# GeoRef Layer

This layer allows one to use any image as a map. You will need to tell it how to align the map to a position in the world and the scale of map.

When a new image is selected the values from a World File will automatically be tried to be found. (subject to the setting in )

If you do not know the scale of the map but know the coordinates of both upper left and lower right coordinates, you can enter these coordinates (Lat/Lon only) and then use the Calculate MPP values from coordinates button.

The map once loaded can be repositioned via , which may be easier than trying to edit the raw property values.

## Layer Properties

Configurable properties:

- The map image file.

- X + Y Scales in metres per pixel.

- Rotation (in degrees), clockwise about the upper left corner position.

- Coordinates of the upper left corner of the map (either UTM or Lat/Lon value).

- Alpha. Control the Alpha value for transparency effects using a value between 0 and 255 with the default being 255 for a fully solid image, whereas 0 is transparent.

### Properties

### World File Notes

&appname; does not support "upside down" images, nor does it support the +ve/-ve definitions of the Y-Scale. Instead the Y-Scale is treated as in the direction of the image, thus reading in from a World File the +ve/-ve of the Y-Scale is ignored and -ve values can not input directly into the GUI (simply use the absolute value instead).

There is limited support for reading in skew values. As &appname; uses a single rotation value, this will be derived from the y-skew value and the x-skew is ignored.

## Layer Operations

### Zoom to Fit Map

Automatically set a zoom level to see the entire map coverage.

### Goto Map Center

Center the viewport on this map.

### Export to World File

Opens a file save dialog to save the scale and position information as a World File.