Units of measure are expressed in numerous functions throughout ERDAS IMAGINE. For example, these units are expressed in places such as measuring a line drawn in an image in the View, recalculating elevation values, or if you are looking at the Rectangle Properties dialog of an AOI in an image. This document defines the units of measure used in ERDAS IMAGINE.

Units of measure are categorized into angle, distance, area, volume, and time. For a complete list of valid strings used in the tables below for <units1>, see the file <$IMAGINE_HOME>/etc/units.dat.

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Radian is the standard internal unit used when measuring angles.

| | Conversion to radians <standardunits> | |

| | | |

| | | combination of latitude/longitude degrees, minutes, and seconds converted into a decimal fraction, expressed as degrees |

| | | In latitude/longitude, minutes value converted into a decimal |

| | | In latitude/longitude, seconds value converted into a decimal |

| | | |

| | | 100 grads in a 90 degree angle, 1 grad = 0.9 of a degree or of a radian. Measurement of an arc in metric system. |

| | | Same as grad. The term gon is used in European countries where grad means degree. |

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

<units1> is the expression in Unit column, <standardunits> is the expression derived after conversion.

Example: 2 degrees = 0.034906 radians (to 6 places)

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Meter is the standard internal unit used when measuring distance.

| | Conversion to meters <standardunits> | |

| | | Basic SI* unit of length or distance |

| | | 100 centimeters = 1 meter |

| | | 1000 millimeters = 1 meter |

| | | 1 kilometer = 1000 meters |

| | | 1 meter = nanometers |

| | | 1 meter = microns |

| | | 1 meter = micrometers |

| | | standard internal unit (meter) or if unit is unknown |

* International System of Units (abbreviated SI from the French name Le Système International d'Unités)

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 25 kilometers = 25,000 meters

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Meter is the standard internal unit used when measuring distance.

| | Conversion to meters <standardunits> | |

us survey feet us survey foot | | <value> * 0.3048006096012192 | 1 meter = 3.2808333 U.S. survey feet |

| | <value> * 0.3048006096012192 | 1 meter = 3.2808333 U.S. survey feet |

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 200 U.S. survey feet = 60.9601 meters (to 4 places)

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Meter is the standard internal unit used when measuring distance.

| | Conversion to meters <standardunits> | |

international feet international foot | | | 1 international foot = 0.3048 meters 1 meter = 3.2808398 international feet |

| | <value> * 0.3048006096012192 / 12.0 | 1 inch = 2.54 centimeters 1 meter = 39.3700787 inches |

| | <value> * 0.3048 / 12 / 72.0 | Intended for map compositions. A measurement unit for font sizes in paper units. |

| | <value> * 0.3048 / 12 / 300.0 | Intended for map compositions. A measurement unit for printer devices. Default assumes a device resolution of 300 dpi. |

| | | |

| | | A unit of length defined to be exactly 5,280 feet. 1 mile = 5,280 feet 1 mile = 1609.3472 meters (to 4 places) |

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 3 miles = 4828.032 meters

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Meter is the standard internal unit used when measuring distance.

| Conversion to meters <standardunits> |

| |

| |

| |

| |

| |

| |

| |

| |

| <value> * 0.30479947153867620 |

| |

| |

| |

| |

| |

| |

international nautical mile | |

| <value> * 0.3047997101815088 |

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 3 fathoms = 5.4864 meters

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Hectare is the standard internal unit used when measuring area.

| | Conversion to hectares <standardunits> | |

| | | 1 hectare = 10,000 square meters. Equivalent to 2.471 acres in the English system. |

| | | Defined as 10 square chains (1 chain = 4 rods or 66 feet) 1 acre = 43,560 square feet 1 acre = approximately 4047 square meters |

| | | Area of a plane surface enclosed by a square with each side 1 mile in length. 1 sq mile = approximately 640 acres |

square nautical mile sqnautical mile | | | Area of a plane surface enclosed by a square with each side 1 international nautical mile in length. |

| | | Area of a plane surface enclosed by a square with each side 1 foot in length. |

| | | Area of a plane surface enclosed by a square with each side 1 meter in length. |

square kilometer sqkilometer | | | Area of a plane surface enclosed by a square with each side 1 kilometer in length. |

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 56 square meters = 0.0056 hectares

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Liter is the standard internal unit used when measuring volume.

| | Conversion to liters <standardunits> | |

| | | Metric unit of capacity equal to volume of 1 kilogram of water at 4 degrees C (39 degrees F) and at standard atmospheric pressure of 760 mm of mercury. |

| | | |

| | | Volume used in liquid measure equal to 4 quarts or approximately 3.785 liters. |

| | | Volume occupied by a cube with each side 1 foot in length. 1 cubic foot = 28,316.8 cubic centimeters |

| | | Volume occupied by a cube with each side 1 meter in length. 1 cubic meter = 1000 liters |

| | | Volume occupied by a cube with each side 1 kilometer in length. |

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 4 gallons = 15.1416472 liters

Conversion column lists the formula to convert a numeric value from your selected unit to the IMAGINE standard internal unit. Second is the standard internal unit used when measuring time.

| | Conversion to seconds <standardunits> | |

| | | Basic SI* unit of time. 1/60 of a minute of time. |

| | | 1 minute = 60 seconds. 60 minutes = 1 hour. |

| | | 1 hour = 60 minutes. 24 hours = 1 day. |

| | <value> * 24.0 * 60.0 * 60.0 | 1 day = 24 hours. 365.25 days = 1 year. |

| | <value> * 365.25 * 24.0 * 60.0 * 60.0 | |

* International System of Units (abbreviated SI from the French name Le Système International d'Unités)

Convert the value <value> from <units1> to the same amount expressed in <standardunits>.

Example: 4 days = 345,600 seconds