Coordinate system zones and neatline clipping (Maritime Charting)

There are cases when the area of interest of a grid intersects more than one Universal Transverse Mercator (UTM), State Plane, or other coordinate system zone. In these scenarios, the merging of the grid lines and their ticks is required. This is referred to as converging zones or zippers. For small-scale maps, this effect may be repeated several times across the extent of the area of interest. The zones will start and stop at the zone boundaries.

Creating coordinate system zones

The Grids and Graticules Designer allows you to define coordinate system zones and store them as a grid property. You load polygon feature classes or shapefiles with defined coordinate systems into the Grids and Graticules Designer. These coordinate system zone feature classes define zone boundaries or extent. You can save zone boundary definitions to a grid template.

Coordinate system zone feature classes must have a short integer field that identifies each zone and a text field that stores the spatial reference information in coordinate system or projection file (.prj) text format. A selection rule parameter determines which zone to choose for grid component creation when the area of interest intersects more than one zone or extent. For example, the primary coordinate system of a grid, for an area of interest that intersects UTM zones 10 and 11, is calculated from the coordinate system zones feature class and is based on a selection rule of largest area.

Neatline clipping

Segments can be clipped at coordinate system zone boundaries using settings in neatline properties of the Grids and Graticules Designer. This gives you the flexibility of clipping neatlines and all subcomponents, like segments, gridlines, ticks, and points, to an extent defined in the coordinate system zones feature class or shapefile. Ordinal Rank, a priority ranking, controls clipping. The components must have the coordinate system zone set to indicate which zone they are created over. In the above example, neatlines falling in each UTM zone 10 and 11 can be set to clip to the corresponding UTM zone.