Open Printable/Searchable Copy - Global Mapper

Global Mapper User's Manual
colors or less, then the combined files of the input file will just be used with no additional export time
being required.
• 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
to white.
• 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.
• Multi-Band Image - The new file will use be a multi-band image using the same number of bands as
the input file. You will be able to choose either 8-bits or 16-bits per band.
The additional list of options varies depending on the particular conversion being performed. The meaning of
those options is defined below:
• Add Watermark Image - when this option is checked, you will be prompted to select an image to use
as a watermark for your raster format export. You will also be allows to select display options for
your watermark image, such as transparency, to provide the desired effect. The selected watermark
image will be stretched to cover the entire output image for each converted file.
• Adjust Image Contrast - causes the contrast of any input file to be automatically adjusted prior to
being exported. This is useful for improving the display of some types of imagery.
• Clamp Export to Lat/Lon Boundary - causes the export bounds of each image being converted to be
clamped to the nearest 3.75' lat/lon boundary. This can be useful in limited cases, such as when
reprojecting to geographic/arc degrees and the source images had a tiny collar to make the image
square in the native projection.
• Convert to Grayscale - causes the exported imagery to be generated in only shades of gray.
• Crop to Selected Areas - this option specifies that each exported file will be cropped to any area
features selected with the Feature Info or Digitizer Tools. If this option is selected, no output file will
be generated for any input file that does not intersect any of the selected crop areas.
• Export Areas, Export Lines, and Export Points - these options respectively control whether area, line,
and/or point shapefiles are generated from the source vector data files. At least one of these options
must be selected.
• Fill Small Gaps in Data - this option specifies whether or not small gaps in the elevation or raster file
being exported will be filled by interpolating between nearby known values.
• Force Square Pixels in Output - causes the newly created files to have square pixels in whatever
projection they are created in. This allows the files to be used with the widest variety of other
software packages, many of which do not correctly handle non-square pixels.
• Generate Projection (PRJ) File - causes a projection file describing the ground reference system of
the output file to be generated for each output file in addition to the output file itself. The PRJ file will
have the same name as the output file with the .prj extension.
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