What is a Layer?

A Layer, or more correctly a detail Layer, is a group of one or more MapLink Geometry rectangular models (tiles) which represent a defined area within the entire extent of the Map. Many Layers are used to make up a map. As the user zooms or pans around a Map, the view switches between detail Layers. The rules governing which detail Layer is displayed for a given view are determined by the Loading Strategy

The Layer consists of one or more tiles arranged in a regular grid (an exception to this rule is found when including raster images within a layer).

A Layer can be constructed from many different file formats and data sources. The only condition is that all data sources in the Layer must produce data in the same coordinate system so that they can be merged together to form a coherent layer. This may be achieved by applying an input coordinate system transform to the data.

A MapLink Layer has the following properties:

• Geodetic Clipping definition. This will clip the data at the geodetic (latitude/longitude) level before transformation through the output coordinate system held by the Map. It also allows clipping to occur across the International Date Line, if so required.

• Output Clipping definition. This will clip the data to a rectangle in the output coordinate system.

• A set of Filtering parameters. Applied to the layer once all of the data for the layer has been read, the data reduction can reduce the number of points in the layer. This allows high-resolution data to be used to produce a lower resolution layer.

• Vector optimisation. Allows sets of vector primitives to be joined together into a single entity.

• Tiling parameters. The number of tiles to split the layer into.

• Terrain. Allows you to set the maximum resolution for terrain tiles in output coordinate units, and also to restrict the maximum output resolution, and therefore size of a tile to a specific number of points in X and Y.