Computer Graphics Questions and Answers Part-14

1. Scaling of a polygon is done by computing
a) The product of (x, y) of each vertex
b) (x, y) of end points
c) Center coordinates
d) Only a

Answer: d
Explanation: Scaling of a polygon is done by computing the product of (x, y) of each vertex with scaling factor sx and sy to produce the transformation coordinates ( Xnew, Ynew).

2. If the scaling factors values sx and sy < 1 then
a) It reduces the size of object
b) It increases the size of object
c) It stunts the shape of an object
d) None

Answer: a
Explanation: If the scaling factors values sx and sy < 1 then it reduces the size of object.

3. If the scaling factors values sx and sy are assigned to the same value then
a) Uniform rotation is produced
b) Uniform scaling is produced
c) Scaling cannot be done
d) Scaling can be done or cannot be done

Answer: b
Explanation: When sx and sy are assigned the same value then uniform scaling is produced that maintains relative object proportions.

4. If the scaling factors values sx and sy are assigned to unequal values then
a) Uniform rotation is produced
b) Uniform scaling is produced
c) Differential scaling is produced
d) Scaling cannot be done

Answer: c
Explanation: Unequal values for sx and sy results in differential scaling that is often used in design applications.

5. The objects transformed using the equation P’=S*P should be
a) Scaled
b) Repositioned
c) Both a and b
d) Neither a nor b

Answer: c
Explanation: The objects transformed using the equation P’=S*P should be scaled and repositioned.

6. We control the location of a scaled object by choosing the position is known as
a) Pivot point
b) Fixed point
c) Differential scaling
d) Uniform scaling

Answer: b
Explanation: Fixed point

7. If the value of sx=1 and sy=1 then
a) Reduce the size of object
b) Distort the picture
c) Produce an enlargement
d) No change in the size of an object

Answer: d
Explanation: sx=sx=1 does not change the size of the object.

8. The polygons are scaled by applying the following transformation.
a) X’=x * Sx + Xf(1-Sx) and Y’=y * Sy + Yf(1-Sy)
b) X’=x * Sx + Xf(1+Sx) and Y’=y * Sy + Yf(1+Sy)
c) X’=x * Sx + Xf(1-Sx) and Y’=y * Sy – Yf(1-Sy)
d) X’=x * Sx * Xf(1-Sx) and Y’=y * Sy * Yf(1-Sy)

Answer: a
Explanation: The polygons are scaled by applying the transformation X’=x * Sx + Xf(1-Sx) and Y’=y * Sy + Yf(1-Sy).

9. The matrix representation for translation in homogeneous coordinates is
a) P’=T+P
b) P’=S*P
c) P’=R*P
d) P’=T*P

Answer: d
Explanation: The matrix representation for translation is P’=T*P.

10. The matrix representation for scaling in homogeneous coordinates is
a) P’=S*P
b) P’=R*P
c) P’=dx+dy
d) P’=S*S

Answer: a
Explanation: The matrix representation for scaling is P’=S*P.