Displaying Grid Lines - GPS TrackMaker Reference Manual

False Northing
In the definition of the User's Grid, it is not necessary to indicate any parallel (latitude), because the origin (point
zero) of the vertical Y-axis always will be the equator line (0º). However, in most cases, the definition of a false
origin of the Y-axis is necessary to best represent the data. Thus, False Easting will be the initial value, in meters,
of the Y-axis on the Equator Line. If the User chooses, for example, the value 500000 meters, this will be the initial
value of the Y coordinate (or Northing) on the Equator Line. Negative Values are supported.
Scale Factor
Maybe this is the most difficult parameter to define. It is a multiplication constant of each coordinate of the User's
Grid, to minimize the deformations due to the Transverse Projection of Mercator. This projection is used in User's
Grid, with a growing scale error of the central meridian for the extremities of the zone. Thus, the Scale Factor
reduces the difference between the scale error of extremities and of the central area of the zone. The Scale Factor
is a number close to 1 (one), and this is the default value. The Scale Factor for UTM system is 0.9996.
Choosing a Waypoint as Origin
The definition of the parameters of User's Grid is not always an easy task, especially when you want to define the
origin point (0,0) in a specific place. To solve this problem, GPS TrackMaker® allows you to choose a Waypoint
to be the origin (0,0), just click on list box. When the Waypoint is chosen, the program will immediately calculate
the parameters of the User's Grid, and the origin will be the Waypoint.
Warnings:
Changing the datum will affect the coordinate values of the User Grid. Use the specific datum of your region.
Even though GPS TrackMaker® allows the visualization of an area of 18º on each side of the central meridian,
the User must use only up to 3º on each side to avoid bigger scale errors.
Adopting the Scale Factor 1 (one), the area next to the central meridian will provide values of cartographic area
and cartographic length relative to the ellipsoid of the datum in use.

9.17 Displaying Grid Lines

Grid lines are horizontal and vertical dashed lines displayed on screen when the option Grid in the button is
enabled.
Grid lines are shown in several Coordinate Systems supported by the program. In UTM and other rectangular
coordinate systems, up to 4 zones can be shown simultaneously. Limit coordinates for each zone are displayed in
red.
The shortcut key <CTRL G> also shows or hides grid lines.
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