1. In terms of a line, which of the following means fixed point scaling?
a) Both endpoints of the line remains same even after scale
b) Both endpoints of the line changes after scaling
c) One endpoint of the line remains same after scaling
d) The line can be scaled only till a fixed point
Explanation: Fixed point scaling refers to one endpoint of the line remains same even after scaling. If we scale a line from both its endpoints then it changes its position so, to keep an endpoint same we only scale the line with respect to only one of the endpoint.
2. Which of the following is the first step in composite transformation performed to scale a line with a fixed end point?
a) Changing the position of the line so that the origin and the line’s endpoint overlaps
b) Keeping the origin same and scaling the line with respect to the origin
c) Changing the position of the line so that the endpoint and the fixed endpoint of the line overlaps
d) Keeping the end point same and scaling the line with respect to the endpoint
Explanation: The first step in composite transformation performed to scale a line with a fixed endpoint is to translating the line so that its end coincides with the origin. After this step only that endpoint is scaled which is not on the origin and then the non-scaled endpoint is translated back to its original position.
3. Composite transformations increases the number of operations performed in a series of transformation.
a) True
b) False
Explanation: Composite transformation decreases the number of operations performed in a series of transformation. The resultant matrix is obtained by only multiplying the given two matrices whereas in simple transformations every single point of an object has to be multiplied with the given matrix which increases the operations.
4. What should be sequence of transformations that are required to perform rotation of an object around an arbitrary point?
a) Inverse Translation, Rotation, Translation
b) Scaling, Translation, Rotation
c) Translation, Rotation, Inverse Translation
d) Rotation, Translation, Scaling
Explanation: The sequence of transformations that are required to perform rotation of an object around an arbitrary point is – Translation, Rotation, Inverse Translation.
First the object is translated to origin, then it is rotated and then inverse translated back to its original point.
5. Which of the following process is analogous to creating a view of a three dimensional scene?
a) Making a painting
b) Taking a photograph
c) Recording a sound
d) Editing a picture
Explanation: Taking a photograph is the most analogous to creating a view of a three dimensional scene because both of them involves similar steps to complete the process like viewing orientation, camera position and size of clipping window.
6. How many steps are involved in converting the world coordinates of a scene to device coordinates?
a) 2
b) 3
c) 5
d) 7
Explanation: A total of 5 steps are involved in converting the world coordinates of a scene to the device coordinates. These includes – Modelling Transformation, Viewing Transformation, Projection Transformation, Normalization Transformation and clipping and Viewport Transformation.
7. Which of the following step involves in placing the object into appropriate position within the scene using their world coordinates?
a) Modelling Transformation
b) Viewing Transformation
c) Projection Transformation
d) Viewport Transformation
Explanation: Modelling Transformation involves in placing the object into appropriate position within the scene using their world coordinates. In this step the shape of individual objects in a scene is constructed within the modelling coordinate and are placed into appropriate positions within the world coordinates.
8. Which of the following step involves converting viewing coordinates of a scene to the coordinate position on the projection plane?
a) Modelling Transformation
b) Viewing Transformation
c) Projection Transformation
d) Viewport Transformation
Explanation: Projection Transformation involves converting viewing coordinates of a scene to the coordinate position on the projection plane. This process involves mapping of the object point onto its image at the projection plane.
9. The Viewing plane or the projector is set up in which of the following position?
a) Perpendicular to x and aligned with y, z
b) Perpendicular to y and aligned with x, z
c) At origin
d) Perpendicular to z and aligned with x, y
Explanation: The viewing plane or the projector is set up in the direction perpendicular to z and aligned with x, y. These viewing coordinates describes a 3D object with respect to a viewer. The viewing plane also includes the view reference point which is the origin of the viewing plane.
10. Look vector points towards the direction in which the camera is looking.
a) True
b) False
Explanation: Look vector points towards the direction in which the camera is looking. It has three degrees of freedom and can be any vector in 3-space. Up vector is used to determine how the camera will be rotated around the look vector.