Contour View

The Contour View

The Contour View displays the underwater map as contour lines shown on a background coloured by depth, and is where contours can be selected for export to a GPS device or User Map, and an image of the map can be saved to disk for printing or use in Google Earth and other software packages.

The Contour View is selected using the middle of the view icons (1), and is the default view when opening a map project, once a map area has already been defined in the Define Map View. No map is shown in the contour view if a map area has not been defined.

Contour View Toolbars

The Mouse Mode Selector toolbar (2) contains the standard Edit Window mouse modes, while the toolbar at the left of the edit area contains two functions specific to the contour view; the Palette Selector (3) and Export Map Image (4). Both of these options are described in detail below.

Configuring the Displayed Contours

The contour display settings are located in the Map Settings section of The Project Properties Window.

Contours are displayed as Major and Minor levels. Major levels are shown as bold lines with depth labels, minor lines are fainter and do not display depth. Whether a given depth level is displayed as a major or a minor line depends on the current Contour Spacing. When the map is created in vector mode, isobaths are created for the depth-ranges specified by the major contour interval.

(1) Depth display range

Colours for the raster or vector depth backgrounds are derived from the depth relative to the minimum and maximum depths within the current project. The minimum and maximum depth values can be overridden for display purposes by specifying a depth display range.

No range specified versus depth display range of 0 - 25 feet

Using a specified depth display range can be useful when generating multiple maps. If the same range and palette is used in all maps, then the colours for particular depths will be the same.

(2) Contour Grid Resolution

The resolution of the grid used to generate contours, specified in metres. This value can be determined automatically, or set explicitly to the required value. Lower values produce better quality contours with more points within each contour path, but also increase the time taken to generate the map significantly.

Since generating contours is one of the most time-consuming parts of the map generating process, care should be taken when selecting low resolution values for large maps. In practice, it is usually best to leave this setting to Auto, and only generate high resolution contours when required; for example, to export contours to a User Map or GPS.

(3) Contour Intervals

The depth interval between the displayed contour lines.

Contour lines are generated at set depth intervals, defined in feet or metres depending on the global depth unit settings. Contour lines are shown as major lines, drawn more prominently with accompanying depth labels, and minor lines, which are drawn less prominently and without labels.

Major contours can be generated down to a minimum increment of 0.5m or 1 ft, whilst the maximum contour increment is determined by the depth range of the current project. When generating vector maps, isobaths are created for depth-ranges defined by the major contour interval.

To change the major contour spacing interval, adjust the slider to the required value. The spacing of minor contour levels adjusts automatically as the major contour spacing is changed.

Contour generation can be a time-consuming process, so generating fewer contours (using a larger interval) can result in significantly faster map generation.

(4) Minor contour levels

Minor contours are generated between major contours, at an interval that is derived from the current major contour spacing.

Generate minor contour levels

Select this option to generate minor contour levels at the displayed interval. If minor contours are not required, this option should be de-selected to speed up the map generation process.

Range

The generation of minor contour levels can be confined to a defined depth range by using the Range option. Limiting the generation of minor contours speeds up the map generation process, and is useful for producing maps where a high level of contour detail is only required over certain depth ranges.

To apply a range limit for minor contours:

·Select Range.

·Enter the upper and lower depth ranges in the first and second depth fields, respectively.

The Range function is only available when Generate minor contour levels is checked.

Show minor contour levels

The visibility of minor contour lines can be toggled using the Show Minor Contour Levels check box. Toggling the display of minor contours does not require regeneration of the map, so long as minor contours have already been generated.

Note that any changes to contour settings requires the map to be regenerated.

Adding Map Objects to a User Map

Contours, boundaries, isobaths, shorelines and hardness areas can be added to a User Map where they can be further edited and combined with other features, such as tracks and user-defined paths and polygons.

To add items to a User Map, bring up the screen-level context menu by right-clicking with the mouse in the graphical edit area, select option Add to Map.. and select either All components or the required item type. To add the items to a new user map, choose New User Map.. or, to add to an existing user map, choose the required map from the displayed list.

Exporting a Map

Projects can be exported in a wide range of formats, for use in a range of GPS units or further GIS applications.

Map export options are available in the screen-level context menu, which is shown by right-clicking with the mouse in the graphical edit area. See Exporting Map Projects.

Palette Selector and Colours for Lines and Labels

The background palette can be changed using the palette selector, which contains a list of available colour palettes for the contour map background image.

Choose a new palette by clicking on the required palette in the displayed list.

Palettes can be RGB, with colours specified by their Red, Green and Blue values, or AT5, with individual colours specified by a colour code used in Navico GPS systems. The type of each palette is indicated by a tag shown at the right of each palette in the list.

Lines and Labels

Contour and boundary lines, and associated depth labels, can be shown in dark or light colours so that they can be seen easily on different coloured backgrounds.