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nine block
flash mx   october, 2003   j.tarbell
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312 nine blocks
The nine block is a common design pattern among quilters. It's construction methods and primitive building shapes are simple, yet produce millions of interesting variations.

Individual blocks are composed of shapes in a 3x3 grid,

from a set of 16 primitive shapes.

Blocks are radially symmetric, so the shape and rotation for only three grid cells need be specified. These three cells are the center, the edge, and the corner. All other cells can be derived from these three.

To ensure the generative process is complete, and to provide a method of unique identification for each nine block, they are represented by a 14 bit binary number.
The 2 bit rotation values are converted to degrees by a multiplier of 90, so
that a rotation value of 01 would be 90, 10 , would be 180, etc... The 4 bit shape value directly determines the shape graphic from the set. Shape 0000 is , and shape 1110 is .

Enumerating through each number between 0 and 215 (16384), we generate all possible combinations of this system.

Blocks containing rotationally invariant shapes (shapes that appear the same despite rotation) are eliminated so as not to allow duplicates. Thus, the total number of blocks can be calculated by subtracting all eliminated blocks (5568) from the total blocks possible (16384).


nine block

nine block

nine block
nine block
prints available