Computer Graphics Interview Questions and Answers on “Transformations between Coordinate Systems and Affine Transformations”.
1. A ___________ is a system which uses one or more numbers, or coordinates, to uniquely determine the position of a point.
a) co-ordinate system
b) binary-system
c) vector-system
d) euclid geometry
Answer: a
Clarification: A coordinate system is a system which uses one or more numbers, or coordinates, to uniquely determine the position of a point. It also determines the other geometric elements on a manifold on Euclid space.
2. Which of the co-ordinate represents X co-ordinate in (6,8,9)?
a) 6
b) 8
c) 9
d) 0
Answer: a
Clarification: In a co-ordinate system, any position of a point is denoted as (x,y,z). Where x denotes the perpendicular distance of the point from the x-axis. Hence x is the X co-ordinate.
3. Which of the co-ordinate represents Y co-ordinate in (6,8,9)?
a) 6
b) 8
c) 9
d) 0
Answer: b
Clarification: In a co-ordinate system, any position of a point is denoted as (x,y,z). Where y denotes the perpendicular distance of the point from the y-axis. Hence y is the Y co-ordinate.
4. Which of the co-ordinate represents Z co-ordinate in (6,8,9)?
a) 6
b) 8
c) 9
d) 0
Answer: c
Clarification: In a co-ordinate system, any position of a point is denoted as (x,y,z). Where z denotes the perpendicular distance of the point from the z-axis. Hence z is the Z co-ordinate.
5. _______________ and ___________ are two types of transformations.
a) quadratic, cubic
b) variable, affine
c) linear, quadratic
d) linear, affine
Answer: d
Clarification: Linear and affine transformations are two different types of transformations of matrices. In linear, points are in vector space but in affine, points are in affine space.
6. Adding points to a vector give a vector.
a) True
b) False
Answer: b
7. Which of the following properties are preserved in affine transformation?
a) co-linearity
b) convexity
c) concavity
d) parallelism
Answer: c
Clarification: The col-linearity, convexity and parallelism of bunch of points are conserved in affine transformations but any 3 or more points which are concave can turn parallel, so we can say concavity is not conserved.
8. Ratio of length along a line is preserved in affine transformations.
a) True
b) False
Answer: a
Clarification: The ratio of length gets preserved, for example, distinct collinear points x1,x2,x3. The ratio of x1x2 and x2x3 is same as that of f(x1)f(x2) and f(x2)f(x3).
9. Which co-ordinates allow common vector operations such as translation, rotation, scaling and perspective projection to be represented as a matrix by which the vector is multiplied.
a) vector co-ordinates
b) 3d co-ordinates
c) affine co-ordinates
d) homogenous co-ordinates
Answer: d
Clarification: The function of homogenous co-ordinates is to allow common vector operations such as translation, rotation, scaling and perspective projection to be represented as a matrix by which the vector is multiplied.
10. For orthonormal basis, which of these is correct?
a) M-1 = Mt
b) M-1 = Mt
c) M = M
d) Mt = I
Answer: a
Clarification: Due to the effect of similitude and similarity transform, the inverse is equal to the transpose. So, we can say that M-1 = Mt.