Map GPS Coordinates - GPS Map Coordinates ... - Global Mapper

&ltx-pixel location&gt,&lty-pixel location&gt,&ltx-ground location&gt,&lty-ground location&gt,&ltpoint
name (optional)&gt,&ltpoint error in pixels (optional)&gt
There are also options on the File menu for loading control points and projection information from an
OziExplorer .map, CompeGPS .imp, and Touratech TTQV .cal files as well as saving your control point
information to world (TFW, JGW, etc.) files.
Options Menu
Global Mapper User's Manual
The Options menu allows you to setup various options related to the rectification process, as described below:
• Rectification Method - the Rectification Method submenu allows you to select which rectification
method (hence the name) to apply to the entered control points. Different methods are available based
on how many control points have been entered. The various methods are as follows:
♦ Automatic - the Automatic select automatically selects the "best" rectification method that is
available based on the number of control points that have been entered. This is the default
method and should rarely need to be changed.
♦ Linear - the Linear rectification method is used when only two control points are entered.
This is the simplest of the rectification methods and is equivalent to supplying a world file for
the image. This method does not allow for any distortion or rotation in the image, but often
works well if the correct projection is selected for the image.
♦ Helmert - the Helmert, or similarity, rectification method requires at least two controls points
to be entered. This rectification method is useful if you need to maintain the original shape of
data after a transformation. This method will only be used if you explicitly select it from the
list of rectification methods.
♦ Affine - the Affine rectification method requires at least three controls points to be entered.
This rectification method calculates a best fit to a simple equation of the control points
entered. This method can account for some degree of rotation and distortion, but not with a
high degree of accuracy. Because a best fit approximation is used, some of your ground
points may move a little in order to minimize the error among all control points.
♦ Polynomial - the Polynomial rectification method requires at least four control points to be
entered. This rectification method calculates a best fit to a more complex polynomial equation
described the transformation from pixel space to ground coordinate space. Because a best fit
approximation is used, some of your ground points may move a little in order to minimize the
error among all control points. If you have 6 or more control points, a second order (N=2)
polynomial will be used to transform the points.
♦ Triangulation - the Triangulation rectification method requires at least five control points to
be entered. This rectification method performs a Delaunay triangulation for the control points
and will exactly preserve the location of each entered control point. Occasionally the
Triangulation method generates some odd results around the edges of the rectified image. If
this happens, try to enter more control points around the edge of the image, or change your
rectification method to Polynomial.
• Resampling Method - the Resampling Method submenu allows you to select how the source image
pixels will be resampled to create the rectified imagery. These setting simply control whether or not
the Anti-Alias Pixels setting is turned on or off for rectified images. This can be changed later in the
Overlay Control Center.
♦ Nearest Neighbor - simply pick the closest pixel from the source image for each pixel in the
rectified image. This can result in some blockiness. This is equivalent to having the
Anti-Alias Pixels setting OFF.
♦ Bilinear Interpolation - performs a weighted average of the four closest pixels in the source
image to determine the color for a pixel in the rectified image. This is equivalent to having the
Map GPS Coordinates - GPS Map Coordinates - GPSCoordinates Map 105