Marching squares

Marching Squares is a way of taking complex shapes like mountains and valleys and turning them into straight and simple lines. To do this, you imagine a grid of squares on top of the shape. Then, you "walk along" the lines to find the shape. When you march across the grid, you look at each corner of the square to count how many walls are around that point. Based on the number, you can figure out which direction to march and what type of line you'll make. So, the more complicated the shape, the more marching and counting you'll do. In the end, you'll have a bunch of simple straight lines that represent the complex shape!