Anishinaabe Arcs: Tutorial 2: arc coordinates
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When laying out the holes for building with arcs, the Anishinaabe would often use a grid. For example when building a wiigwam, Earl Otchingwanigan uses a traditional technique of starting with a rectangle, and then placing holes about every 1.5 feet. Earl says now he "cheats" by using a tape measure, but that in the old days they would either use a "measuring stick" or elbow to finger length to make sure all the holes were evenly spaced.


In addition to the grid, the wiigwam has two axes. The door typically faces east (this is especially important for a sweat lodge or other religous architecture). In the case of a longhouse the long arcs are aligned along this east-west axis, and the short arcs are along the north-south axis.

In our simulation we will use +X and -X for east and west, and +Z and -Z for south and north. We will also have a "height" axis which is +Y. So this is just what you learned in school about the "Cartesian coordinate system" (named after French mathematician Rene Descartes). Of course the Anishinaabe were using it long before Descartes was born. Why isn't it called the "Anishinaabe coordinate system"?


This arc is centered at X=0, Z=0.

Now we added another arc centered at X=4, Z=0. They intersect in the same plane, like the letter M.
What would it look like if it was X=0, Z=4?