Wk 4: Research

Shaders and textures control how the 3D model will appear visually. In 3D programs, these are applied to the material which is then applied to the model. Sourced from: http://www.informit.com/articles/article.aspx?p=2162089&seqNum=2

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Texture

Overview

Texture refers to the flat image applied to the model that gives it colour, patterns and details (Geig, 2013). Through the process of texture mapping, a two dimensional texture file is laid over the top of the model in order to texture the model. Texturing can range in complexity from simply colouring the model to creating a photo-realistic image (Slick, 2014).

Types of Maps

There are a variety of different texture maps that allows for different outcomes (Reallusion, 2011). Depicted in the image below are some the commonly used maps:

4Sourced from: http://proletariat.com/2013/10/08/building-the-medic/

  • The diffuse map holds the colour detail. This is where a majority of the detailed texture painting will occur (Digital Lighting).
  • The normal and bump maps allow additional shading without having to change the model (Digital Lighting).
  • The gloss or specular map determine the shininess of the object. White areas will be more specular and therefore shinier (Reallusion, 2011).
  • The ambient occlusion (AO) maps are overlaid onto the diffuse map to give soft realistic shading (Digital Lighting).
  • The alpha map determines opacity. This allows for intricate detailing such as hair, as shown below (Reallusion, 2011).

hair (2)

Appearance of Surface

For some surfaces like fur, cloth or rough surfaces with bumps or scratches, it is not feasible to model every single minute detail. Because 3D modelling is such a lengthy process, the artist can use texture maps to “fake” some of the surfaces (McDermott, 2011). The 3D models of the buildings shown below have either a brick surface or smooth surface:

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However, when texturing the artist is able to incorporate digital painting techniques into the diffuse and normal maps in order to give the surfaces minute scratches, dents and bumps.

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Sourced from: http://www.evermotion.org/tutorials/show/7984/making-of-deserted-village

By using textures to give the illusion of surface, artists are able to create photorealistic models with depth, grunge, opacity and details while also being efficient.

Shaders

Overview

Shaders are a set of parameters that outline how the computer should display the surface of the model. According to Slick (2014), the model’s interaction with light, reflectivity, opacity and glossiness are all determined by the shaders. Typically they are included in the 3D modelling program, allowing the creator to simply tweak the shaders until they achieve their goal (Slick, 2014).

The Appearance of Surface

The large variety of shaders available allows the model to be given the appearance of almost every surface. There are three basic types of shaders, which are described below (Geig, 2013).

Diffuse: evenly distributes light across the objects surface, used for surfaces such as skin.

Shader-NormalDiffuseDetail

A diffuse shader is used on a brick cube. Sourced from: http://docs.unity3d.com/uploads/Shaders/Shader-NormalDiffuseDetail.png

Specular: gives the object a glossy or shiny surface, used for surface such as polished metal or water.

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A water surface with a specular shader. Sourced from: http://forum.unity3d.com/threads/specular-water.64593/

Bumped: used in conjunction with a normal map, these give the surface physical details such as bumps, indents or scratches.

shader-NormalBumpedSpecular-0

A bumped shader is used with a specular shader on a brick cube. Sourced from: http://game.ceeger.com/Components/Images/shader-NormalBumpedSpecular-0.jpg

In addition to this, a main colour can be chosen with each shader. This determines the colour of the ambient light that will be shone on the object (Gieg, 2013). Just as a coloured spotlight does not alter a person’s colour, neither does the main colour: it merely lights the object with the chosen colour.

References

Digital Lighting. Types of Texture Mapping. Retrieved from
http://digital-lighting.150m.com/ch10lev1sec1.html

Geig, M. (2013). Working with Models, Materials, and Textures in Unity Game Development. Retrieved from
http://www.informit.com/articles/article.aspx?p=2162089&seqNum=2

Maya Learning Channel. (2011). Applying Shaders and Materials – Part 1. Retrieved from
https://www.youtube.com/watch?v=ugKj2aYiFpI

McDermott, W. (2011). Faking surface detail for mobile assets. Retrieved from
http://the3dninja.com/blog/?p=1453

Reallusion Inc. (2011). Types of Maps. Retrieved from
http://www.reallusion.com/iclone/Help/iClone3/15_Multiple_Channel_Texture_Mapping/Types_of_maps.htm

Slick, J. (2014). Anatomy of a 3D Model. Retrieved from
http://3d.about.com/od/3d-101-The-Basics/a/Anatomy-Of-A-3d-Model.htm

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