1. Explain the three dimensional display methods?
• Parallel projection
• The production of the 2D display of the 3D scene is called projection
• Project points on the object surface along the parallel lines on to the display plane
• Different 2D views of objects can be produced by projecting the visible points
• Perspective projection
• Done by the projecting points to the display plane along the converging points
• Causes the objects farther from the viewing point should be smaller of the same sized object present here.
• Depth CUEING
• Basic problem for visualization techniques is called depth cueing
• Some 3D objects are without depth information
• Visible line and surface identification
• To highlight the visible lines
• Display visible lines as dashed lines
• Removing the invisible lines
• Surface rendering
• Lightening conditions in the screen
• Assigned characteristics
• Degree of transparency
• How rough or smooth the surfaces are to be
• Exploded and cutaway views
• Three dimensional and stereoscopic views
2. Explain spline representation
• It is referred to a curve drawn in a different manner
• Interpolation and approximation splines
• Set of coordinate points called control points
• Curve can be translated , rotated and scaled
• Enclosing a set of points called convex hull
• Set of connected points is often called control graph
• Parametric continuity condition
• Geometric continuity condition
• Spline specification
3. Explain Bezier curves and surfaces
• Have number of properties
• Can be fitted to any number of control points
• Polynomial functions between p0 and pn n P(u) = pk BEZ k,n(u) K = 0
• Calculated x(u), y(u), z(u)
• Properties of Bezier curves
• Cubic Bezier curves
• Design techniques in Bezier curves
• Bezier surfaces
4. Explain general three dimensional rotations
• Transformation sequences
• P’ = T’.Rx ( ) .T.P
• Rotation in five steps
• Translate the object that rotates in parallel coordinate axis
• Rotate the object with one coordinate axis
• Apply inverse rotation to its original position
• Apply inverse translation to its original position
• V = p2 – p1
• After rotation to original position R( ) = T’.M.T
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