This picture was made for a friend’s birthday. There are spirals in garter stitch short rows disconnected by black lines

This is no pattern but a technique or method. If you want to learn it, go to Heidrun’s Ravelry Swing-Knitting-Site where you can buy tutorials.
The different color fields are knit with a special algorithm. That means: the short rows are shortened in various intervals. Those intervals are combined in a code. The code is developped before starting to knit and will never change until you finish the picture.