Oh man I feel like I have blogged in a while (which is probably extremely accurate since life has been so crazy busy). Well now I'm back and going to focus on different types of Mapping in this blog. I may also create another corresponding blog that will show you how to create certain maps and may even show you have to write the shader for one of the types of mapping.
Now Mapping is a type of computer graphics technique that allows you to create different effects by changing the aspects of a 3D model. There are a few different types of Mapping such as Displacement Mapping, Bump Mapping, Normal Mapping and Parallax Mapping.
DISPLACEMENT MAPPING
Displacement Mapping is a computer graphics technique that uses a texture, often referred to as a height map, that creates an effect where the position of the vertices of a model are displaced in order to create a change in the model's geometry and add geometric detail to the model surface. Essentially displacement mapping uses input from the info stored in a texture map to create bumps, creases, ridges, etc in the model's actual mesh. By actually deforming the mesh shadows can be created by the deformations, and can also occlude the other objects.
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BUMP MAPPING
Bump mapping like displacement mapping is a technique in computer graphics that uses a type of texture that stores input usesd to create the illusion of bumps and wrinkles on the surface area of an object. Unlike Displacement Mapping, Bump Mapping doesn't physically alter the model but instead simply creates the illusion of surface alteration. Due to the fact that Bump Mapping doesn't actually alter the surface geometry the 'bumps' and 'creases' cannot create shadows or obscure other objects.
Essentially Bump mapping utilizes the data stored in the texture, known as a bump map (or height Map), and perturbs the surface normals of the objects and using the perturbed normals during lighting calculations. This creates the appearance of a bumping surface even though the actual surface remains unchanged. The advantage of using bump mapping over Displacement Mapping is that its much faster and requires less resources for the same level of detail.
Bump Map Example:
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NORMAL MAPPING
Like Bump Mapping, Normal Mapping is a technique in computer graphics that is used to fake the lighting of bumps and dents, and is essentially an implementation of Bump Mapping. Normal Mapping is used to add details without adding more details and is a commonly used to enhance the appearance and details of low polygon models. To achieve this you generate a normal map from a high polygon model or height map.
Normal maps are commonly stored as regular RGB images where the RGB components corresponds to the X, Y and Z coordinates of the surface normal.
Normal Map Example:
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PARALLAX MAPPING
Parallax mapping, often referred to as offset mapping, is an enhancement of bump and normal mapping techniques applied to textures in 3D rendering applications. Parallax Mapping is implemented by displacing the texture coordinates at a point on the rendered polygon by a function of the view angle in the tangent space and the value of the height map at the point. This technique displaces the individual pixel height of a surface, so that when you at it at an angle, the high points obscuring the low points them behind them, creating the appearance of 3D. the height data for each pixel comes from a texture, or a height map.
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