Introduction:
It is assumed that mapping is conducted with a data dictionary. It is possible to collect positions without using a data dictionary, but features (points, lines and areas) can not be specified and attribute data can not be collected - mapping without a data dictionary is not recommended. It is also assumed that the section on GeoExplorer Configuration has been reviewed. Under normal circumstances most data dictionaries would contain point, line and area features - mapping of each kind of feature is treated separately here (note: some procedures are common to mapping of points, lines and areas - see Mapping Point Features for these common procedures). It would also be usual for a single mapping project to use several rover files; for example, mapping could be temporarily halted for a lunch break or because PDOP values are too high - in these circumstances the rover file would be closed and a new file opened after the break - closing the rover file also enables the GeoExplorer to be turned off to conserve the battery.

Field Procedures: Line Features

See the page "Mapping Point Features" for information on "Checking GPS Status" and "Opening A Rover File" - both these procedures must be completed before line mapping can commence.

Selecting A feature
Once the rover file is opened, a list of options appears; choosing the option select feature brings up the list of features in the data dictionary:

Figure 1. The Select Feature Screen.

When the required line feature is selected (for example, trail), that feature is "opened", meaning that positions for the feature begin to be recorded. You must be positioned at the beginning of the line feature when recording starts and then walk (or drive or fly or boat etc.) along the line to the end, where recording is stopped. Pathfinder Office creates the line feature by drawing straight lines between adjacent positions along the line. The number of positions collected is shown at the top right of the receiver screen. The rate at which positions are recorded for line and area features is set under GeoExplorer Configuration (usually 1 position every 5 seconds). If you are walking along a line feature, it is common to pause position recording so that attribute data can be entered (see below).

Entering Attribute Data
Selecting a feature also brings up a list of attributes for that feature. Attribute data can be entered while the receiver is recording positions for the line feature. Use the up-arrow or down-arrow to scroll to the desired attribute; selecting the attribute allows values to be entered. For example, selecting the menu attribute "Surface" might bring up the list of menu items "Dirt", "Wood Chips", and "Blacktop" - one of which could then be selected; selecting the numeric attribute "Width" allows you to enter a numeric value (use the left-arrow and right-arrow to move between units, tens, hundreds etc. Use the up-arrow and down-arrow to change digits - when the number is correct, use the selection button to enter the value. The same technique is used to enter characters in text fields). Because entering attribute data is obviously difficult when walking, Pause can be selected to temporarily halt recording of positions - you could then enter attribute data; selecting Resume begins recording again. Note that if the attributes of a line feature change, each segment should be mapped as different line feature - for example, a trail with a surface that changes from blacktop to wood chips and then back to blacktop, would have to be mapped as three different end-to-end line features.

Nested Features
If you select a line feature on the select feature screen (Figure 1), the options list will include nest feature. This option allows you to map a point feature located within a line feature (for example, the line feature bike trail might have the point features stop sign, road crossing, water fountain and rest stop located within it). Nest feature allows you to map the point feature and its attributes in the usual manner (see Mapping Point Features), when finished, the GeoExplorer goes back to mapping the line feature.

Closing The Rover File
When you have mapped a line feature, selecting close feature closes the feature and returns you to the select feature screen (Figure 1). You can then move to the next line to be mapped and repeat the process. When all required features have been mapped, selecting close file closes the file.