irregular tilings and their duals

To get a better idea how the dualization method works we look at the same hexagonal tiling as before. Here is an image, where the triangles of the dual tiling are shaded:

regularStart

Part of a hexagonal tessellation (blue lines) and its dual (red lines). The triangles of the dual are shaded in pale red.

We now add a line to the original tiling. This line passes throughout the tiling and creates new grid-points wherever it intersects grid-lines, cutting them in two. The line is cut up in small parts, each of them becomes a new grid-line. Then the regular hexagons of the grid are cut into irregular polygons. The dual of this tiling has several new polygons. If we place the points of the dual at the center of their corresponding polygons of the original tiling we get irregular tiles, but we can easily see how the original tiling and its dual correspond:

irregCenter

Adding a straight line to the hexagon tessellation gives a new irregular tiling (blue). Its dual (red) gets additional polygons. The tiles are distorted because the corner points of the dual are placed at the center of the corresponding polygons of the tiling.

The dual tessellation of triangles is now cut up in two parts. These part are joined by quadrilaterals. We adjust the positions of the corner points, such that the lines of the dual are perpendicular to the lines of the tiling and that all have the same length. Then we get again equilateral triangles and the quadrilaterals become rhombs:

irregFinal

Adjusting the positions of the corner points results in equilateral triangles and rhombs for the dual tiling (shown in red).

Actually, you can add any line to any tiling to get a new dual tiling, as long as the line does not coincide with a line of the tiling. The tiles of the dual tiling appear in the new dual tiling and rhombs are added. I won’t give you a formal proof, but in the following posts you will find the computer code that does this.

This entry was posted in Quasiperiodic design, Tilings and tagged , , . Bookmark the permalink.

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