Usos del quitosan y el pululano.

Figure 4-38 shows a screen for the planning a trek task. The progress/profile bar indicates that a one- hour, three-kilometre trek is planned; when the bar is maximised, the user can slide the trek along the time scale in fifteen minute increments to set a better estimate for trek start-time27.

The track sections are selected by touching any point on the track section and dragging in any direction. The dragging movement allows the device to differentiate between taps on information points and the selection of track-sections. As track-sections are selected, the distance and estimated time values are indicated on the progress/profile bar whether it is minimised or maximised. The time markings on the timescale are set directly above the distance they correlate to on the distance scale to give an appropriate impression of time vs. distance.

Since default values for the trekker’s pace and interests have been set29, the user can switch to this task directly from set trekker profile or from set trekker interests. Since browsing tracks and planning a trek are combined, this criterion affects both tasks. Trekkers are expected to select their intended tracks in the sequence they intended to trek them30. Since time constraints did not permit the development of a track selection scheme that allowed a trek which would involve going to some point and then returning by the same route, there is no provision for trekking the same track twice in the same trek. The trek is assumed to begin from an end (the one that is not attached to the rest of the trek) of the track that is selected first. If only one track is selected, a direction is assumed. While in the trekking task, the direction of the trekker’s progress is monitored and the trek-direction is adjusted by the device; the direction that the user is actually trekking is always considered to be forward and is displayed as such.

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Criterion 29 - the device should present the trekking task only after a plan has been set and should insure that the GPS is active as the task is begun

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Criterion 27 - the device should present the planning a trek task only after the trekker’s profile and interests have been set

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Criterion 26 - the device should provide a planning a trek task which allows the user to indicate the sequence and direction that the tracks will be trekked along with an estimated start time

Track-selection is indicated by reversing the ‘un-selected’ colour scheme. Un-selected track section. Original start-time estimate: 10:00 Current time: 10:55

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4-62 Implementation

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This task is only fully functional if a trek has been planned, the GPS is active and the user is close to or on one of the trek’s tracks. In addition to the information that is available during the prerequisite tasks, the user can see their current position in the region and the on-track distance from their current position to any other information-point on the trek along with the time required to reach that point. During the trekking task, the time estimates are based on the user’s observed walking pace31. In addition, the location-specific information that the user has chosen to be informed about, spontaneously appears as the user approaches the location it is related to32.

FIGURE 4-39 - CURRENT POSITION & HISTORY

As mentioned earlier, the trekking task is only allowed if at least one track is selected; the GPS is activated as trekking begins28. Figure 4-39 shows a screen from the trekking task. Here the trekker’s current position33 and previous positions34 can be seen on the map; here since the progress/profile bar is maximised, the current position can also be seen on the progress/profile bar. The position triangle shows as green when there is a strong GPS signal, as yellow when the signal is weak, and does not show at all when the signal is insufficient for use35. Figure 4-39 also demonstrates the automatic centring of the current-position marker36.

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The viewing information task is actually a sub-task that occurs as part of the browsing tracks, planning a trek or trekking tasks. However, it is implemented as a task on its own. This allows it to employ the entire screen while active37; it also allows the user-task switching mechanism to be used to switch back to the task that caused it to be displayed. Since the information only needs to be displayed while it is

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Criterion 34 - during ‘trekking’, all time estimates should be based on the user’s observed walking pace

32

Criterion 35 - during ‘trekking’, the device should cause information that is of interest to appear spontaneously as the trekker approaches the location to which it relates

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Criterion 30 - during ‘trekking’, the device should indicate the trekker’s location

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Criterion 31 - during ‘trekking’, the device should indicate the history of the trekker’s location

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Criterion 28 - the design should gracefully deal with GPS dropouts

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Criterion 18 - the device should enable the user to modelessly pan the map. During ‘trekking’, the device should also, over time, centre the map at the trekker’s current location

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Criterion 36 - the device should display location-specific and region-specific information in the largest format that can be supported by the device

Solid black dots indicate previous positions.

Triangles indicate current position on map and profile.

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Implementation 4-63

actively being viewed by the user, using the entire screen for viewing information does not have a significant impact on the other tasks’ access to the screen.