In the project Options dialog box, you can add unit formats to your project that are different from your data. After adding alternate unit formats, you can enter them followed by the unit abbreviation in editing tools. These formats are described in the following sections.
You can use alternate unit formats with editing tools only in maps assigned a projected coordinate system. By default, they are set to units defined by the data you are editing.
You can set direction to be interpreted as polar angles or bearing formats.
Polar angles are measured counterclockwise from the positive x-axis starting at zero. Angular values increase in the counterclockwise direction and decrease in the clockwise direction. This is the default setting.
A bearing is a measurement of direction between two points. You can specify a bearing using azimuth or quadrant notation. An azimuth bearing uses the full 360 degrees of the compass to indicate direction. A quadrant bearing divides the compass into four equal sections of 90 degrees.
A quadrant bearing is specified with its meridian origin, north (N) or south (S), listed first, followed by the degrees away from this meridian, and then the direction of the angle, east (E) or west (W). For example, a bearing of N 25 W defines an angle 25 degrees west measured from north. A bearing of S 18 E defines an angle 18 degrees east measured from the south.
Valid input formats for quadrant bearing values include the following:
- [N or S] dd.dddd [E or W], where dd.dddd is typed as decimal degrees.
- [N or S] dd-mm-ss [E or W], where dd-mm-ss is typed as whole degrees, minutes, and seconds with hyphen separators.
This format requires Direction Units to be set to Degrees Minutes Seconds.
- dd.dddd-[1 or 2 or 3 or 4], where dd.dddd is typed as decimal degrees followed by a hyphen (-) and one of the following numeric codes:
- 1 = NE
- 2 = SE
- 3 = SW
- 4 = NW
In the north azimuth system, the azimuth of a line is the horizontal angle measured from a meridian to the line, measured in the clockwise direction from north.
In the south azimuth system, the angles are measured clockwise from south.
You can set angular units to be interpreted as degrees, radians, gradians, or gons.
One degree represents 1/360 of a circle. Fractions of a degree are represented as decimal values. This is the default setting.
Degrees, minutes, and seconds (DMS)
This is the same as degrees except that fractions of a degree are represented in minutes and seconds, where one minute equals 1/60 of a degree and one second equals 1/60 of a minute.
Valid input formats for degrees/minutes/seconds include the following:
A radian is the ratio between the length of an arc and its radius. It is the unit of angular measure used by the International System of Units (SI). 1 radian = 180/pi degrees or approximately 57.296 degrees. There are 2pi radians (approximately 6.28318) in a circle. The length of a circular arc with an angle of one radian is equal to the radius of the arc.
Gradians and gons
Gradian and gon units can be used interchangeably. One gradian (or gon) equals 1/400 of a circle.
The term gon is primarily used in German, Swedish, and other Northern European languages where grad means degree.