The **Unit Converter** dialog provides
quick conversion between units and values used in coordinate system parameter
boxes.

Launch the Unit Converter dialog by pressing the 123 button next to a parameter in the Coordinate System dialog or next to the Local Scale or Local Offset boxes in the Coordinate System Metrics dialog, and then choose Unit Converter.

<unit> |
Choose the unit of measure to be converted into the unit of measure used by the coordinate system. |

Original |
Specify the number of units selected to be converted. |

Result |
The converted value, in the units used by the coordinate system, of the specified number of units to be converted. |

OK |
Apply the converted Result value to the box for which the Unit Converter dialog was launched. |

We are working with a coordinate system, such as Orthographic, which uses meters as the units. The metadata for the data set we are using specifies we must use X and Y local offsets of 200 US Survey feet. We need to convert that value in US Survey feet into the equivalent number of meters.

We press the Unit Converter button next to the Local offset X box.

In the menu we choose **Unit Converter**.

The dialog launches with **Meter**
as the unit. From the long pull down list in the uppermost,
units box we choose **US Survey
Foot**.

We enter **200** into the **Original** box. The dialog
automatically converts that into **60.960...**
meters in the **Result** box.
We press **OK**.

The Local offset X box is automatically populated with the computed
result value of **60.960...** meters.
If we want the same offset in the Local offset Y box
we can either repeat the above procedure for the Y box or simply copy
and paste the value from the X box.

**Metrics values** - Choosing a
coordinate system in the main **Coordinate
System** dialog will load the Coordinate System Metrics parameters
with the correct values for the chosen system. Those are usually based
on a unit of 1 meter or 1 degree, but some national coordinate systems
use values like 0.9 meter. Custom values as read from a world file or
entered manually will also appear.

**EPSG and SRID Overrides** - EPSG
and SRID coordinate systems use a numeric code to identify the coordinate
system. Metrics for EPSG and SRID coordinate systems are applied
as overrides. This allows keeping the coordinate system definition as
a code for readability and for easier conversion.

Assign Initial Coordinate System

**Favorite
Base Coordinate Systems**

**Example:
Assign Initial Coordinate System - **Use the **Contents pane** to manually assign
an initial **coordinate
system** when importing from a format that does not specify the
coordinate system.

**Example:
Change Projection of an Image** - Use the **Change Coordinate System**
command to change the projection of an image, raster data showing terrain
elevations in a region of Florida, from Latitude / Longitude to Orthographic
centered on Florida.

**Example:
Adding a Favorite Coordinate System** - Step by step example
showing how to add a frequently used coordinate system to the Favorites
system.

**Example:
Detecting and Correcting a Wrong Projection** - A lengthy example
exploring projection dialogs and a classic projection problem. We
save a drawing into projected shapefiles and then show on import how a
projection can be quickly and easily checked and corrected if it is wrong.

**Re-Projection
Creates a New Image** - Why changing the projection of an image
creates a new image.

Latitude and Longitude are Not Enough