Cutting to the chase
Clearly you don't need a PhD in Computing to sweep in the yard , but one might be usefull in order to know linear and radial sweep algorithm. So , what's all about ? It's just what it sounds it is , sweeping linear ( up to down , for example ) or radial ( making a 360 degrees loop ).
How this can help ? Well...
Suppose you a set of objects in an Euclidean plane. We need to extract information about some objects. The method of linear sweeping takes a line and moves it on a fixed direction. Usually the line taken would be vertical and the direction would be left to right or up to down.
Quite abstract for the moment , huh ? Let's go to a more specific example.
Rectangle union area
This example is well known. You have a set of rectangles with edges parallel to the OX and OY axes. What is their union area.
Well , first of all , let's take a particular case in order to achieve a different perspective. Let's suppose the lower edges are fixed on the OX axis. This would lead us to the following case :
Basically , it would go like that: