Q.1 Which of the following is the primary purpose of Hidden Surface Removal in computer graphics?
To improve color rendering
To eliminate non-visible surfaces
To increase shading accuracy
To reduce pixel resolution
Explanation - Hidden Surface Removal ensures that only visible surfaces of objects are displayed, improving realism and performance.
Correct answer is: To eliminate non-visible surfaces
Q.2 Which algorithm uses a depth buffer to resolve visibility problems?
Z-buffer algorithm
Scan-line algorithm
Painter’s algorithm
Ray casting
Explanation - The Z-buffer algorithm maintains depth information per pixel to determine visibility.
Correct answer is: Z-buffer algorithm
Q.3 In the Painter’s algorithm, surfaces are:
Drawn front to back
Drawn back to front
Hidden using depth buffers
Removed completely
Explanation - The Painter’s algorithm draws surfaces from farthest to nearest, overwriting nearer surfaces last.
Correct answer is: Drawn back to front
Q.4 Which hidden surface removal technique suffers from depth sorting issues with overlapping polygons?
Z-buffer
Painter’s algorithm
Ray tracing
Scan-line algorithm
Explanation - Painter’s algorithm faces problems when polygons overlap in complex ways, requiring splitting.
Correct answer is: Painter’s algorithm
Q.5 What is the main disadvantage of the Z-buffer algorithm?
High memory consumption
Inaccuracy in rendering
Slower than Painter’s algorithm
Requires polygon sorting
Explanation - Z-buffer requires additional memory proportional to screen resolution for storing depth values.
Correct answer is: High memory consumption
Q.6 Which algorithm is particularly efficient when dealing with convex polygons?
Z-buffer
Scan-line
Painter’s algorithm
Ray casting
Explanation - The Scan-line algorithm works efficiently with convex polygons by processing one line at a time.
Correct answer is: Scan-line
Q.7 Which of the following is NOT a hidden surface removal method?
Back-face culling
Z-buffer
Ray tracing
Dithering
Explanation - Dithering is a technique for color approximation, not surface visibility determination.
Correct answer is: Dithering
Q.8 Back-face culling removes surfaces that:
Are closest to the camera
Face away from the camera
Are transparent
Are partially visible
Explanation - Back-face culling eliminates polygons whose normals face away from the viewing direction.
Correct answer is: Face away from the camera
Q.9 Which mathematical property is commonly used in back-face culling?
Dot product
Cross product
Matrix multiplication
Vector addition
Explanation - The dot product between the surface normal and view vector determines visibility.
Correct answer is: Dot product
Q.10 Which algorithm is conceptually similar to painting with layers?
Z-buffer
Painter’s algorithm
Scan-line
Ray tracing
Explanation - The Painter’s algorithm simulates painting by drawing distant objects first and nearer ones on top.
Correct answer is: Painter’s algorithm
Q.11 In Z-buffering, what happens if two objects have the same depth value?
One is chosen randomly
The brighter one is shown
It depends on implementation
Both are discarded
Explanation - Tie-breaking strategies vary in Z-buffer implementations, often based on drawing order.
Correct answer is: It depends on implementation
Q.12 Hidden surface removal is essential in:
3D rendering
Image compression
Audio processing
2D sprite animation
Explanation - Only 3D rendering requires visibility checks to ensure realism.
Correct answer is: 3D rendering
Q.13 Which algorithm requires sorting of polygons based on depth?
Z-buffer
Painter’s algorithm
Scan-line
Back-face culling
Explanation - Painter’s algorithm sorts polygons by depth before rendering them.
Correct answer is: Painter’s algorithm
Q.14 The Z-buffer algorithm is also called:
Depth-buffer algorithm
Scan-line algorithm
Priority algorithm
Span-buffer algorithm
Explanation - Z-buffer is also known as the depth-buffer algorithm since it tracks pixel depth.
Correct answer is: Depth-buffer algorithm
Q.15 Which of the following is a disadvantage of Painter’s algorithm?
Requires a depth buffer
Fails with cyclic overlaps
Consumes large memory
Slows with resolution
Explanation - Painter’s algorithm fails when surfaces cyclically overlap since sorting becomes impossible.
Correct answer is: Fails with cyclic overlaps
Q.16 Back-face culling improves rendering performance by:
Reducing the polygon count
Adding realistic lighting
Using interpolation
Splitting polygons
Explanation - By skipping non-visible back-facing polygons, fewer polygons need to be processed.
Correct answer is: Reducing the polygon count
Q.17 Which of the following algorithms can handle transparency more naturally?
Z-buffer
Painter’s algorithm
Back-face culling
Scan-line
Explanation - Painter’s algorithm can better handle transparency since objects are drawn in back-to-front order.
Correct answer is: Painter’s algorithm
Q.18 The Z-buffer algorithm compares values for each:
Polygon
Edge
Pixel
Vertex
Explanation - Z-buffer operates at the pixel level, checking depth for each pixel rendered.
Correct answer is: Pixel
Q.19 Hidden surface removal is not required in:
Wireframe rendering
Solid rendering
Ray tracing
Rasterization
Explanation - In wireframe models, all edges are shown, so visibility checks are unnecessary.
Correct answer is: Wireframe rendering
Q.20 Which data structure is central to the Z-buffer algorithm?
Stack
Queue
Array
Linked list
Explanation - The Z-buffer is stored as a 2D array corresponding to screen pixels.
Correct answer is: Array
Q.21 Which of the following combines hidden surface removal with shading calculations?
Ray tracing
Back-face culling
Z-buffer
Scan-line
Explanation - Ray tracing inherently calculates visibility while computing lighting and shading.
Correct answer is: Ray tracing
Q.22 Which algorithm is best suited for hardware implementation in GPUs?
Painter’s algorithm
Z-buffer
Scan-line
Back-face culling
Explanation - Modern GPUs implement Z-buffering efficiently at the hardware level.
Correct answer is: Z-buffer
Q.23 Back-face culling cannot be applied when:
Surfaces are concave
Objects are convex
Normals are not computed
Camera is orthographic
Explanation - Back-face culling requires surface normals; without them, visibility cannot be checked.
Correct answer is: Normals are not computed
Q.24 Which algorithm requires polygon splitting to handle certain cases?
Z-buffer
Painter’s algorithm
Scan-line
Back-face culling
Explanation - When polygons overlap cyclically, Painter’s algorithm may require splitting polygons to resolve visibility.
Correct answer is: Painter’s algorithm
Q.25 Which method uses object space rather than image space for hidden surface removal?
Back-face culling
Z-buffer
Painter’s algorithm
Scan-line
Explanation - Back-face culling works in object space, checking orientation before projection to screen.
Correct answer is: Back-face culling