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Textures and Maps MCC 1013- Computer Modelling Learning Objective Materials and surfaces Understanding textures and mapping © Juhanita 2015 Materials and surfaces In the real world, materials or elements have three natural phases: Solid Liquid Gas Each phase has unique properties that define it, and characterize its look. © Juhanita 2015 Materials and surfaces Surfaces in all phases share common characteristics or properties: colour Shininess Bumpiness Transparency etc Materials are also known as shaders © Juhanita 2015 Visual components of materials In the real world, materials have surfaces that determine how much light the material absorbs or reflects. In 3D, materials are definedby several groups of visual properties, like colour, shininess, and transparency, which you can mimic real world or fantasy surfaces. © Juhanita 2015 Visual components of materials Colour Bumpiness Shininess – specular highlights, anisotropic highlights Transparency Luminosity – self-illumination © Juhanita 2015 Colour and Value of Objects An object’s rendered appearance is influence by three different sources of colour and value: Ambient – is the hue an object reflects if it’s not directly illuminated by light source (shadow areas) Diffuse – hue assigned to the object Specular – hue of any highlights that appear on the object © Juhanita 2015 Colour and Value of Objects Colour in 3D is represented in: RGB(Red, Green, Blue) or HSV(Hue, Saturation, Value) values to define a surface colour or you can map a texture or file texture to a material. © Juhanita 2015 Shininess If a surface is shiny it can have highlights, or hard reflectivity values. The less shiny it is, the softer is its reflectivity and less it will reflect other surfaces. © Juhanita 2015 © mcyuen 2008 Anisotropic Highlights These are not round highlights – the specular highlights so far commonly seen. Anisotropic are ecliptical, directional types of highlights seen probably in hair, velvet, brushed metal and the data side of the CD. © Juhanita 2015 © mcyuen 2008 Visual components & materials Bumpiness A surface can appear bumpy or it actually can have displacements in its surface values. © Juhanita 2015 © Juhanita 2015 Visual components & materials Transparency A surface can be transparent or opaque. When ray-tracing a transparentsurface, light rays that penetrate the surface bend, and the light is refracted. © Juhanita 2015 © mcyuen 2008 Visual components & materials Self-illumination Sometimes when light strikes a surface, the surface appears to be lit from within, or it appears to have a glowing halo. © Juhanita 2015 Texture mapping Texture mapping is a method,pioneered by Edwin Catmull, of adding detail, surface texture, or colour toa computer-generated graphics or 3D models. A texture map is applied (mapped) to the surface of a shape. © Juhanita 2015 Mapping The process of assigning material attributes to an object. © Juhanita 2015 Mapping Before textures are applied, all objects in a 3d package have a default plastic appearance, usually gray or in some range of colours. Mapping enables the user to give the object a specific colour, adjust whether it’s shiny or matte, and apply a patternand so on. © Juhanita 2015 © Juhanita 2015 Map Channels © Juhanita 2015 Maps The common ones are: Diffuse maps Bump maps Reflection maps Opacity maps © Juhanita 2015 Diffuse Map Simply said, these maps are generally in Colour and are used to alter the object’s colouraway from that defined by the coloursetting into a pattern or image. © Juhanita 2015 Bump Map Bump maps vary the surface roughnness by manipulating the object’s normals according to a grayscaleimage. Bump maps does not distort the mesh, they adjust the normals’ vector angle. These maps use the light and dark of the map to determine a section’s protrusion, flush and indent. Bump maps are often used in games assets where details are put on the map rather than on the mesh. © Juhanita 2015 Reflection Map These are often knownas ‘environment mapping’ because reflection maps are used to provide an “environment” for the object to “reflect”. © Juhanita 2015 Opacity Map Opacity maps are grayscaleimages that override the material’s transparency settings and allow for an object to vary from opaque to transparent. Similarly, an opacity map uses the grayscale values to control the transparency limits. An example is putting holes in an object without resorting to mesh changes. © Juhanita 2015 © Juhanita 2015 Mapping coordinates Mapping coordinatesare a set of coordinates that specify location, orientation and scale of any textures applied to an object. Similar to the function of coordinates in 3d space, mapping coordinates can affect the map’s orientation accurately and effectively. © Juhanita 2015 Mapping coordinates UVW The mesh coordinate system for mapping is called the UV coordinate system. UVW coordinates can be positioned to provide much more accurate positioning. © Juhanita 2015 Mapping coordinates UVW There are 4 common mapping types for mapping projections: Planar Cylindrical Spherical Cubic © Juhanita 2015 Planar Projection Planar projections are flat, useful for mapping objects like walls, doors or book. © Juhanita 2015 © Juhanita 2015 Cylindrical Projection Cylindrical projections wrap the image around on of the objects’ axes. This may result in a seam which can easily be corrected with some tiling measures. © Juhanita 2015 © Juhanita 2015 Spherical Projection Spherical projections wrap the image around the object in a cylindrical mannerand then pinch the top and bottom closed to surround it. © Juhanita 2015 © Juhanita 2015 Cubic Projection Cubic projections also knownas box coordinates map from six different directions. © Juhanita 2015 Shading Modes There are several different shaders. Someare named for what they do; others are named for their creators. © Juhanita 2015 © Juhanita 2015 Lesson Summary Texture mapping is a method,of adding detail, surface texture, or colourto a computer-generated graphic or 3D model to mimic real world or fantasy surface attributes of materials. © Juhanita 2015 Referrences http://www.3dlinks.com/Links.cfm?categoryid=13&subcategor yid=105&subsubcategoryid=47 http://www.mobilefish.com/tutorials/3dsmax/3dsmax_quickgui de_materials.html Principles of Three-Dimensional Computer Animation, Michael O’Rouke 3d graphics & Animation, Mark Giambruno http://www.mayang.com/textures http://www.3dtotal.com/tutorials/ http://highend3d.com/3dsmax/ © Juhanita 2015 Thank You! And A Very Special Thank You to Ms May Chan for The Content of This Lecture.
