This is a bit of research I did as part of my diploma thesis which I finished recently. Li-Yi Wei has done some interesting work with tile-based texturing on GPUs using Wang Tiles to avoid texture repetition (http://graphics.stanford.edu/papers/tile_mapping_gh2004/ and a chapter in GPU Gems 2). I developed some extensions to that kind of method, mostly to allow tiles to be laid out in non-regular grids. The diploma thesis is written in German, but I thought someone on these boards might be interested in the methods I tried for tile-based texturing, so here's a short summary. Maybe I'll do a translation of the interesting parts.
The first thing I did was an alternating indentation of tile rows, with some random jitter. This is useful in conjunction with "real" tiles, as can be seen here. Tiles are used mirrored and rotated as well, and vary in brightness.
Then I tried to implement a decal layer with tiles, which might be useful for mass decals. The decals can be positioned freely, but there's kind of a border around them so they can't be close to each other, or even overlap. Here's an example image that shows flowers as a decal layer on top of a repeating grass texture. As you can see, the flowers are not arranged in a grid. I'm not an artist, so excuse the poor choice of textures
Maybe the most useful technique I developed is using tiles of different widths. This allows textures with proportional font text to be created on-the-fly, with very high resolution. If you want to have readable book or newspaper pages, labels, etc., this can save a lot of memory. Here's an example with text, but this technique is also useful for other kinds of surfaces, like a brick wall. The placement of the bricks isn't perfect here, but that can be improved easily (just a content question). I think it still shows very well what kind of irregular textures you can achieve with only 15 small tiles/bricks.
The first thing I did was an alternating indentation of tile rows, with some random jitter. This is useful in conjunction with "real" tiles, as can be seen here. Tiles are used mirrored and rotated as well, and vary in brightness.
Then I tried to implement a decal layer with tiles, which might be useful for mass decals. The decals can be positioned freely, but there's kind of a border around them so they can't be close to each other, or even overlap. Here's an example image that shows flowers as a decal layer on top of a repeating grass texture. As you can see, the flowers are not arranged in a grid. I'm not an artist, so excuse the poor choice of textures
Maybe the most useful technique I developed is using tiles of different widths. This allows textures with proportional font text to be created on-the-fly, with very high resolution. If you want to have readable book or newspaper pages, labels, etc., this can save a lot of memory. Here's an example with text, but this technique is also useful for other kinds of surfaces, like a brick wall. The placement of the bricks isn't perfect here, but that can be improved easily (just a content question). I think it still shows very well what kind of irregular textures you can achieve with only 15 small tiles/bricks.