Artemis BP00707, Руководство пользователя

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5.7 Entering Mission Marker Coordinates
In addition to importing markers from external sources (such as Google Earth), Mission
File markers can be entered manually from geographic positions. However, there are
several formats that positions can be expressed in and this section looks at how
Artemis Manager handles these…
5.7.1 Definitions
The terms “Latitude” and “Longitude” define values of a geographic coordinate system
for positions on the surface of a sphere such as the Earth.
 Latitude is the north/south angle between a point on the surface of the Earth and
the equatorial plane, where a straight line that passes through the point and is
normal to the surface of the Earth. Latitudes can lie between -90° (or 90° South) to
+90° (or 90° North), where 0° lies on the equator.
 Longitude is the east/west angle between a point on the surface of the Earth and
the reference meridian that goes from the North Pole to the South Pole. Longitudes
can lie between -180° (or 180° West) to +180° (or 180° East)
1
.
Latitude and Longitude geographic coordinate values represent the value of an arc, and
depending on the convention being used can typically be expressed in one of three
ways…
Degrees
Sometimes referred to as “Decimal Degrees”, the value is written as a single number
with fractional part that describes the coordinate.
Values in degrees are written with a circular dot symbol ( ° ) after the value.
This is the simplest form of expressing a coordinate but requires a significant number
of decimal places to describe a location
2
.
At the equator (worst case), typically 5 decimal places are required to have a precision
of approximately 1 metre, while 8 are required for approximately 1 millimetre.
Degrees and Minutes
The coordinate is expressed as two fields…
 The first field contains the whole (integer) number of degrees, and is indicated
by the circular dot symbol ( ° ).
 The second field contains the number of minutes with an optional decimal
fractional component, and is indicated by the single quote symbol ( ' ).
Each minute value represents one sixtieth of a degree (
1
/
60
), and so the decimal
minutes value can be obtained by multiplying the fraction part of a decimal degrees
value by 60. For example…
32.76125°  32° 45.675’ (as 0.76125

60 = 45.675)
This notation is sometimes called Degrees and Decimal Minutes, or DM for short.
Degrees, Minutes and Seconds
Expanding on the previous form, the coordinate is expressed as three fields…
 The first field contains the whole (integer) number of degrees, indicated by the
circular dot symbol ( ° ).
1
Values of -180° and +
180° describe the same antipodal meridian relative to the 0° “Greenwich”
meridian.
2
For further information on precision visit http://en.wikipedia.org/wiki/Decimal_degrees .