| More
on
Defining Waypoints, Tracks, and Routes |
| Types of Points |
| There are waypoints,
trackpoints, via points, points of interest, events, icons,
cities,
exits, etc. They all have at least a two dimensional
coordinate -
latitude/longitude, easting/northing, etc. - because they
are all
geographic locations. Some will have the
elevation too. They are defined by the role they play
and the
attributes they have. |
| |
| Waypoints |
| Besides the coordinates (2D or
3D)
waypoints have a name and usually a symbol (airport, square,
dot,
stadium, bridge, flag, building, bus stop, etc.).
Waypoints may
also
have a color for the symbol and/or name text, how to
display, depth,
proximity distance (for proximity alarms), and a text field
(comment,
message, description). Waypoints stand by themselves - are independent of other points. The user usually creates waypoints either by marking a location with the GPS receiver or by using a map (preferably with mapping software on a computer). Waypoints are shown as a "point" on either the receiver’s screen or the computer screen. The "point" can be some sort of symbol (icon) to represent the type of location. The GPS receiver usually has a section of memory reserved for waypoints (user area memory). It will generally hold about 500 or 1,000 points. Waypoints in the Garmin models usually have 10 character waypoint names. The Garmin 76 series receivers have 16 character comment fields; the eTrex series does not have the comment field. The GPS V has a 15 character name and a 50 character comment length. The older Garmin models such as the 12 series have six character waypoint names. Waypoints in the new Garmin models (not the 12 series) support elevations. Most Magellan receivers have 8 character names and the Meridian series will store 500 waypoints in the internal memory (external memory available in SD cards). Only 200 of the 500 waypoints can have 30 character length comments. The Lowrance iFinder has a 20 character waypoint name and no comment field. Waypoints in the iFinder support elevations. Keep in mind that long waypoint names take a lot of screen space (they will cover up background information and conflict with each other). Also note that screens on handheld GPS receivers are small. |
| Points of Interest |
|
It goes without saying that POI's are also points and are generally supplied by the manufacturer. They have a different name (not called waypoints) because they are stored in a different memory area than waypoints and may have more memory allocated per point for longer names and additional information such as addresses and phone numbers. The "searching" function in the GPS receiver is a bit different for the different types of points. The "searching" function may be done by category in the GPS receiver (and the manufacturer's supporting software). The manufacturers haven't supplied software for users to make their own POI's. And it's unlikely the manufacturer's supporting software will let you edit the POI data to make corrections or additions. However; like uploading maps, there is a user effort to write software programs to allow users to upload their own POI's. On the Garmin GPSmap 76 with some Metroguide version 4
data
loaded and some Topo data loaded, the "Points" menu
consists of: "Waypoints", "Points of
Interest", "Cities", "Exits", "Addresses", and
"Intersections".
"Points of Interest" is further subdivided into: "Food & Drink",
"Lodging",
"Attractions", "Entertainment", "Shopping", "Services",
"Transportation", "Emergency & Govern", "Manmade
Places", "Water
Features", and "Land Features".
And the subdivisions may also be further divided. For
instance
"Food & Drink" is subdivided into: "All Types", "American",
"Asian",
.... "Fast Food", .... "Pizza", .... "British Isles",
"Other"
POIs are either built into the receiver or transferred to the receiver from the manufacturer's software. You don't transfer POI's from the receiver to your software. Waypoints can be transferred both ways. A GPS receiver that only supports 1,000 waypoints can have hundreds of thousands of POIs. |
| |
| Lowrance Icons or Events |
| Icons are graphic symbols used to mark locations like
waypoints but don't
have names. They can be navigated to like waypoints
(use the map
cursor not the menu) but don't store as much information as
waypoints. |
| |
| Routes |
| A route is a set of waypoints that you "tell" the receiver you want to navigate from one point to the next. It is similar to a track but is made up of waypoints instead of trackpoints and only consists of a hundred or so waypoints (depending on the receiver) whereas a track can have thousands of trackpoints. A GPS receiver has specific functions for navigating a route. Since a track and route are similar, newer receivers are getting functions for navigating a track. Since trackpoints don't have names and waypoints do, navigating a track means messages like "approaching turn 14", "approaching turn 15", "approaching turn 16", etc. Navigating a route means that you can get messages like "approaching BEAR-CREEK", approaching JCN-PINE-CK", approaching TAYLOR-PAS", etc. A route is not intended for drawing linear features on the map screen. |
| |
| Tracks and Trackpoints |
| The receiver usually records
trackpoints as you travel. The trackpoints define a
track formed by connecting the points with lines. The
"track"
would represent the road, trail, path, etc.
that you followed. Curves are formed with
short line segments. The GPS receiver
draws your track on the map screen with lines defined by the
trackpoints and a
mapping program (with GPS support) draws your track on the
computer
screen (with or without background maps). The purpose of
trackpoints is to define lines for forming two dimensional
("linear")
features. In general trackpoints don't have names or symbols. They may have a date/time stamp that allows the speed to be calculated for the track segment (track leg - line connecting two trackpoints). The distance is calculated from the location coordinates. The elevation is often recorded too so it's possible to get an elevation profile for the track or a 3D view of it along with average speeds, time, and total distance, etc. depending on the computer program or capabilities of the receiver (don't expect much from the receiver). With some computer programs you can draw a "track" and transfer it to the GPS receiver for a road or trail map or coast outline, etc. The Lowrance iFinder does not store a date/time stamp or elevation on trackpoints. |
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| Copyright © 2003 Dan Anderson. All rights reserved. | |
GARMIN, eTrex, AutoLocate, and TracBack are registered trademarks, and MapSource and Personal Navigator are trademarks of GARMIN Corporation or GARMIN Ltd.
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