Overlap Factor

The Overlap Factor applies to both forms of loading strategy. It defines the percentage of the map window that must be covered by the chosen layer.

Consider the following two cases:

Case 1: High Percentage Factor

The map designer is creating a map with an overview layer of the country, and a single layer for each town within the country. The map, when viewed in the runtime application, is to appear 'solid'. That is, when viewing a town layer, the edges of the layer must not be seen as this would lead to white space appearing around the edges of the layer.

For this case, the designer would choose a value of 100%. Therefore the whole map view must be covered by a layer at all times, preventing any layers that do not cover the whole view from being displayed

Advantages:Creates the impression of a 'continuous' map

Disadvantages:The edge of a layer can never be seen

Case 2: Low Percentage Factor

The map designer is creating a map with an overview layer of the country, and a single layer for each town within the country. The map, when viewed in the runtime application, must always show the most detailed layer available, even if only the edge of the layer can be seen.

For this case, the designer would choose a value of 1%. Therefore a layer need cover only 1% of the map view for it to be considered. This allows layers that only just touch the view extent to be considered by the strategy.

Advantages: Allows the edges of layers to be seen

Disadvantages: Lots of white space can be shown around the edge of the layer.