Creating 3d Assets for Games
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Transcript of Creating 3d Assets for Games
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Creating 3d Assets for GamesC. Morris - 2013
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Creating 3d Assets for Games
What is an asset.
Any piece of digital media used within a title. This includes:
• Textures
• Materials
• Meshes
• Sounds
• Music
• Animations
• Sprites
• etc ...
We will be focusing on the first three; Textures, Materials and Meshes.
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Creating 3d Assets for Games
Textures
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Creating 3d Assets for Games
Textures overview.
• Textures add detail and context to geometry without changing or adding to it.
• They are however limited in scope.
• Used in more complex material systems to provide more control over how a surface appears.
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Creating 3d Assets for Games
Texture variables.
Use & Context – Helps define other variables:
• Consider where the texture is going to be used. On what kind of surface.
• Textures for complex meshes should be approached differently to those for simple geometry.
• Matching game aesthetics.
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Creating 3d Assets for Games
Resolution – The size of a texture:
• Textures are measured in pixels, normally base 2 , frequently square.
• Dependent on use, must not only fit aesthetic but be related to physical size of mesh it is used on.
• Larger meshes often need larger textures to maintain level of detail.
• Most engines will accept textures as high as 4096x 4096, some will take higher. Standard texture size however ranges between 512 and 2048.
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Creating 3d Assets for Games
Tiling – Does the texture smoothly repeat:
• Textures used on large, uncomplicated geometry are often tiled.
• Tiling is often more efficient as a smaller texture can cover a larger area.
• Texture seams should be contiguous to hide where texture repeats.
• Small areas with a defined shape should be minimised.
• Can result in a less detailed textures, as overly detailed textures can make tiling very obvious.
• Purposefully repeating patterns (such as tiles) can be tiled well as long as each tile is simple.
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Creating 3d Assets for Games
Tiling examples.
Non tiling concrete texture Tiling concrete texture
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Creating 3d Assets for Games
Colour – Does the texture incorporate colour:
• Depending on use some textures work best in monochrome in order to be coloured later.
• Textures can be used in materials (see later) to create effects modulated via colour.
• Monochrome textures do not need to be saved in a colour format, and therefore require less memory.
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Creating 3d Assets for Games
Alpha – Extra data contained within texture files:
• Certain file types save an extra channel known as alpha.
• This extra channel can be used to convey more data in single file.
• Often used to store transparency, or other maps used in materials.
• Files containing alpha channels tend to be larger, but often are smaller than saving another file to convey the information.
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Creating 3d Assets for Games
Materials
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Creating 3d Assets for Games
Materials overview.
• Used to create a more in-depth and detailed representation of a surface.
• Based on shaders, also known as lighting models. Define how light is calculated when it interacts with the surface.
• Affects how a surface is rendered on a pixel by pixel level.
• Use a mixture of different textures and mathematical functions to achieve desired effect.
• Almost entirely replaced textures in modern engines (I.E. You can no longer place a simple texture on a surface, it must be inside a material).
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Creating 3d Assets for Games
Texture maps – Used in combination with shaders to create desired effect:
• Defuse – Imparts colour, shade, tone, contrast.
• Specular – Details areas of high reflectance and shine.
• Normal – Fakes details, such as bumps and dents by modifying the angles used in calculating light reflectance, without adding detail to the model.
• Masks – Maps used to partition areas to allow for differing effects across the surface.
• Bump – Modifies the appearance of the surface by displacing it in 3d space. Normal mapping is a form of bump mapping.
• Baked lighting – Extra maps used to impart more shade and tone relevant to environmental conditions. E.g. Ambient Occlusion and Cavity maps.
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Creating 3d Assets for Games
Texture maps example.
Defuse Normal Specular
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Creating 3d Assets for Games
Normal and Bump mapping (detailed):
• Giving depth to a material without adding extra geometry.
• Shader displaces surface in 3d space on a per pixel basis according to texture map it is provided with.
• Bump maps are normally monochrome maps used to convey height variation.
• Normal maps are full colour maps used to alter the calculated orientation (or normal) of each pixel on a face.
• This method allows for a high level of detail to be displayed on a low resolution model.
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Creating 3d Assets for Games
Normal and Bump map example.
Defuse Defuse + Normal Defuse + Normal + Bump (displacement)
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Creating 3d Assets for Games
Meshes
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Creating 3d Assets for Games
Meshes Basics.
• Meshes are made up of Vertices, Edges, Faces (or polygons), and Surfaces.
• The orientation of any element is known as a normal.
• Most renderers only render the front of faces and not the reverse.
• Normals are used by the shader to smooth the surface.
• Polygons are not limited to a set number of edges. However most engines will only work with Triangular or Quadrilateral polygons.
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Creating 3d Assets for Games
UV maps – Translates between 3d space and 2d space:
• Required to correctly place a texture onto a mesh.
• A 2d coordinate system (UVW) similar to 3d space (XYZ).
• Process saves 3d faces onto a 2d map. Similar to creating a world map, making an item of clothing, or peeling an orange.
• This UV map can then be used as a basis to create textures as the artist knows where the texture will appear on the model.
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Creating 3d Assets for Games
UV map examples.Base model
Final textured model
UV map layout
Final defuse texture
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Creating 3d Assets for Games
Texture baking – Creating textures directly from a mesh:
• Requires a high resolution model, and a low resolution model which will be used in the game engine.
• Lighting effects are applied to the high resolution model, then “projected” onto the game model.
• These lighting effects are then saved using the UV map of the game model.
• Detail from high resolution model now “baked” onto game model.
• Can be used to create many textures from defuse to normal and bump maps.
• Very common workflow uses zBrush to create high resolution models.
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Creating 3d Assets for Games
Texture baking example.
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Creating 3d Assets for Games
Tools & Pipelines
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Creating 3d Assets for Games
Suggested tools :
• Image editor – Creating and editing textures. Photoshop in particular has lots of useful tools including a high degree of brush control, colour control, channels access and an inbuilt library of file type exporters.
• 3d modding application – Creating meshes. 3dmax, Maya, and Blender are all good options
• Digital sculpting application – Creating high resolution models for texture baking. zBrush is the preferred option, but can be difficult to use. Mudbox is a reasonable alternative
• nDo2 – A Photoshop plug-in which is extremely useful in creating complex textures all from within Photoshop. Including creating normal maps from scratch and converting them into other map types such as defuse and specular.
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Creating 3d Assets for Games
Pipelines – The process of importing assets into a game environment:
• Engines have specific requirements for models and textures.
• Research the engine you are using to find the required settings.
• Options to look out for:
• Meshes – Texture coordinates (UV maps), smoothing groups, materials and animations. Y/Z axis orientation.
• Textures – Bit depth, colour, and compression.
• Suggested File types:
• Meshes – FBX, OBJ
• Textures – TGA, PNG, BMP
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Creating 3d Assets for Games
Example UDK pipeline