Figure 4.

Example of summed images and selected locations for six representative sites. Each image covers an area of $2.083°\times 2.083°$. (a) Area near Chicago and Lake Michigan, USA. (b) Region of Argentina with few settlements. (c) Sweden (top left) and the Gulf of Bothnia (bottom right). Here the buffer at the edges prevents the point from going too close to the edge. (d) Highly settled and bright region in the Eastern USA. The selected point is located in the Land Between the Lakes National Recreation Area. (e) Densely settled region in Spain. (f) Area near São Paulo, Brazil.