Texturing is a type of mimesis which creates a detailed surface for a model in 3D animation that simulates the model that will seem tangible and realistic when rendered out. Instead of creating the ‘texture’ of bricks for a modelled wall through moulding and manipulating the model itself, texture mapping can be used in either a 2D format or 3D format to easily convey the surface of bricks. (Ratner, 215)
There are various ways to approach texture mapping. One way is to use 2D texture mapping which requires one to map or wrap a 2D image around the 3D model through the direction and instruction of geographical planar/ UV coordinates in a program. For the brick wall one could take a 2D bitmapped image of a flat image of bricks and coordinate this to wrap around the surface of the model and therefore project the ‘look’ and ‘texture’ of bricks onto the model.
However, each model is different and therefore requires a different type of texturing technique. It is imperative to know which axis and coordinates the object faces and sits along in order to determine what type of projection to use.
One can use planar projections/ mapping which can be seen as projecting the image on the surface using coordinates of the coordinates of x; y and z. These coordinates make up a guide plane for the image to be projected on. This is usually used for flat surfaces such as floors or walls. (tiles, bricks, etc). (Ross, 1)
Cylindrical projections wrap around the object once, and can be used for bottles, or other curved cylindrical objects.
Spherical projections work around the shape of a sphere, by rolling the image around the object most likely a rounded object and close the ends at the top or bottom. (Ratner, 216) An example of this is the flat image of the world map and wrapping it around a globe.
Cubic mapping reflects a square or rectangular mapping shape, project from all three axes. (Ratner 215)
Although 2D texture mapping is still flat and is only a projection, one can use bump mapping to simulate the projection and reflection of light on an uneven texture. It does not affect the geometry but rather gives the illusion of a displacement in the models geometry. This simulation can be used in the example of bricks as it reflects the light off the surface of the image. (Ratner,221)
The advantages of 2D texturing are that any image may be used for projection which gives variety. This type of texturing is useful for irregular shapes that require intense UV mapping for differences regarding types of textures. This type of mapping is used more commonly in the industry. (Ratner 215) With processing the data, the images used in 2D texturing are stored in RAM and use less memory for rendering. (Ye & Lewis, 1) It can use bump mapping as a replacement for 3D texture mapping to create an illusion for the displacement of geometry even through it still does no t affect the geometry of the object itself.
The disadvantages of 2D texturing are that sometimes the seams of the images are revealed on the surface as some images projected are too small or the type of projection is unfit for the model. The images can become stretched and therefore the realism is decreased. If it is not stretched, the image must be repeated, and therefore the projection becomes unrealistic. ( Ratner, 215-216)
Unlike 2D texture mapping, 3D procedural texture mapping alters the geometry slightly when applied. It increases the amount of surface detail by applying algorithms by determining their surface colouring and reacting with the noise. (Ye & Lewis, 1) It refers to mathematically generated textures that use a ‘filtered noise function’ that will create spontaneous amplitudes of geometry over the surface of the image. (Ratner 218) 3D procedural textures act like wood or marble as they go on throughout the model and do not just act on a surface level like 2D textures would. If one had to cut out a part of the geometry, one would see an ‘un-textured’ inside of the mesh in 2D texturing, but in 3D texturing the generation would cause the whole mesh to be texture like if one would carve wood, one would see more wood texture. (Okino Computer Graphics, 1). It is created with computer generated simulators, mimicking mostly natural materials (Zhang &Liang, 409)
Most 3D programs come with texture generators as presets that can be altered to fit ones preferences.
The advantages for using 3D procedural texturing are that they are more realistic in the geometric representation of the image as it alters the geometry according to amplitude and so when zoomed in or dollied into the image, the edges can be seen to represent the texture. (Ratner 218) Unlike 2D textures, the texture is not stretched as it is not restricted by the size of an image as it is generated and the randomness of that generation causes it to be unique- no repetition. This also means that the texture is seamless as it is not a projection of an image and no wrapping is required. Only a fraction of memory is used with regards to storage as it is a mathematically generated texture. (Ratner 218) Not only bumpy surfaces are simulated, many types of generations can be found and altered, creating a great variety.
The disadvantages of 3D procedural texture mapping are that the process for the mapping is quite involved and uses many techniques and tweaking to get the image correctly represented. The texture is not as realistic as 2D bitmap images are such as photographs. (Ratner, 218) The generations are limited unlike the 2D bitmap images that offer any type of image needed. The rendering process causes the memory to become intensely large and it is slow to render out because of the processing of the data.
Either way, the type of texturing technique used depends on the model itself and one must consider the advantages and disadvantages of each before deciding on the route to take when trying to represent reality. Trying to find the most efficient way to texture, also ways up with the most realistic representation and obviously personal preference.
Works’ Cited
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