Texturing a 3D model with texture maps (which is effectively applying a 2D pixel shader is performed in conjunction with UV mapping and is a method of adding detail, surface texture and colour to an object by applying different types of image maps to either a UV map or the 3D model itself. A shader is a program that performs shading and producing the appropriate colours in an image. Using a pixel shader to apply textures is very effective at allowing near-photorealistic scene to be rendered in real time, as it greatly reduces the number of lighting calculations and polygons needed to achieve the intended look.
This image shows the different texture maps and how they affect a 3D model.
There are many different types of texture maps, each with a different effect, such as:
- Diffuse mapping- the simplest kind of texture map, it wraps a 2D image around the 3D model so it displays flat colours and textures. These maps are used most effectively on UV maps.
A diffuse map of a safe
- Bump mapping– Bump mapping is a resource friendly method of simulating bumps and wrinkles on a 3D object. A bump map is a grayscale image which creates appears to create variations in height to a surface it is applied to without increasing the polygon count. However, if viewed from the wrong angle the illusion of depth will break.
- Normal mapping– similar to bump mapping in that it creates the illusion of texture without deforming the mesh, normal mapping is more advanced due to its use of an RGB image, of which’s colours directly correspond to the X, Y and Z axes of 3D space. This allows it to be more believably viewed from multiple angles.
This image shows the difference between a bump map and normal map when applied and viewed from an angle. The normal map gives a slightly more convincing illusion of depth.
- Specular mapping– specular maps are used to denote a surface’s highlight colour and shininess. The lighter the value on the map, the shinier the surface will appear to be.
3D shaders are applied to the geometry and topology of the model and can also access the colours and textures already applied to it. Most 3D modelling software allow texture artists to easily tweak shader parameters, allowing the modification of how the 3D object interacts with light, like transparency, glossiness, reflectivity and ambient occlusion.
Some examples of the surface effects that can be achieved when a 3D shader is applied to a surface.
Oz, F. (2015). Normal Map vs. Bump Map | Unity Community. Forum.unity3d.com. Retrieved 22 February 2015, from http://forum.unity3d.com/threads/normal-map-vs-bump-map.78622/
Digital-Tutors Blog,. (2014). Know the Difference: Bump, Normal and Displacement Maps. Retrieved 22 February 2015, from http://blog.digitaltutors.com/bump-normal-and-displacement-maps/
Wikipedia,. (2015). Texture mapping. Retrieved 22 February 2015, from http://en.wikipedia.org/wiki/Texture_mapping
Wikipedia,. (2015). Shader. Retrieved 22 February 2015, from http://en.wikipedia.org/wiki/Shader
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