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Definition
- An Illumination Model is a mathematical model used in computer and multimedia graphics to calculate how light interacts with objects and surfaces to produce realistic images.
- It is a mathematical method used in multimedia graphics to calculate light reflection on objects to create realistic images.
Characteristics
- It includes ambient, diffuse, and specular reflection components.
- Examples include local and global illumination models such as the Phong model.
- An illumination model helps in determining brightness, color, shading, reflection, etc.
Why Illumination Model is Important?
- Without illumination, objects look flat, no depth perception, no realistic appearance, etc.
- Illumination models help create realistic 2D and 3D scenes in multimedia applications.
- The concept is used in software like Blender and Autodesk Maya.
Types of Illumination Models
Local Illumination Model
- This model considers light directly from a light source.
- This model does not consider reflection from other objects.
- This model is faster and simpler.
- For example, Phong Illumination Model.
Global Illumination Model
- This model considers reflection, refraction, and indirect light.
- This model produces realistic shadows and lighting.
- This model is more complex and slower.
- This model is used in advanced rendering engines.
Components of the Illumination Model
Most of the illumination models include three main components-
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Ambient Reflection
- It has a general background light.
- It prevents completely dark areas.
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Diffuse Reflection
- In this, light is scattered equally.
- It depends on the surface angle.
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Specular Reflection
- It produces shiny highlights.
- It depends on the viewer’s position.
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Phong Illumination Model
- It is developed by ‘Bui Tuong Phong’.
- It is the combination of ambient, diffuse, and specular components.
- It is widely used in multimedia graphics for smooth shading.
Use/Applications of the Illumination Model
- In 3D animation work.
- In Game development.
- In Virtual reality.
- In CAD design.
Shading
- Shading is the process of adding light and color effects to surfaces in computer graphics to make objects look realistic and three-dimensional.
- It determines how light interacts with the surface of an object.
- Shading is important because, i.e., without shading, objects look flat, no depth perception. no realistic appearance, etc.
- Shading creates smooth surfaces, realistic lighting, shadow effects, depth illusion, etc.
- The shadow concept is used in software like Blender and Autodesk Maya.
Types of Shading
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Flat Shading
- This shading has one color per polygon.
- In this, lighting is calculated once per surface.
- It is fast but not smooth.
- It is used in simple graphics.
- It produces sharp edges.
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Gouraud Shading
- In this, the lighting is calculated at the vertices.
- In this, colors are interpolated across the surface.
- It is smoother than flat shading.
- It is faster than Phong.
- It reduces sharp edges.
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Phong Shading
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- In this, lighting is calculated at every pixel.
- It produces smooth and shiny surfaces.
- It is more realistic.
- It is developed based on the work of Bui Tuong Phong.
- It has the best visual quality.
- It is slower than Gouraud.
Ray Tracing
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