When using textures you often get undesired aliasing effects. Especially when using textures containing high contrast areas like brick patterns. To prevent the aliasing, filters and mipmapping can be used. The setting for these filters can be found in the WorldUp Universe Object. The Universe object has the properties that influence the filtering. The Mipmap Mag Filter that determines how textures are enlarged and the Mipmap Min Filter that determines how the textures can be scaled down. When the values of the properties are changed, WorldUp has to be restarted to enable it.
The rest of this document shows the influence of the different filters. The originally used texture looks as follows:
The next to screenshots show the difference between the Nearest and Linear setting of the magnification filter. The linear filter gives less jaggies but can be a bit slower to render. In practice the magnification filter is always set to linear.
Magnification Filter: Nearest (find the nearest appropriate pixel in the texture)
Magnification Filter: Linear (Take an averaged color using the pixels in the texture that are in a 2x2 neighborhood of the center of the pixel used)
In the next screenshots the Magnification Filter is set to Linear. The Minification Filters are changed. By default WorldUp sets this filter to Linear.
Minification Filter: Nearest (find the nearest appropriate pixel in the texture)
Minification Filter: Linear (Take an averaged color using the pixels in the texture that are in a 2x2 neighborhood of the center of the pixel used)
The other minification filters use mipmapping. When using mipmapping the system calculates scaled down textures of the original textures to remove aliasing effects in the distance. These extra textures will cost some more texture memory but can improve the visual quality of the scene a lot.
Minification Filter: NearestMipmapNearest, here you see the witching to the smaller textures when you get more in the distance. This is the quickest filter that uses mipmaps but the result is poor and this setting is seldom used.
Minification Filter: LinearMipmapNearest, this filter adds the linear interpolition of a 2x2 grid on top of the mipmap switching. This gives a good result and is a good and relative quick filter.
Minification Filter: NearestMipmapLinear, here the linear interpolation of the colors is removed, but now the points are not taken from one mipmap (sized down texture), but are combination of two mipmaps.
Minification Filter: LinearMipmapLinear, this is the most expensive but visually the best filter. It interpolates between mipmaps and takes the averaged color in a 2x2 area.