# Computer Graphics Questions & Answers – Transformations between Coordinate Systems and Affine Transformations

This set of Computer Graphics Interview Questions and Answers focuses 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

Explanation: 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

Explanation: 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

Explanation: 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

Explanation: 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.
b) variable, affine
d) linear, affine

Explanation: 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

Explanation: Adding a vector to a point gives a point, but Subtracting points gives a vector.

7. Which of the following properties are preserved in affine transformation?
a) co-linearity
b) convexity
c) concavity
d) parallelism

Explanation: 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

Explanation: 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

Explanation: 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

Explanation: Due to the effect of similitude and similarity transform, the inverse is equal to the transpose. So, we can say that M-1 = Mt.

Sanfoundry Global Education & Learning Series – Computer Graphics.

To practice all areas of Computer Graphics for Interviews, here is complete set of 1000+ Multiple Choice Questions and Answers.

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