Groups

The GROUP function classifies pixels according to contiguous groupings. Every individual clump of pixels is assigned its own class. There are, however, several ways of going about implementing this algorithm. The default below demonstrates this. In a 'Rook's Case', the grouping function will consider the lower left portion of the box to be a barrier. On the other hand, the 'Queen's Case' method also looks diagonally (just like a queen in chess), and so the lower left portion is considered to be a gap in the box, and therefore the box's interior is grouped with its exterior.

In IDRISI, you switch from rook's to queen's case by specifying 'include diagonals'. Typically, you would only use a rook's case if trying to uncover polygons separated by a single line of pixels.

Try creating other scenarios for the GROUP function.

How do I work this?