Map and Frame Limits
The map and frame limits are two related
properties that limit the map display to a defined region. The map latitude and
longitude limits define the extents of geodata to be displayed, while the frame limits
control how the frame fits around the displayed data. Any object that extends outside
the frame limits is automatically trimmed.
The frame limits are also specified differently from the map limits. The map limits
are in absolute geographic coordinates referenced to an origin at the intersection of
the prime meridian and the equator, while the frame limits are referenced to the rotated
coordinate system defined by the origin of the
For all nonazimuthal projections, frame limits are specified as quadrangles
]) in the frame coordinate system.
In the case of azimuthal projections, the frames are circular and are described by a
polar coordinate system. One of the frame latitude limits must be a negative infinity
-Inf) to indicate an azimuthal frame (think of this as the
center of the circle), while the other limit determines the radius of the circular frame
rlatmax). The longitude limits of azimuthal frames are
inconsequential, since a full circle is always displayed.
If you are uncertain about the correct format for a particular projection frame limit, you can reset the formats to the default values using empty matrices.
For nonazimuthal projections in the normal aspect, the map extent is limited by the minimum of the map limits and the frame limits; hence, the two limits will coincide after evaluation. Therefore, if you manually change one set of limits, you might want to clear the other set to get consistent limits.