A circle chart is a diagram used as guidelines when making circles. It can be used for lighthouses, corner towers on castles, or anytime you need a circle in a square world.If you want to build a sphere or dome, there are several ways you can do this. The first is to create a circular frame that outlines all vertices with the largest circle (see example). After that is complete, you simply fill in the excess area with circles on scale with the layer that it is on.