| Mapping Toolbox | |
Display small circles on a map axes
Activation
| Command Line |
Maptool |
scirclui |
Display Small Circles |
Description
scirclui activates the Define Small Circles dialog box for adding small circles to the current map axes.
scirclui(h) activates the Define Small Circles dialog box for adding small circles to the map axes specified by the axes handle h.
Controls
Define Small Circles dialog box for one-point mode
The Style selection buttons are used to specify whether the circle radius is a constant great circle distance or a constant rhumb line distance.
The Mode selection buttons are used to specify whether one point or two points are to be used in defining the small circle. If one-point mode is selected, a center point, radius, and azimuth are the required inputs. If two-point mode is selected, a center point, and perimeter point on the circle are the required inputs.
The Center Point controls are used in both one-point and two-point mode. The Lat and Lon edit boxes are used to enter the latitude and longitude of the center point of the small circle to be displayed. These values must be in degrees. To display more than one small circle, a vector of values can be entered, enclosed in brackets in each edit box. Pushing the Lat or Lon button brings up an expanded edit box for easier entry of long vectors. The Mouse Select button is used to select a center point by clicking on the displayed map. The coordinates of the selected point then appear in the Lat and Lon edit boxes and can be modified. The coordinates appear in degrees, regardless of the angle units defined for the current map projection.
The Circle Point controls are used only in two-point mode. The Lat and Lon edit boxes are used to enter the latitude and longitude of a point on the perimeter of the small circle to be displayed. These values must be in degrees. To display more than one small circle, a vector of values can be entered, enclosed in brackets in each edit box. Pushing the Lat or Lon button brings up an expanded edit box for easier entry of long vectors. The Mouse Select button is used to select a perimeter point by clicking on the displayed map. The coordinates of the selected point then appear in the Lat and Lon edit boxes and can be modified. The coordinates appear in degrees, regardless of the angle units defined for the current map projection.
The Size and Sector controls are used only in one-point mode. The Radius Units button brings up a Define Radius Units dialog box, which allows for modification of the small circle radius units and the normalizing geoid. The Rad edit box is used to enter the radius of the small circle in the proper units. The Arc edit box is used to specify the sector azimuth, measured in degrees, clockwise from due north. If the entry is omitted, a complete small circle is drawn. When entering radius and arc data for more than one small circle, vectors of values, enclosed in brackets, are entered in each edit box. Pushing the Rad or Arc button brings up an expanded edit box for that entry, which is useful for entering long vectors.
The Z Plane edit box is used to enter a scalar value that specifies the plane in which to display the small circles.
The Other Properties edit box is used to specify additional properties of the small circles to be projected, such as 'Color','b'. String entries must be enclosed in quotes.
Pressing the Apply button accepts the input data and displays the small circles on the current map axes.
Pressing the Cancel button disregards any input data and closes the Define Small Circles dialog box.
Define Radius Units Dialog Box
This dialog box, available only in one-point mode, allows for modification of the small circle radius units and the normalizing geoid.
The Radius Units pull-down menu is used to select the units of the small circle radius. The unit selected is displayed near the top of the Define Small Circles dialog box, and all latitude and longitude entries must be entered in these units. Users must also be sure to specify the normalizing geoid in the same units. If radians are selected, it is assumed the radius entry is a multiple of the radius used to display the current map, as defined by the map geoid property.
The Normalizing Geoid edit box is used modify the radius used to normalize the small circle radius to a radian value, which is necessary for proper calculations and map display. This entry must be in the same units as the small circle radius. If the small circle radius units are in radians, then the normalizing geoid must be the same as the geoid used for the current map axes.
Pressing the Cancel button disregards any modifications and closes the Define Radius Units dialog box.
Pressing the Apply button accepts any modifications and returns to the Define Small Circles dialog box.
See Also
scircle1 scircle2 point
| | scatterm | seedm | |
