Waypoints

Waypoints

A position format and a datum for presenting the position of each waypoint are chosen by the user. Changing the format or the datum may be made at will, but too many conversions may degrade the accuracy of the data.

The position formats of all the waypoints in a group can be changed in a single operation as described below. The same applies for datums as described below.

Some information that may be relevant for choosing a datum is given below.

The following position formats can be used: 

• DMS for degrees followed by minutes, both as integers, followed by seconds as a floating point number;
• DMM for degrees as integer followed by minutes as a floating point number;
• DDD for degrees as a floating point number;
• UTM/UPS for easting zone number, northing zone letter, easting and northing of Universal Transverse Mercator or Universal Polar Stereographic coordinates.
• one of the available grid systems, either pre-defined or user-defined, with a zone identifier (void for some grids), a easting and a northing (both in metres by default; user-defined ones may be in feet). The pre-defined grids are:
  • BNG: British National Grid
  • BWI: British West Indies grid
  • CMP: Portuguese military maps grid
  • GKK: German grid ("Gauss-Krueger-Koordinatensystem")
  • ITM: Irish Transverse Mercator
  • KKJP: basic Finnish grid
  • KKJY: uniform Finnish grid
  • SEG: Swedish grid.
  • TWG: Taiwan grid.
  More details on these grids can be found below.
• MH Maidenhead locator coordinates: this is a special kind of grid used mainly for specifying the position of radio stations, each smallest subdivision being 5 minutes in longitude and 2.5 minutes in latitude. This means that conversions from other position formats to this one will most probably loose accuracy.

The altitude for a waypoint is given as a (possibly signed) floating point number in metres.

A symbol and a display option are also chosen for each waypoint. GPSMan symbols and display options may not all be supported by the receiver. When GPSMan is aware of this a tilde ~ will appear before the symbol name in the symbols menu. Symbols and display options not supported will be transmitted to the receiver as the default values; if these are also not supported, the symbol will be transmitted as a waypoint dot, and the display option as "Symbol & name". GPSMan will obviously not transmit this information to receivers not supportting it.

A waypoint can be created from the map , if the map has been geo-referenced: see below

The position of a waypoint displayed on the map can be changed there through a menu, as described below.

A waypoint can be created from a track , either as one of its points, or by taking an average of the coordinates: see below.

A waypoint can be created from the waypoints in a group by taking an average of the coordinates: see below.

Clusters of waypoints can be created by giving a group of waypoints to be used as centres: see below.

GPSMan User Manual
©Miguel Filgueiras, mig_at_ncc.up.pt, DCC-FC & LIACC, Universidade do Porto, 2002

Waypoints