See also Part 2 and Non periodic tiling
In many texturing applications it is necessary to be able to "tile" the texture over a larger region than the texture segment covers. In the ideal case the texture segment automatically tiles, that is, if it laid out in a grid it forms a seamless appearance. For example consider the following texture.
Many textures of tiles form such seamless surfaces easily because they are naturally bounded by rectangular discontinuities. For example consider the tile
Laid out it forms the tiling below
Other regular tiles fit together in more subtle ways.
For texture segments that don't have strong directional structure a common tiling method involves mirroring each second segment so that adjacent edges match, this is illustrated below
and here in a real example
This larger segment can now be repeated in the normal way indefinitely as all the edges will now join without discontinuities. Sometimes a mixture of mirroring and direct tiling can be applied, that is, mirror tile in one direction and do a straightforward tile in the other direction.
