25. What do you mean by Perspective projection?
Perspective projection is one in which the lines of projection are not parallel. Instead, they all converge at a single point called the center of projection.
26. What is Projection reference point?
In Perspective projection, the lines of projection are not parallel. Instead, they all converge at a single point called Projection reference point.
27. What is the use of Projection reference point?
In Perspective projection, the object positions are transformed to the view plane along these converged projection line and the projected view of an object is determined by calculating the intersection of the converged projection lines with the view plane.
28. What are the different types of parallel projections?
The parallel projections are basically categorized into two types, depending on the relation between the direction of projection and the normal to the view plane. They are orthographic parallel projection and oblique projection.
29. What is orthographic parallel projection?
When the direction of the projection is normal (perpendicular) to the view plane then the projection is known as orthographic parallel projection
30. What is orthographic oblique projection?
When the direction of the projection is not normal (not perpendicular) to the view plane then the projection is known as oblique projection.
31. What is an axonometric orthographic projection?
The orthographic projection can display more than one face of an object. Such an orthographic projection is called axonometric orthographic projection.
32. What is cavalier projection?
The cavalier projection is one type of oblique projection, in which the direction of projection makes a 45-degree angle with the view plane.
33. What is cabinet projection?
The cabinet projection is one type of oblique projection, in which the direction of projection makes a n angle of arctan (2)=63.4- with the view plane.
34. What is vanishing point?
The perspective projections of any set of parallel lines that are not parallel to the projection plane converge to appoint known as vanishing point.
35. What do you mean by principle vanishing point.
The vanishing point of any set of lines that are parallel to one of the three principle axes of an object is referred to as a principle vanishing point or axis vanishing point.
36. What is view reference point?
The view reference point is the center of the viewing coordinate system. It is often chosen to be close to or on the surface of the some object in the scene.
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