Tracks

The Track Edit Window

GPS track logs (or trails) and sonar logs are referred to as tracks after being imported into ReefMaster. Tracks can be viewed and edited in the Track Edit Window. If the track has been imported from a compatible sonar log file, the sonar recording of the track can also be viewed in the Sonar pane.

Tracks are made up of a number of individual track points, which contain location, depth and time information. Depth and location data from track points is used to generate underwater maps.

To open a track for editing:

·Double click a track or select Edit from the context menu of one or more selected tracks in the in the Asset Library or

·Double click a track or select Edit from the context menu of a selected track in the Global View or

·Check the Open Tracks for Editing After Import option in the Import GPS Assets window when importing tracks into ReefMaster.

The Track Edit Window consists of the Edit Area (1), with standard mouse, map and waypoint tool-bars, and the Edit Pane, with detailed map properties and edit operations. The edit pane can be shown or hidden using the Edit toggle button (circled).

If the track has been imported from a compatible sonar log file, the sonar recording can be displayed by clicking the Sonar button (3). See Sonar Viewer. If the track has not been imported from a compatible sonar log file, the sonar button will be disabled.

See Edit Windows for an overview of the edit window layout and standard tool-bars.

Track Edit Area

The track edit area shows the track as a collection of individual track points.

Track point colours

Track points are colour coded to show the relative depth of the track point within the track. When the default palette is selected, dark blue represents the deepest point of the track, with red the shallowest. As the colour coding is relative, not absolute, the colours of individual track points may change as the maximum and/or minimum depth of the track changes. Relative colour coding of track points makes it easy to see when individual track points have very different depths to their neighbours, which may indicate a bad data point that needs to be removed.

The palette used to display the track-point colours can be selected using the Palette Selector button in the track edit area toolbar.

Selecting Individual Track Points

Individual track points can be selected using the left mouse button, with the mouse in Select mode. Track points selected in the graphical display area also become selected in the Track Point List present in the track edit pane (see below). Individual track points can be deleted through the context menu, activated using the right mouse button.

Cropping and Deleting Track Points

Groups of Track-points can be selected by using the region-select mouse tool to draw a rectangle around the required track points. Selected track-points retain their colours, whilst track points that are not in the selection zone are coloured grey.

Once the selection is complete, a tool-bar is shown with buttons for the operations that can be performed on selected track points. These options can also be accessed via a context menu, activated by right-clicking on one of the selected track-points.

(1) Crop to Range

Delete all track points other than the selected track points.

(2) Delete Track Points

Delete all selected track points. This operation is the inverse of the crop command.

(3) Create New Track From Selected Track Points

Create a new track asset using the selected track points; the current track is not modified as part of this operation.

A new asset window is shown, where a name for the new track can be entered.

This option is useful when, for example, a single large track covers several different areas of interest for mapping. New tracks can be made by selecting each area in turn, and each new track added to a different map project.

The Track Edit Pane

The Track Edit Pane provides detailed information and edit operations for the track.

1. Track Name

The track name can be set here. Asset names can be any string.

2. Track Properties

(1) Cone Angle

The cone angle of the sonar beam from within which the depth is determined.

ReefMaster uses the cone angle when calculating the depths for map generation. Using a cone angle that is approximately the same as the cone angle used to generate the depths in the track is important to maximise the level of detail that can be resolved. Using too large a cone angle in ReefMaster will erode the size of convex features, whilst using too small a cone angle will have the opposite effect.

Use the transducer cone angle specified by the source device as a starting point for this value.

Note, though, that the GPS device may effectively use an angle that is narrower than the stated cone angle when determining depth, so experimenting with smaller values may yield better results.

If the source device is running dual frequencies, use the narrower of the two cone angles.

(2) Keel Offset

A fixed depth offset that is applied to all track points in the track. This depth represents the depth under the water surface of the transducer.

(3) Water Level

The overall depth of the track can be adjusted up or down by using the slider, or entering a value in the text box. The water level is adjusted by creating a single tide point, which is then applied to all points in the track. Note that this function is disabled if tide values have already been set manually.

(4) Time Zone

The time zone of the track can be set using the drop-down list. The time zone only affects how times are displayed, not how they are stored.

(6) Start Time

The start time of the track, which is the time of the first track point. This value is set during import when it is available. If the start time of the track has not been set, or is known to be incorrect, it can be set here. Track points times are represented as relative time offsets from the beginning of the track, and are important for accurate tide compensation. Changing the start time of the track will update the times of all track points within the track.

Track Properties

Read only track properties including depth and geographic range, number of track points and the file from which the track was sourced.

3. Track Point Depth Filter

Track points can be eliminated based on a depth filter, which removes all values lower or higher than specified minimum or maximum values.

Adjust the required minimum and/or maximum values using the sliders (1). The colouration of the track points in the graphical track display adjusts in response. Track points that will be eliminated as a result of the filter operation turn grey. Click the Apply button (2) to confirm the filter operation.

4. Tide

Adjust track point depths according to the state of tide or water level.

When making maps from data gathered in tidal waters or over multiple trips from lakes at varying water levels, track-point depths must be adjusted to compensate.

Water level adjustments can be made either manually, or by using an existing Tide Station.

Tide Adjustment Using a Tide Station

To use a tide offset values from a tide station, select the option Tide Station (1) and then select the appropriate tide station from the drop down list (2). The tide values are shown in the graph area, with the time period of the track shaded grey (circled).

Manual Tide Adjustment

To add manual water level offsets to a track, select the Manual option (1). A graph area is shown, with the time of the track highlighted in grey.

Depth offset values are entered using the edit area (3) at the bottom of the tide information panel. A time and depth are required for each offset. Offsets are added using the Add button (5).

Depth offsets are calculated between the points added using simple linear interpolation. If only a single point is added, then this value is used as the depth offset for all depth points. This can be useful, for example, when entering lake levels, which may vary from track to track but remain static for the duration of a track. A simple way to add a single tide point is the use the Water Level function in the Track Properties section (see above).

Once a depth point has been entered, it appears in the depth point list (2). A depth point may be deleted using the Delete button (4). To update the depth of an existing depth point, select the depth point and modify the depth in the edit area. Press the Add button to commit the change.