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Defining Areas of Interest

You may define areas of interest in GeoExpress by vector overlay or by drawing a single rectangle. GeoExpress enables you to define areas of interest in MG3, MG4 and JPEG 2000 encoding.

Vector overlay support enables you to include multiple areas of interest within a single image.

1. Select a job in the Job List

2. Click the Area of Interest button on the toolbar.

   The Area of Interest dialog box appears.

3. To view the image while setting area of interest parameters, click the Show Image button

Drawing a Single Rectangular Area of Interest

A single rectangle can be used to express an area of interest either as the foreground or background (see Inner and Outer Areas).

You can define a single rectangle either by entering values for offsets or by drawing a rectangle across the image with the Draw Area tool. The Draw Area tool is not accessible unless the image is shown.

To enter numerical values to define a single rectangular area of interest:

1. Access the Area of Interest dialog as described above.
2. Select the User Defined Rectangle radio button.
3. Enter values for the Top, Right, Bottom, and Left offsets.
4. Select other desired parameters and click OK.

To use the Draw Area tool to define a single rectangular area of interest:

1. Access the Area of Interest dialog as described above and click Show Image.
2. Select the User Defined Rectangle radio button.
3. Click the Draw Area icon above the image window.
4. Click and drag on the image to define a rectangle.
5. Adjust the shape and size of the rectangle by clicking and dragging the “handles” at the sides and corners; adjust its position using the middle handle. Offset or other positioning values are automatically filled in.
6. Select other desired parameters and click OK.

Using Vector Overlays to Define Areas of Interest

GeoExpress supports vector overlays of Esri Shapefile (*.shp), MapInfo TAB (*.tab), and GML version 2 (*.gml) formats. Vector overlays must be in the same coordinate system as the input image file and must contain closed polygons in order to be valid. GeoExpress uses all valid shapes within the active layer as the combined area of interest; individual shapes within the active layer cannot be turned on or off.

Area of interest options set by the user apply to all shapes in the active layer.

Vector overlays are not editable within GeoExpress.

To use a vector overlay to define an area of interest:

1. Access the Area of Interest dialog as described above.

2. Select the Vector Overlay File radio button.

   A panel of vector overlay options appears in the middle of the dialog box.

3. Enter a file path in the Vector Overlay File field or click Browse to search your directories.
4. Select an active layer from the drop-down list if necessary. GeoExpress supports only a single layer of a given vector overlay. By default the first layer is taken.
5. Select any other desired parameters and click OK.

To remove a currently listed vector overlay click Remove Vector Overlay File.

If a vector overlay is selected and Show Image is selected, the shapes will be drawn on top of the input image in the image window. Filling in the shapes may give you a better idea of the areas they define by displaying the shapes as solid polygons.

To fill in the areas of interest, select the Fill Shapes check box below the image window.

The outline color for the drawn shapes can be customized by clicking the "Outline Color" button. The line width for the drawn shapes can be set on the Appearance tab of the Preferences dialog box. Changing the outline color and line width has no affect on the resulting encoded image, and is only used for previewing purposes.

NOTE: The use of GML-formatted vector overlays can result in the creation of files with a “.gfs” extension in the directory on your computer where the GML files are stored. These are not used again and may be ignored or deleted.