Q.1 Which of the following is a local illumination model in computer graphics?
Phong reflection model
Ray tracing
Radiosity
Global illumination
Explanation - Local illumination models compute lighting at a surface point considering only light sources and surface properties at that point, without considering interreflections.
Correct answer is: Phong reflection model
Q.2 In Phong shading, which component is responsible for the shiny highlights observed on glossy surfaces?
Ambient
Diffuse
Specular
Reflection
Explanation - The specular component simulates mirror-like reflection, producing bright highlights on surfaces.
Correct answer is: Specular
Q.3 Which shading model calculates illumination per vertex and interpolates the results across the surface?
Flat shading
Gouraud shading
Phong shading
Radiosity
Explanation - Gouraud shading computes lighting at the vertices and interpolates color values over the polygon surface.
Correct answer is: Gouraud shading
Q.4 Which shading technique computes color per pixel for smoother highlights?
Flat shading
Gouraud shading
Phong shading
Z-buffer shading
Explanation - Phong shading interpolates surface normals across the polygon and computes lighting per pixel for realistic highlights.
Correct answer is: Phong shading
Q.5 In computer graphics, ambient light is used to:
Simulate shadows
Represent indirect light scattered in the environment
Create specular highlights
Determine surface texture
Explanation - Ambient light is a constant illumination term that approximates indirect, non-directional light.
Correct answer is: Represent indirect light scattered in the environment
Q.6 Which lighting model accounts for energy transfer between surfaces?
Phong model
Gouraud shading
Radiosity
Flat shading
Explanation - Radiosity is a global illumination technique that calculates diffuse interreflections of light between surfaces.
Correct answer is: Radiosity
Q.7 The diffuse reflection component depends primarily on:
Viewer's position
Light source position and surface normal
Material specularity
Texture mapping
Explanation - Diffuse reflection is based on Lambert’s cosine law, depending on the angle between the surface normal and light direction.
Correct answer is: Light source position and surface normal
Q.8 Which of the following is NOT a common shading model?
Flat shading
Gouraud shading
Phong shading
Bezier shading
Explanation - Bezier refers to curve representation, not a shading model.
Correct answer is: Bezier shading
Q.9 Specular reflection intensity decreases when:
Viewer moves closer to surface
Angle between reflection and viewer increases
Surface becomes more polished
Light intensity increases
Explanation - Specular highlights are strongest when the reflection direction aligns with the viewer direction and weaken as the angle diverges.
Correct answer is: Angle between reflection and viewer increases
Q.10 Which lighting technique is more computationally expensive but produces realistic soft shadows?
Local illumination
Flat shading
Global illumination
Gouraud shading
Explanation - Global illumination considers both direct and indirect lighting, including interreflections, making it computationally intensive but realistic.
Correct answer is: Global illumination
Q.11 Flat shading computes color for:
Each vertex
Each pixel
Each polygon
Each fragment shader
Explanation - Flat shading applies a single color to the entire polygon based on one normal, leading to a faceted look.
Correct answer is: Each polygon
Q.12 Phong reflection model combines which three components?
Ambient, Diffuse, Specular
Direct, Indirect, Ambient
Diffuse, Specular, Transmission
Ambient, Reflection, Refraction
Explanation - Phong model sums ambient, diffuse, and specular contributions to compute final pixel color.
Correct answer is: Ambient, Diffuse, Specular
Q.13 Which model is particularly used for simulating interreflections on diffuse surfaces?
Phong model
Radiosity
Gouraud shading
Flat shading
Explanation - Radiosity is suited for diffuse surfaces and computes energy exchange between surfaces.
Correct answer is: Radiosity
Q.14 In Gouraud shading, a disadvantage is:
Expensive per-pixel computation
Specular highlights can be lost
Requires global illumination
Cannot render polygons
Explanation - Since Gouraud shading interpolates vertex colors, small specular highlights may not appear if they don’t coincide with a vertex.
Correct answer is: Specular highlights can be lost
Q.15 Which of the following is a global illumination effect?
Specular highlight
Diffuse reflection
Color bleeding
Flat shading
Explanation - Color bleeding occurs when light reflected from one surface affects the color of nearby surfaces, a global illumination effect.
Correct answer is: Color bleeding
Q.16 Which shading method produces a smooth appearance without computing per-pixel lighting?
Flat shading
Gouraud shading
Phong shading
Radiosity
Explanation - Gouraud shading interpolates vertex lighting across the polygon, giving a smooth look without per-pixel computation.
Correct answer is: Gouraud shading
Q.17 The ambient reflection term is independent of:
Surface color
Light intensity
Surface normal
Material properties
Explanation - Ambient reflection is uniform across surfaces and does not depend on surface orientation.
Correct answer is: Surface normal
Q.18 Phong shading interpolates which quantity across the polygon?
Vertex colors
Surface normals
Texture coordinates
Lighting intensity
Explanation - Phong shading interpolates normals and calculates lighting per pixel for smooth highlights.
Correct answer is: Surface normals
Q.19 Which shading model is most suitable for hardware-accelerated graphics pipelines?
Radiosity
Gouraud shading
Ray tracing
Global illumination
Explanation - Gouraud shading is efficient for real-time rendering and widely used in graphics hardware.
Correct answer is: Gouraud shading
Q.20 Which component in lighting models simulates indirect light in a simplified manner?
Ambient
Diffuse
Specular
Refraction
Explanation - Ambient light is a simplified way to simulate scattered indirect light without actual calculations.
Correct answer is: Ambient
Q.21 Which shading technique would produce faceted-looking surfaces?
Phong shading
Gouraud shading
Flat shading
Radiosity
Explanation - Flat shading assigns a single color to each polygon, resulting in a faceted appearance.
Correct answer is: Flat shading
Q.22 Which model uses the cosine of the angle between light direction and surface normal?
Specular reflection
Diffuse reflection
Ambient reflection
Reflection mapping
Explanation - Lambert’s cosine law states that diffuse reflection intensity is proportional to the cosine of the angle between the light and surface normal.
Correct answer is: Diffuse reflection
Q.23 Which global illumination algorithm is based on energy balance between surfaces?
Gouraud shading
Phong shading
Radiosity
Flat shading
Explanation - Radiosity computes energy exchange between diffuse surfaces ensuring energy conservation.
Correct answer is: Radiosity
Q.24 Which shading model is best for simulating realistic highlights on shiny surfaces?
Flat shading
Gouraud shading
Phong shading
Radiosity
Explanation - Phong shading calculates per-pixel lighting using interpolated normals, producing accurate specular highlights.
Correct answer is: Phong shading
Q.25 Which type of illumination model considers only the local surface properties and light sources?
Local illumination
Global illumination
Radiosity
Ray tracing
Explanation - Local illumination models ignore light interactions between surfaces and compute lighting based on direct sources only.
Correct answer is: Local illumination