CG quizz

Aliasing is the result of:

• a) Transformation

• b) Rasterization

• c) Depth-handling

• d) Shading

• e) Projection

2. How can a matrix composition be inverted?

• a) by multiplying the individual matrices in reverse order

• b) by multiplying the inverse of the individual matrices in same order

• c) by multiplying the individual matrices in same order

• d) by multiplying the inverse of the individual matrices in reverse order

Answer explanation

Comment: To invert a matrix composition, you need to calculate the inverse of each individual matrix and then multiply them in reverse order.

Which of the following statements is correct for the barycentric coordinates (a,b,c) of a triangle?

• a) a + c = 1 - b

• b) they are not independent (right as well)

• c) if a,b,c are each >= 0 and <= 1 then the corresponding point is always inside the triangle

Answer explanation

Comment: Barycentric coordinates are used to represent a point within a triangle using the triangle's vertices' weights. If a, b, and c are between 0 and 1, the point lies inside the triangle.

Irradiance(environment) maps are used for simulating bumpy material?

• a) true

• b) false

Answer explanation

Comment: Irradiance maps are used to simulate global illumination and indirect lighting, not for simulating bumpy materials. Bump maps or normal maps are used for simulating bumpy materials.

Let d2 be the value in the shadow map at a scene point and d1 be the distance of the scene point to the light source. The scene point is in shadow if:

• a) d1 > d2

• b) d1 = d2

• c) d2 > d1

The bidirectional reflectance distribution function (BRDF) does follow the Helmholtz reciprocity (duality of light-transport)

• true

• false

Answer explanation

Comment: The BRDF follows the Helmholtz reciprocity principle, which states that the exchange of incoming and outgoing directions does not change the value of the BRDF.

In 3d homogeneous coordinate is always the z coordinate of a vertex and is required for perspective projection?

• true

• false

Answer explanation

Comment: In 3D homogeneous coordinates, the fourth coordinate (usually represented as 'w') is used for perspective projection, not the z coordinate.

Normal vectors are used in computer graphics for?

• Supporting shading computations

• Ensuring correct results of projections

• Indicating back- and front-faces of triangles

• Enabling the depth buffer algorithm

Answer explanation

Comment: Normal vectors are used to represent the surface orientation, which is crucial for shading computations, such as calculating lighting and reflections.

What are simple possibilities to increase render performance?

• a) using triangle strips and fans

• b) computing the homogeneous division after perspective projection

• c) enabling backface culling

Answer explanation

Comment: Both triangle strips and fans reduce the number of vertices needed for rendering, while backface culling discards triangles that are not visible, reducing the rendering load.

Which components in what order does a classical graphics pipeline consist of?

• a. backface culling --> dipping --> transformation --> homogeneous division --> rasterization

• b. transformation --> clipping --> homogeneous division --> backface culling --> rasterization

• c. clipping» transformation --> backface culling --> homogeneous division --> rasterization

• d. transformation --> backface culling --> clipping --> homogeneous division --> rasterization

Answer explanation

Comment: The classical graphics pipeline processes vertices in the following order: transformation, backface culling, clipping, homogeneous division, and rasterization.