Q.1 What is the primary purpose of the viewing transformation in computer graphics?
To convert 3D world coordinates into 2D screen coordinates
To create 3D models from 2D images
To apply shading and lighting effects
To improve the rendering speed of polygons
Explanation - Viewing transformation converts world coordinates of objects into a view that can be mapped onto a 2D screen.
Correct answer is: To convert 3D world coordinates into 2D screen coordinates
Q.2 Which coordinate system is directly used by the display device in computer graphics?
World coordinates
Normalized device coordinates
Device coordinates
View coordinates
Explanation - Device coordinates correspond to the actual pixel locations on the display device.
Correct answer is: Device coordinates
Q.3 In 3D graphics, the viewing pipeline generally includes all the following except:
Modeling transformation
Viewing transformation
Clipping
Hidden surface removal
Explanation - The viewing pipeline mainly focuses on transforming from world coordinates to screen coordinates, clipping, and hidden surface removal. Modeling transformations are part of model creation, not viewing.
Correct answer is: Modeling transformation
Q.4 Which of the following is used to remove objects or portions of objects that lie outside the viewing volume?
Projection
Clipping
Transformation
Rasterization
Explanation - Clipping removes objects or parts of objects outside the view to optimize rendering and display only the visible portion.
Correct answer is: Clipping
Q.5 The Cohen-Sutherland algorithm is used for:
3D polygon rendering
Line clipping in 2D
Hidden surface removal
Shading of polygons
Explanation - Cohen-Sutherland algorithm efficiently clips lines against a rectangular clipping window in 2D space.
Correct answer is: Line clipping in 2D
Q.6 In the Cohen-Sutherland line clipping algorithm, what does the region code '0001' represent?
Line is completely inside the window
Line is above the window
Line is to the right of the window
Line is below the window
Explanation - Region codes indicate position relative to the clipping window. '0001' typically denotes the bottom region.
Correct answer is: Line is below the window
Q.7 The Liang-Barsky algorithm is preferred over Cohen-Sutherland because:
It handles curves better
It uses fewer intersection calculations
It can clip 3D surfaces
It supports non-rectangular windows
Explanation - Liang-Barsky algorithm is more efficient for line clipping as it reduces the number of computations compared to Cohen-Sutherland.
Correct answer is: It uses fewer intersection calculations
Q.8 Which projection type preserves parallelism of lines?
Perspective projection
Orthographic projection
Curvilinear projection
Oblique projection
Explanation - Orthographic projection preserves parallel lines and does not introduce perspective distortion.
Correct answer is: Orthographic projection
Q.9 In 3D viewing, the view plane is:
Parallel to the image plane
Perpendicular to the viewing direction
The same as the world coordinate plane
An arbitrary plane with no relation to the camera
Explanation - The view plane is perpendicular to the line of sight, where the projection of objects is formed.
Correct answer is: Perpendicular to the viewing direction
Q.10 Which of the following is NOT a step in the 3D viewing pipeline?
World to view transformation
View to projection transformation
Projection to screen transformation
Lighting transformation
Explanation - Lighting transformation is part of shading/rendering, not the 3D viewing pipeline.
Correct answer is: Lighting transformation
Q.11 In 2D clipping, the Sutherland-Hodgman algorithm is used for:
Polygon clipping
Line clipping
Point clipping
Curve clipping
Explanation - Sutherland-Hodgman algorithm clips polygons against a rectangular clipping window efficiently.
Correct answer is: Polygon clipping
Q.12 Normalized device coordinates (NDC) range from:
0 to 1
-1 to 1
0 to 100
-100 to 100
Explanation - After perspective division, coordinates are mapped to NDC in the range [-1, 1] along each axis.
Correct answer is: -1 to 1
Q.13 Which of the following is true about perspective projection?
Parallel lines remain parallel
Objects appear smaller as they are farther from the viewer
Angles are preserved
Depth information is lost
Explanation - Perspective projection simulates human vision, making distant objects appear smaller, unlike orthographic projection.
Correct answer is: Objects appear smaller as they are farther from the viewer
Q.14 The viewing reference point (VRP) is:
A point on the view plane representing the center of projection
The origin of world coordinates
A corner of the clipping window
The vanishing point in perspective projection
Explanation - VRP is the point from which the viewer is looking at the scene, usually at the center of the view plane.
Correct answer is: A point on the view plane representing the center of projection
Q.15 Clipping in 3D involves removing objects outside the:
World coordinates
Viewport
Viewing volume
Screen coordinates
Explanation - 3D clipping discards objects outside the viewing volume (frustum or cuboid) to improve rendering efficiency.
Correct answer is: Viewing volume
Q.16 The z-buffer algorithm is mainly used for:
Clipping lines
Hidden surface removal
Texture mapping
Antialiasing
Explanation - Z-buffer keeps track of depth values for pixels to remove hidden surfaces during rendering.
Correct answer is: Hidden surface removal
Q.17 Which of the following is NOT a type of 3D projection?
Orthographic
Oblique
Perspective
Raster
Explanation - Raster refers to the pixel grid for display, not a projection method.
Correct answer is: Raster
Q.18 Viewport transformation maps the normalized device coordinates to:
World coordinates
Device coordinates
Clip coordinates
Eye coordinates
Explanation - Viewport transformation converts normalized coordinates into actual pixel positions on the output device.
Correct answer is: Device coordinates
Q.19 In 2D clipping, trivial accept/reject tests are based on:
Intersection with clipping edges
Region codes of endpoints
Polygon area
Line slope
Explanation - Cohen-Sutherland uses region codes to quickly accept or reject lines before performing intersection calculations.
Correct answer is: Region codes of endpoints
Q.20 The canonical view volume in 3D graphics is defined as a cuboid in:
World coordinates
Normalized device coordinates
View coordinates
Screen coordinates
Explanation - After projection, the view volume is mapped to a canonical cuboid in NDC space to simplify clipping and viewport mapping.
Correct answer is: Normalized device coordinates
Q.21 Oblique projection is characterized by:
Depth foreshortening along all axes
Projection lines perpendicular to the projection plane
Projection lines at an angle to the projection plane
Perspective foreshortening
Explanation - Oblique projection projects points along parallel lines that are at an angle to the projection plane, not perpendicular.
Correct answer is: Projection lines at an angle to the projection plane
Q.22 Which of the following is a major advantage of clipping in computer graphics?
Improves realism of shading
Reduces computation by discarding unseen objects
Increases polygon detail
Allows anti-aliasing
Explanation - Clipping ensures only visible portions of objects are processed and rendered, improving efficiency.
Correct answer is: Reduces computation by discarding unseen objects
Q.23 In 3D graphics, the front and back planes define:
The limits of the view volume along the viewing direction
The size of the screen
The coordinate axes
The lighting direction
Explanation - The front (near) and back (far) planes bound the view volume, limiting which objects are visible.
Correct answer is: The limits of the view volume along the viewing direction
Q.24 In perspective projection, the vanishing point is:
Where parallel lines converge
The center of the world coordinates
The origin of the camera
The intersection of viewport and device coordinates
Explanation - Perspective projection simulates real-world perception, where parallel lines appear to meet at a vanishing point on the horizon.
Correct answer is: Where parallel lines converge