The Sonar Viewer

The sonar viewer is part of the Track edit window, and displays sonar recordings for tracks that have been imported from compatible sonar log files. All available channels can be viewed, either together or separately, and recordings can be replayed at speeds of up to 30x.

ReefMaster processes sonar log files on import to create indexes into the sonar recording. Tracks imported prior to version 1.5 of ReefMaster will need to be reimported before they can be viewed in the sonar viewer. ReefMaster does not support viewing of Lowrance SLG sonar recordings made using the "low quality" setting.

Using the Sonar Viewer

The sonar viewer display is opened by clicking on the Sonar button (1) within the track edit area. If the sonar button is disabled, then there is no compatible sonar recording associated with the track. Possible reasons include that the track in an SLG file recorded with the Low Quality setting, or that the option Use SLG2Txt.exe was selected in the GPS Equipment Profile used when importing the track.

The sonar viewer display consists of the main display area (4), which consists of separate display areas for each sonar channel. Display options for individual sonar channel displays can be accessed by clicking the settings button within the channel display (5). The sonar control toolbar (3) controls the sonar viewer layout, as well as providing functions that apply to all sonar channel displays. The Mouse Mode Selector in the track view (2) is used to select the mouse operations that take place within the sonar channel displays.

The Sonar Control Toolbar

(1) Sonar Channel Selector

The sonar viewer can display Primary (1), Secondary (2), Downscan (DS) and Sidescan (SS) channels, in any combination. Primary and secondary channels are conventional sonar channels; typically the primary channel will be around 200khz, whilst the secondary channel will be a lower frequency that is more suited to deeper water.

·The visibility of a sonar channel can be toggled by clicking the appropriate button.

·Not all channels will be available for all sonar logs; buttons for any channel(s) that are not available will be disabled and cannot be selected.

·The relative size of the sonar channel displays can be adjusted by dragging the horizontal and vertical spliiter bars (1, 2).

(2) Playback controls

The playback controls are used to control sonar playback. Start playback by using the Play button and stop playback using the Stop button. To adjust playback speed, click the Fast Forward button and select a playback speed using the slider control. Playback will begin automatically when the playback speed is adjusted.

The current time position within the sonar recording is shown. This position relates to the most recently displayed sonar ping, in the same way that a boat's position relates to the sonar pings that are currently being received. For 2D sonar, this is the right hand edge of the display and, for side-scan, the top edge.

(3) Show boat position and data panel

Click the boat button to show the current position in the track as a boat icon within the track view. A data panel is also shown at the top left of the sonar display, showing latitude, longitude, heading, speed and depth.

When the boat position is shown, the centre of the track-edit area remains locked to the current sonar position.

(4) Image snapshot

To take an image snapshot, click the Image Snapshot button. Images can either be saved to a file (high quality JPG) or copied to the clipboard, from where they can be pasted into other applications, such as a word processor or email. A data panel containing position and depth information can also be exported; to export the image without this data panel, uncheck the option Include data panel.

(5) Position scroll bar control

Drag the position scroll bar to move the displayed position within the sonar log. Note that all channels move together.

Sonar Channel Displays

Each sonar channel is displayed in a separate window within the sonar viewer display.

Settings for each channel can be accessed by opening the channel settings toolbar, by clicking the settings button located within the channel display. For 2D sonar channels (primary, secondary and down-scan), the settings button is located at the bottom left of the display (1). For the side-scan channel, the settings button is located at the top right of the display (3), so as not to interfere with the depth scale.

The 2D channel display can be scrolled vertically by using the vertical scroll-bar at the right of the display (2), whilst the side-scan display can be scrolled horizontally by using the horizontal scroll-bar at the bottom of the display (4). Scroll-bars a hidden until the mouse pointer is over the channel display.

The time position is adjusted using the scroll-bar in the Sonar Control Toolbar (see above) and applies to all channels.

The display can be zoomed by using the mouse-wheel, keyboard + and - keys, or the zoom-box mouse mode (see below).

Mouse Operations

The Mouse Mode panel in the track view also controls the operation of the mouse within the sonar viewer.

In addition to the operations described below, Fit Limits (vertical or horizontal, for 2D or side-scan) can be activated at any time by double-clicking in the display, and the view can be panned by clicking with the middle mouse button whilst in any mouse mode.

(1) Select

When in select mode, clicking within the sonar display selects the nearest track-point in the track edit window. If track-points are displayed within the sonar display (see below), select mode is used to select and drag an individual track-point. Selecting a track-point within the track edit window will move the sonar display so that the position of the trackpoint is centred horizontally.

(2) Zoom

The sonar display can be zoomed using the standard zoom-box behaviour; draw a rectangle around a region to zoom in. The display can also be zoom by using the mouse wheel or the + and - keyboard short-cuts.

(3) Pan

The sonar recording can be dragged using the left-mouse button, with the mouse in Pan mode. The recording can also be dragged by using the middle button when the mouse is in any mode, by using the horizontal or vertical scrollbars, or using the keyboard arrow keys.

(4) Region Select

This mode mode is not operational within the sonar viewer.

(5) Drop Waypoint

Waypoints can be created by clicking within the sonar display with the mouse in Drop Waypoint mode. A new waypoint is created in the appropriate location, which takes into account distance from the boat when in the side-scan channel.

(6) Measure distance

The horizontal ruler is the Measure Distance tool and works in both 2D and side-scan sonar displays. With the mouse in measure distance mode, click any point within the display with the left button, and hold the mouse button down whilst moving to the required position. A ruler is displayed showing distance and bearing.

(7) Measure height

The vertical ruler is the Measure Height tool that works in the side-scan channel only. The measure height tool is used to estimate the height of an object from the length of the shadow that it creates.

This tree stump is approximately 1.9m high

With the mouse in measure height mode, click the object of interest with the left button, and hold the mouse button down whilst moving the mouse to the end of the cast shadow. The height estimate for the object is shown in the ruler.

The measure height tool can also be used to estimate the depth of objects within the water column (e.g. fish). In this case, the tool should be extended from the object to the shadow cast by the object. The height shown will be the height of the object from the bottom, and the depth of the object can be calculated by subtracting that height from the current depth.

(8) Draw tool

The drawing tool allows track-points to be repositioned by tracing the bottom with the mouse (see below).

The Sonar Settings Toolbar

The sonar display toolbar provides functions to set limits, horizontal zoom and palette, as well as brightness and contrast controls.

Some of the available functions differ between the 2D and side-scan sonar channels.

2D Controls

(1) Show Scale

Show or hide the depth scale at the right of the display. Depth units on the scale are in metres or feet, depending on the global depth units setting.

(2) Show track-points

When Show track-points is selected, track-points from the associated track are displayed within the sonar viewer. The position of the track-point within the sonar display reflects the depth of the track-point as calculated by the originating sonar unit. If the depth is incorrect with respect to the displayed bottom, the track-point can be dragged upwards or downwards to correct it, using the mouse in select mode. Track-points may be easier to see if a black and white palette is selected, as shown in the image above.

Note that for Humminbird sonar logs, it is important that the water salinity and temperature have been set correctly during the import process. If these parameters have not been set correctly, track-points may be shown at incorrect depths within the sonar display. See GPS Equipment Profiles.

Redrawing track-points

Sometimes an area of a sonar log has many depths that are not closely matched to the bottom structure. The Draw tool is a quick way of correcting depth values in this situation:

·Select the Draw tool from the mouse mode selector.

·If track-points were not already displayed over the sonar log, they will be turned on automatically.

·Trace the bottom slowly with the mouse, holding the left button down.

·Track-points will be repositioned to follow the path of the mouse.

(3) Horizontal scale

Adjust the horizontal scale of the sonar display using the pop-out slider. Moving the slider to the right zooms the image in horizontally.

(5) Vertical limits

Click the Fit Limits toggle button (1) to automatically adjust the displayed range to fit the depth range of the displayed sonar segment.

The upper and lower display limits can be set using the two sliders (2). The upper slider adjusts the upper limit, and the lower slider adjusts the lower (deeper) limit.

(6) Palette

The palette can be selected using the palette selector. Only RGB palettes can be used in the sonar viewer. User defined palettes can be created in the Palette Editor in the Global Settings window.

(7) Brightness

The brightness of the sonar image can be adjusted using the brightness slider pop-out.

(8) Contrast

The contrast of the sonar image can be adjusted using the brightness slider pop-out.

Side-scan Controls

(1) Show Scale

Show or hide the depth scale at the bottom of the display. Depth units on the scale are in metres or feet, depending on the global depth units setting.

Note that the side-scan scale shows "distance from transducer" when the image is not being slant-range correct (see below), and refers to "horizontal distance from transducer" when the image is being slant-range corrected.

(2) Vertical scale

Adjust the horizontal scale of the sonar display using the pop-out slider. Moving the slider to the right zooms the image in horizontally.

(3) Horizontal range

Click the Fit Limits toggle button (1) to automatically adjust the displayed range to fit the range of the displayed sonar segment.

The horizontal range can be set using the slider (2), which adjusts both the left and right ranges in tandem.

Palette (4), Brightness (5) and Contrast (6) work the same as for 2D (see above).

(7) Slant range adjust

Slant range adjusting a side-scan sonar image removes the water column and stretches the remaining proportionally, so that objects on the bottom are located at the correct horizontal distance from the boat position.

Uncorrected side-scan image - scale refers to raw transducer distance

Slant-range corrected image - scale refers to horizontal distance from transducer

(8) Automatic gain adjustment

ReefMaster employs a sophisticated automatic gain correction algorithm to equalise the signal return across the full extent of the side-scan sonar range. This automatic gain correction often makes sonar images look much better, and is very useful for locating objects at the edges of the recorded range. The images above all show the automatic gain adjustment in action. The image below shows the same sonar segment without the automatic gain correction.

Right Button Menu

The right-button menu contains a subset of the functions available in the individual channel settings bars, appropriate to the sonar channel in the display underneath the mouse pointer, as well as options to save the current sonar viewer settings and select the mouse mode.

Use Current Settings as Default

Select this menu option to save the current sonar viewer settings as the default for all sonar viewer sessions. Properties such as which channels are displayed, the selected palettes, brightness and contrast are all saved. These options can also be edited in the Global Settings.

The Mouse Tracer

The mouse tracer is a feature that works across all window types, that shows the mouse position in one window reflected as a small circle in all visible windows. In the sonar viewer, the mouse tracer shows the position of the mouse within a sonar display in the track edit area.

Mouse position in sonar reflected in the track edit area

To activate the mouse tracer, click the Tracer button in the application status bar.