and addition. Generating a true perspective image requires dividing by the depth of each point. Pespective image of a line can be generated easily by transforming only its endpoints and drawing the line between the two transformed end points. The process of generating a wire-frame perspective display thus involves: a) Retrieving the object-space coordinates of the end points of each line and using viewing transformation equation to obtain the eye coordinates of the endpoints. b) AboveEqn. to find the screen coordinates of each endpoint. c) Vector generator can then generate a line from the endpoint information. If   is small aperture will be wide angle If is large, gives narrow aperture like a telephoto lens. GYTE-Makine Mühendisliği Bölümü

  7. 11. WireframePerspectiveDisplay 3D Clipping 3B Kırpma ekranda görüntülenebilecek (görünür) kısımların belirlenmesi ve görüntü dışı kalanların ayrılmasıdır. The conditions of visibility are: areexcluded. clippingcoordinatesor: (Xc, Yc, Zc): GYTE-Makine Mühendisliği Bölümü

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