The Map Axes

When you create a map, you can use one of the Mapping Toolbox™ built-in user interfaces (UIs), or you can build the graphic with MATLAB^® and Mapping Toolbox functions. Many MATLAB graphics are built using the axes function:

axes
axes('PropertyName',PropertyValue,...)
axes(h)
h = axes(...)

Mapping Toolbox functions include an extended version of axes, called axesm. Axes created with axesm share all properties associated with regular axes, and they includes information about the current coordinate system (map projection), as well as data to define the map grid and its labeling, the map frame and its limits, scale, and other properties. For complete descriptions of all map axes properties, see the axesm reference page.

The syntax of axesm is similar to that of axes:

axesm
axesm(PropertyName,PropertyValue,...)
axesm(ProjectionFcn,PropertyName,PropertyValue,...)

The axesm function without arguments brings up a UI that lists all supported projections and assists in defining their parameters. You can also summon this UI with the axesmui function once you have created a map axes.

The figure window created using axesm contains the same set of tools and menus as any MATLAB figure. By default, the figure window is blank, even if there is map data in your workspace. You can toggle certain properties, such as grids, frames, and axis labels, by right-clicking in the figure window to obtain a pop-up menu.

Tips to Working with Map Axes

• You can list all the names, classes, and IDs of Mapping Toolbox map projections with the maps function.

• You can place many types of objects in a map axes, such as lines, patches, markers, scale rulers, north arrows, grids, and text. You can use the handlem function and its associated UI to list these objects. See the handlem reference page for a list of the objects that can occupy a map axes and how to query for them.

• You can define multiple independent figures containing map axes, but only one can be active at any one time. Use axes(obj) to activate an existing map axes object.

• Map axes objects created by axesm contain projection information in a structure. For an example of what these properties are, type

  h = axesm('MapProjection','mercator')

  and then use the getm function to retrieve all the map axes properties:

  p = getm(h)