1. If the original point P = (5, 7, 3) and the translation factor, T = (-2, -1, 3), then what will be the value of the final point P1?
a) P1 = (7, 8, 6)
b) P1 = (3, 6, 0)
c) P1 = (7, 8, 0)
d) P1 = (3, 6, 6)
Explanation: The new coordinates can be obtained by adding dx to x, dy to y and dz to z as:
x1 = dx + x ; y1 = dy + y ; z1 = dz + z
So, P1 = (5+(-2), 7+(-1), 3+3)
P1 = (3, 6, 6)
2. How many different types of translation are present in computer graphics?
a) 1
b) 2
c) 3
d) 4
Explanation: In computer graphics, there are 3 types of translation techniques namely – the point translation (deals with a single point), the line translation (deals with a line) and the polygon translation (deals with a shape).
3. Which of the following operation can be applied on a 3 D object to zoom it in or out about any axis from its original position?
a) Translation
b) Scaling
c) Rotation
d) Shearing
Explanation: In computer graphics, scaling is a process of modifying or altering the size of objects. Scaling may be used to increase or reduce the size of object.
4. Which of the following operation can be applied on a 3 D object to rotate it about any axis from its original position?
a) Translation
b) Scaling
c) Rotation
d) Shearing
Explanation: The process of rotation is applied on a 3 D object to rotate it about any axis from its original position. The rotation of the object can be in clockwise direction or in anti-clockwise direction. We must specify the angle of rotation and the rotational point while performing the rotation transformation.
5. The positive value of the pivot point rotates an object in which of the following position?
a) Clockwise
b) Anti-Clockwise
c) Both Clockwise and Anti-Clockwise
d) Neither Clockwise nor Anti-Clockwise
Explanation: An object can be rotated in two ways – either clockwise or anticlockwise. If the rotation value of pivot point of the object is positive then the object is rotated in anti-clockwise direction and if the rotation value of pivot point of the object is negative then the object is rotated in clockwise direction.
6. Every vertex in a polygon is rotated with the same rotation angle.
a) True
b) False
Explanation: When we apply 3 D rotation on any three dimensional polygon then the polygon is rotated by shifting every vertex using the same rotational angle. When the object is rotated, then every point of the object is rotated by the same angle.
7. Which of the following equation is correct for the new Y co-ordinate if an object undergoes 3D rotation around x axis?
a) Ynew = Yold x cosθ – Zold x sinθ
b) Ynew = Yold x sinθ – Zold x cosθ
c) Ynew = Yold x cosθ + Zold x sinθ
d) Ynew = Yold x sinθ + Zold x cosθ
Explanation: The correct equation for the new Y co-ordinate if an object undergoes 3D rotation around x axis is – Ynew = Yold x cosθ – Zold x sinθ.
When the matrix form for 3D rotation around x axis is expanded then we get the following equations – Xnew = Xold; Ynew = Yold x cosθ – Zold x sinθ; Znew = Yold x sinθ + Zold x cosθ.
8. Which of the following equation is correct for the new Z co-ordinate if an object undergoes 3D rotation around y axis?
a) Znew = Yold x cosθ + Xold x sinθ
b) Znew = Yold x cosθ – Xold x sinθ
c) Znew = Yold x sinθ + Xold x cosθ
d) Znew = Yold x sinθ – Xold x cosθ
Explanation: The correct equation for the new Y co-ordinate if an object undergoes 3D rotation around x axis is – Znew = Yold x cosθ – Xold x sinθ.
When the matrix form for 3D rotation around x axis is expanded then we get the following equations – Xnew = Zold x sinθ + Xold x cosθ; Ynew = Yold; Znew = Yold x cosθ – Xold x sinθ
9. What does composite transformations means?
a) Transformations that can be done in sequence
b) Transformations that cannot be done in sequence
c) Transformations that can be done simultaneously
d) Transformations that cannot be done simultaneously
Explanation: Composite transformations are transforms that may be done in sequence, hence they can be concatenated. Here we compose two or more than two transformations together and calculate a resultant transformation matrix by multiplying all the corresponding transformation matrix conditions with each other.
10. A normal scaling operation also moves the object being scaled from its original points.
a) True
b) False
Explanation: It is true that the normal scaling operation also moves the object being scaled from its original points. As an object scale from its original points its size increases due to which its end points changes and it moves from its original position.