The Projection section allows the user to choose whether or not each newly created output file should either
use the same projection as the file that it was created from (Use Source File Projection option) or if each file
should use a projection specified by pressing the Projection button. If the user selects to specify an output
projection and they select a zoned projection like UTM or Gauss Krueger, they will have the option on the
projection selection dialog to have the best zone for the center of the output map automatically used if they
select the Automatically Select Best Zone option in the Zone box on the projection selection dialog.
The Setup Gridding (i.e. Tiling) button displays a dialog allowing the user to specify if and how to break up
each file being converted into multiple new files. This option is only available when converting to a raster or
gridded elevation format.
The Setup Sample Spacing button displays a dialog allowing the user to choose to either keep the sample
spacing of source raster and elevation files when converting the selected or to specify a new sample spacing to
resample all of the selected input files at when performing the conversion. This option is only available when
converting to a raster or gridded elevation format.
The Horz Datum selection allows the user to choose the horizontal datum that each newly created output file
should use. By default, each output file will use the same horizontal datum as the source file that it was
created off of. Alternately, the user can specify to have all output files created in NAD27, NAD83, WGS72,
or WGS84 with the appropriate offset being applied automatically.
The Vertical Units selection is present only for some conversions and controls the output elevation units.
The Palette selection is present only for some conversions and controls the palette, if any, used in the output
files. The palette values are defined as follows:
Image Optimized Palette - The palette generated will be an optimal mix of up to 256 colors that will
closely represent the full blend of colors in the source images. This option will generate the best
results, but can more than double the export time required if any high color images are present in the
export set. If all of the input data is palette-based and the combined palette of those files has 256
colors or less, then the combined files of the input file will just be used with no additional export time
Grayscale Palette - This palette consists of 256 scales of gray ranging from black to white.
DRG Optimized Palette - This palette is optimized for the exporting USGS DRG data. The palette
consists of only the standard DRG colors.
DRG/DOQ Optimized Palette - As the name suggests, this palette is optimized for exporting a mixture
of USGS DRG data and grayscale satellite photos (i.e. USGS DOQs). The palette consists of the 14
standard DRG colors with the remaining 242 colors being a range of gray values ranging from black
Halftone Palette - The palette consists of a blend of 256 colors evenly covering the color spectrum.
This palette is the best choice when exporting anything but DRGs and grayscale satellite photos.
Custom Palette from File - This option allows the user to choose a .pal file describing the palette to
use for the export. A .pal file should be a text file with one line per color, with the red, green, and blue
color components for each color in the palette separated by a comma. You can save a .pal file for an
existing palette-based file by opening the Overlay Control Center, selecting the palette-based layer,
press Options, then the Transparent Color button, then selecting the option to save a color palette file.
24-bit RGB - Create a full 24-bit color image with no palette. This will create the best resulting image
but will also take the most space.
Keep Same as Source File - The new file will use the same color encoding as the source file, either
palette-based, 24-bit RGB, multi-band, or grayscale.
Global Mapper User's Manual
Map GPS Coordinates - GPS Map Coordinates - GPSCoordinates Map