3D antialias illustration

This video illustrates the importance of antialiasing in 3D content.
This video has the same 14-second scene rendered 4 times with different settings each time. Pay attention to the annotations.

It is rendered with POV-Ray, but the technique is similar to mipmapping / anisotropic filtering found in 3D display cards.

The video size is 320x240, but I upsampled it with a Lanzos filter to prevent Youtube from reducing the quality too much. There is no audio.

The texture is a wooden plank texture from iStockPhoto.

Explanation of the aliasing effect (and especially the moiré effect): When high-contrast, high resolution graphics are displayed on a low-resolution display, it is not easy to decide how each pixel is to be colored.
Imagine that you have a cross-ruled paper with just a 5x5 grid on it: 5 cells down, 5 cells across. For the sake of exercise, you want to draw a 8x8 checkerboard (as in chess). Each cell of the grid must be completely filled with just one color. How would you do it? It impossible to draw 32 white cells and 32 black cells (of the checkerboard), for your paper grid only contains 25 cells in total. (Analogy: The video game screen contains only 320x240 pixels in total. Each pixel can contain only one color tone at a given time.) The likely end result will be, that you have some cells randomly colored white and others black.
Now, imagine you will have to rotate the checkerboard a bit (say, 20 degrees), and draw it again. What will the result be? Probably the same, except some white cells have changed to black and vice versa. Repeat this process 10 times, and animate the 5x5 grids you have produced, and you've got a full-blown Moiré effect at your hands.
This is because you've done "aliasing": You have decided that each cell has a 1-1 correspondance to _some_ cell in the original checkerboard.
However, if you were to superimpose the 5x5 grid on top of the 8x8 grid, you would notice that each 5x5 grid cell actually coincides with a number of distinct 8x8 grid cells. In fact, every single cell of the paper would coincide with 4 cells from the checkerboard pattern. Antialiasing is when you observe this fact, and fill each 5x5 cell (display pixel) with an _average_ tone of each of the coinciding checkerboard cell (texture pixel). The result will contain various shades of gray rather than just whites and blacks. It is not so crisp, but it is eye-pleasing and realistic.

Produced in September 2007, uploaded in November 2010.

[Bisqwit]

No, the names of those filters are not based on the "grid" size, or filter width. It is based on the mathematical function used to average samples. Linear interpolation, cubic, sinc etc. are all different mathematical functions. Bi- just indicates it is done on two axis.

[emberytp]

Are annotations on this video archived somewhere?

[roguepackets]

Oh, and about that mipmapping: Shouldn't bilinearly filtered textures be mipmapped down when texels are half a pixel instead of an entire pixel in width? Unlike nearest-neighbor textures, they don't begin to look bad until they're half their original size.

[roguepackets]

On somewhat of a side note:
If a 1x1 filtering grid is just nearest-neighbor interpolation, a 2x2 grid is bilinear filtering, and a 4x4 grid is bicubic, then what's an 8x8 grid called?