The Export GeoTIFF command allows the user to export any loaded raster, vector, and elevation data sets to a GeoTIFF format file.

When selected, the command displays the GeoTIFF Export Options dialog (pictured below) which displays export options. The dialog consists of a GeoTIFF Options panel, a Gridding panel, and an Export Bounds panel which allows the user to set up the portion of the loaded vector data they wish to export.


File Type

The File Type section allows you to choose what type of GeoTIFF file to generate. The various file types are described below:


When generating a 256 color (8-bits per pixel) GeoTIFF, it is necessary to select a palette indicates what 256 colors will be used to describe the image being exported. The following choices of palette are available:


Sample Spacing / Scale

The Sample Spacing section allows the user to select the grid spacing to use when generating the file. The default value is the average of the grid spacings of all the currently loaded raster and elevation overlays.

If the Always Generate Square Pixels option is checked, the smaller of the specified x and y resolutions will be used for both the x and y resolution.

Selecting Always Generate Square Pixels ensures that the resultant image file will look good even in software that is not able to deal with pixels that aren't square.

To specify the spacing in units other than those of the currently selected view/ export projection, press the Click Here to Calculate Spacing in Other Units button.

TIFF Format Options

If you want to generate a GeoTIFF file corresponding to a particular scale relative to the selected DPI value (see below), you can check the Export at the Fixed Scale option and then specify the scale to use. For example, if you specify a scale value of 25000, each inch in the output (an inch being the number of pixels equal to the specified DPI value) will be approximately equivalent to 25,000 inches on the ground.

The DPI Value to Save in Image option allows you to specify a DPI (dots per inch) value to save in the TIFF header. Some software, in particular graphics editing software, makes use of this value when sizing TIFF files for printout. Specifying the default value of 0 will result in the DPI tag not being saved to the TIFF file at all.


The Compression selection allows you to select what type of compression to use for the selected export file type. The available compression types are as follows:

Make Background (Void) Pixels Transparent:

For 8-bit palette, 24-bit RGB, or JPEG-in-TIFF files, an alpha channel will be added to the created GeoTIFF file to indicate which pixels should be treated as transparent. Note that this will create a larger file and not all applications will support TIFF files with alpha channels.

ADVANCED: Use Tile Rather than Strip Orientation:

The GeoTIFF file will use a tile-based organization rather than a strip/scanline-based orientation. A tile-based orientation has advantages when zoomed in on a layer for display, but can be slower when zoomed further out. By default a tile size of 128x128 will be used, but this can be customized by creating a DWORD registry key value 'HKEY_CURRENT_USER\Software\Global Mapper\GeoTIFFExport_TileSize' with the desired tile size (such as 256 for 256x256 tiles).

Other Options

Save Scale/Elevation Legend/Grid if Displayed

The distance scale, elevation legend, and coordinate grid will be saved to the GeoTIFF file (except vertical GeoTIFFs) if they are configured to show up in the main display.  

Save Vector Data if Displayed

Any loaded vector data that is configured to show up in the main display will be saved to the GeoTIFF file (except vertical GeoTIFFs).

Generate TFW File

A TIFF world file will be generated with the same name as the GeoTIFF file with a .tfw extension. The TFW file is used by software that is not capable of reading the placement of the GeoTIFF file directly from the GeoTIFF header.

Interpolate to Fill Small Gaps in Data:

Any small areas with missing data will be filled in by interpolating the surrounding valid data. This is useful for filling small gaps between adjacent tiles or small holes in elevation data.

Generate PRJ File

A PRJ file describing the projection of the coordinates in the file will automatically be created .

Generate OziExplorer .map File

A .map file describes the location and projection of the data, similar to a PRJ or TWF file. This file is used by OziExplorer and can be read by other applications as well.

ADVANCED: Don't Write GeoTIFF Header

No GeoTIFF tags will be written to the generated file. This is useful for using things like datum specializations that can't be exactly stored in GeoTIFF files, when a PRJ file is preferred