Computer Graphics (Lec3)

Lighting scene

a process of light simulation and how the light emits to the objects in the scene.

Lighting scene

It is crucial to provide a mood and making a visually appealing output.

No lighting

There are no lights in the scene and there is no interaction between the light and the object in the scene.

Ambient Light

It is a non-directional light sources and the light reflects many times from many surfaces which it appears equally from all directions.

Insert Camera models

are mathematical descriptions of how a 3D scene is projected onto a 2D image.

Insert Camera models

They allow us to control the viewpoint, perspective, and field of view, just like a real camera which are essential for rendering virtual environments.

Types of Camera Models

1. Orthographic Projection

2. Perspective Projection

Orthographic Projection

all the projection lines are parallel, and there's no perspective foreshortening.

Perspective Projection

The most common type of camera model and it's designed to mimic how our eyes see the world (Objects appear smaller as they get farther away, and parallel lines converge at a vanishing point).

Pinhole Camera Model

In the perspective projection, we have a ______, the simplest perspective camera model which uses similar geometry to project 3D points onto a 2D image plane.

Simple Reflection Models

1. Diffuse Reflection (Lambertian Reflection)

2. Specular Reflection

Diffuse Reflection (Lambertian Reflection)

When it uses a point light where it comes from a specific direction. It reflects equally in all direction. While, if it uses a directional light, is known faster than the point light, no computation needed for each polygon.

Specular Reflection

It is a reflection off of shiny surfaces such as shiny metal or plastic that is high in specular component. The position of the viewer is very important for the specular reflection.

Lighting and Shading

provides additional mood, realistic, and visually appearing scene we see in the screen.

There are two types of lighting:

hard lighting and soft lighting.

Hard Lighting

creates a sharp and well-defined shadows

soft lighting

produces more gradual transitions between the light and shadow.

Lighting types

are achieved depending to the light sources used to illuminate light behavior from the source to object.

Types of Light Sources

1. Directional Light

2. Point Light

3. Spotlight

Directional Light

A light that is produced by a light source where the light rays emanating from a single parallel direction.

Point Light

Provides an equal amount of light in all directions.

Example of this was the bulb light.

Spotlight

It radiates the light in a cone shape which is like a flash light.

Shading or Shading Models?

This determines the color of a 3D objects surface by calculating the lighting, material properties, etc. which creates a realistic scene. Crucial to provide a realistic and appealing visualization.

Types of Shading Models

1. Flat Shading (Constant Shading)

2. Gouraud Shading (Interpolated Shading)

3. Phong Shading (Normal Interpolation Shading)

Flat Shading (Constant Shading)

It calculates the color once of each face of 3D polygon.

Very fast but unrealistic.

Gouraud Shading (Interpolated Shading)

It calculates the color in each vertex then interpolate these colors across the face.

Provide smoother appearance of shading.

Phong Shading (Normal Interpolation Shading)

It interpolates the surface normal across the polygon and calculate the lighting equation at each pixel.

It creates more accurate and realistic shading.