XY Harris Multilayer
Global Mapper v18.1 and later support export of XY Harris Multilayer files. The option is available in the File Export menu under Raster/Image Formats.
The Export XY Harris Multilayer Text File command allows the user to export any loaded data sets to a comma-delimited ASCII file containing color or elevation data for each loaded raster layer.
The first line of the file is a header defined as follows:
X, Y, Longitude, Latitude, <raster file name 1>_R, <raster filename 1>_G, <raster filename 1>_B,..., <raster filename n>_R, <raster filename n>_G, <raster filename n>_B, <elevation filename 1>, ..., <elevation filename n>
<raster filename n> will be replaced with the full path and file name of the raster file that is the source of the color data in the corresponding column.
<elevation filename n> will be replaced with the full path and file name of the elevation values in the corresponding column.
Each valid sample will be represented on a single line as follows:
When selected, the command displays the XY Harris Multilayer Export Options dialog which allows the user to set up the export.
The General options panel allows the user to set up the Sample Spacing, Metadata File Formats and Resampling options.
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.
Metadata File Formats to Generate
Choose from the following Metadata file formats:
- World File
- PRJ (Projection)File
- ESRI .aux.xml Projection File
- ERS (ERMapper Header) File
- TAB (MapInfo) File
- MCF (ublox Position) File
- TXT (Text) Metadata
Neighbor - simply uses the value of the sample/pixel that a
sample location is in. When resampling an image
this can result in a stair-step effect, but will maintain exactly
the original color values of the source image.
Interpolation - determines the value of a new pixel based on
a weighted average of the 4 pixels in the nearest 2 x 2 neighborhood
of the pixel in the original image. The averaging has an anti-aliasing
effect and therefore produces relatively smooth edges with less stair-step effect.
Interpolation - a more sophisticated method that produces smoother
edges than bilinear interpolation. Here, a new pixel is a bicubic
function using 16 pixels in the nearest 4 x 4 neighborhood of the
pixel in the original image. This is the method most commonly used
by image editing software, printer drivers and many digital cameras
for resampling images.
Average (3x3, 4x4, 5x5, and 7x7) - the box average methods
simply find the average values of the nearest 9 (for 3x3), 16 (for
4x4), 25 (for 5x5), or 49 (for 7x7) pixels and use that as the value
of the sample location. These methods are very good for resampling
data at lower resolutions. The lower the resolution of your export
is as compared to the original, the larger "box" size you
(2x2, 3x3, 4x4, 5x5, 6x6 and 7x7) - the Filter/Noise/Median
methods simply find the median values of the nearest 4 (for 2x2),
9 (for 3x3), 16 (for 4x4), 25 (for 5x5), 36 (for 6x6) or 49 (for 7x7)
pixels and use that as the value of the sample location. This resampling
function is useful for noisy rasters, so outlier pixels do not contribute
to the kernel value. Some common sources of raster noise are previous
compression artifacts or irregularities of a scanned map/image.
Maximum (3x3, 4x4, and 5x5) - the box maximum methods simply
find the maximum value of the nearest 9 (for 3x3), 16 (for 4x4), 25
(for 5x5), or 49 (for 7x7) pixels and use that as the value of the
sample location. These methods are very good for resampling elevation
data at lower resolutions so that the new terrain surface has the
maximum elevation value rather than the average (good for terrain
avoidance). This method behaves the same as the average on raster/imagery
layers. The lower the resolution of the export file is as compared to
the original, the larger "box" size that should be used.
Split into Separate Files
Choose to split the output into separate files by putting a check next to "Split Into Separate Files Every", and indicating the maximum number of lines that will be in each file. The header will be written as the first line in each file.
Use 'No Data' Value
By default, if there is no data at a location, there will be no data written in the associated column. To specify a value to be written to the file in this case, check the box next to Use 'No Data' Value, and type the value to use in the associated input field.