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reflected light ~ cosθ

reflected light ~ tanθ

reflected light ~ sinθ

Which is NOT true about texture mapping?

It is a technique of mapping a 2D image (texture) onto a 3D object (shape).

It is a cheap way to produce realistic scenes (images).

It takes a lot of computing resources such as GPU and memory compared to other techniques.

After (pure) texture mapping, the resulting surface will be smooth.

Which shading is described by the following?

This is one of the smooth shading methods. The lighting (light intensity) is calculated at each vertex and interpolated across the surface for interior pixels. If polygon mesh surfaces have high curvatures, this shading may show edges.

Toon (cel) shading

Gouraud shading

Phong shading

Flat shading

vec3 light = uLightPosition.xyz;

The following shows an excerpt of the code for a vertex lighting shader. What does the code with red colour calculate?

vec3 pos = -(uModelViewMatrix * aPosition).xyz;

vec3 L = normalize( light - pos );

vec3 E = normalize( -pos );

vec3 H = normalize( L + E );

Normal vector

Light vector

Halfway vector

View vector

What is the benefit of using Blinn-Phong reflection model instead of Phong reflection model?

There is no huge benefit.

We use the halfway vector (instead of the r vector) which never exceeds 90 degrees (thus, more realistic images are generated).

An image created by Blinn-Phong reflection model looks more artistic.

The halfway angle is twice of the angle between r and v. Thus, the image by Blinn-Phong reflection model is more expressive.

What is described by the following?

This is an interpolation technique. For each point of the surface, the surface normals are interpolated to calculate the light intensity.

Ray tracing

Phong shading

Goraud shading

Phong reflection model

What is represented by the following equation?

Phong reflection model without the distance term

Gouraud shading

Phong shading

Phong reflection model with the distance term

In (real-time) Computer Graphics, what is important? (Choose the best answer based on what you have learned in class.)

Rendering things that are physically accurate

Rendering things fast and efficiently

Rendering things that will make viewers happy

Rendering things that look right

Projecting a polygon from a point light source onto a surface is one of the oldest methods of creating a shadow. If we project a shadow onto the ground at y = 0, which perspective projection matrix is used?

( A )

( C )

( D )

( B )

What type of surface is described by the following?

This has a smooth surface that shows highlights (as seen in the figure below) resulting from incoming light being reflected in directions concentrated close to the direction of a perfect reflection.

Transparent surface

Specular surface

Diffuse surface

Translucent surface