8. Charts

In this section:

Introduction

The Chart operations are commands executed on folders of schema type Chart, located on folders of schema type Charts.

A Geocap Seafloor project can contain several folders with schema type Charts. These folders are normally top folders in the project.

The Charts folder contains several menu items on the right click menu. The tools for charts are located on the top of the menu, and listed in the graphic below. The functionality of each of the tools is described later in this section.


The Charts folder menu  

The Display Chart data menu

Display Chart data

This command is executed from a folder with schema type Charts and will display the data created in the chart folders (with schema type Chart).
The command can display data of different type, like Polygons, Soundings and Seafloor specified in the the tab part of the menu. The command can turn on and off display of data located in the project folders.

The content of the menu

The upper part of the menu contains the project name and the name of the active folder of type Charts.

The tabs contains the display methods for Polygons, Soundings (points) and Seafloor (DTM).
In addition there is a tab named Display All for displaying all data types by one click.

The standard command buttons:

The Execute button will execute the display.
The OK button will save the parameters in the menu and close the menu.
The Cancel button will close the menu without saving the parameters.

The Display All tab

• Frame: Use this button to turn on and off the display of the Frame polygon for the selected chart(s). Note that this is a direct action button.

• Chart Name: Use this button to turn on and off the display of the name of the selected chart(s). Note that this is a direct action button.

• Boundary: Use this button to turn on and off the display of the Boundary polygon for the selected chart(s). Note that this is a direct action button.

• Soundings: Use this button to turn on and off the display of the Soundings dataset for the selected chart(s). Click the Execute button to perform the display.

• Use same range for all means that the depth colour range should be the same for all datasets.

• Seafloor: Use this button to turn on and off the display of the Seafloor DTM for the selected chart(s). Click the Execute button to perform the display.

• Use same range for all means that the depth colour range should be the same for all datasets.

• Use LOD means that the visualisation technique should be level of details; i.e. effective on large DTMs.

The Polygons tab

• Frame: Use this button to turn on and off the display of the Frame polygon for the selected chart(s). Note that this is a direct action button.

• Chart Name: Use this button to turn on and off the display of the name of the selected chart(s). Note that this is a direct action button.

• Boundary: Use this button to turn on and off the display of the Boundary polygon for the selected chart(s). Note that this is a direct action button.

The Soundings tab

• Soundings: Use this button to turn on and off the display of the Soundings dataset for the selected chart(s). Click the Execute button to perform the display.

• Use same range for all means that the depth colour range should be the same for all datasets.

The Seafloor tab

• Seafloor: Use this button to turn on and off the display of the Seafloor DTM for the selected chart(s). Click the Execute button to perform the display.

• Use same range for all means that the depth colour range should be the same for all datasets.
• Use LOD means that the visualisation technique should be level of details; i.e. effective on large DTMs.

The Charts part

Select which charts to display data from. The selected charts are individial for each tab.

The Show Chart properties button:

Show the properties for all charts in a separate window..

The Scale to selected charts button:

Select to scale the display around the selected datasets. 

The Extract Soundings Menu

Extract Soundings

This command will extract the soundings inside the defined area of the selected chart(s). The extraction will create a Soundings datset in the chart's main folder. The information about extracted number of points and the specified margin are kept in the chart's properties panel.

Note: Any existing data in the Soundings data set will be replaced.

The content of the menu

The upper part of the menu contains the project name and the name of the active Charts folder.

The Margin part:

The Apply Extra Margin parameter:
Specify if the selected points should be found the specified margin size inside or outside the defined chart frame. The size is in meters.

The Survey Data to extract from part:
Select in the list which files to extract from.

The Charts part:
Select in the list which charts to extract to.

The Gridding Chart dialog

Gridding Chart

This command will do the gridding (terrain modelling) of selected points inside the defined area. The result is a terrain model (DTM), which in Geocap will have a schema of type Structured Points.

The command will appear as 4 different names, dependant on the folder schema type it is executed from.

The commands are:

Gridding: Executed from a folder of schema type Generic.

Gridding Chart: Executed from a folder of schema type Charts.

Gridding Files: Executed from folders of schema type Soundings or Single Beam.

Gridding Multibeam Data: Executed from folders of schema type Multibeam.

See the section 4. Gridding survey data for details about the parameters.

Export Chart data

This command is executed from a folder with schema type Charts and will export data items created and stored in the chart folders (with schema type Chart).

The command can export data of different types, like Polygons, Soundings and Seafloor, as specified in the tab part of the menu. The command can export to different format types and to user specified disk locations.

The Export Chart Data Menu

The content of the menu

The upper part of the menu contains the project name and the name of the active folder of type Charts.

The Tab part:

The tabs contains the settings for the export of Polygons, Points, Surfaces and Hill Shade.

The tabs:

- Polygons:

This tab will export the selected data item(s) from the selected chart(s).

Frame: Use this button to export the Frame polygon.

Boundary: Use this button to export the Boundary polygon.

Formats implemented in the menu are: VTK, Shape, ASCII Column, VTK ASCII, Dxf ASCII

- Points:

This tab will export the selected data item(s) from the selected chart(s).

Soundings: Use this button to export the Soundings dataset.

Soundings_Accepted: Use this button to export the Soundings_Accepted dataset.

Soundings_Rejected: Use this button to export the Soundings_Rejected dataset.

Seafloor surface as points: Use this button to export the Seafloor (DTM) dataset and convert from a grid to xyz points.

Formats implemented in the menu are: VTK, Shape, ASCII Column, VTK ASCII, Dxf ASCII

- Surfaces:

This tab will export the Seafloor data item from the selected chart(s).

Formats implemented in the menu are: VTK, Irap Binary, Irap ASCII, VTK ASCII, GeoTiff, Bathymetry Attributed Grid (BAG). 

Invert Z means that the sign (direction) of the Z axis will change from depth to altitude.

- Hill Shade:

This tab will export the Seafloor data item from the selected chart(s).
The hill shade is a image showing hill shade (relief) instead of depths.

The formats implemented in the menu is GeoTiff.

*The Hill shading part *:
- Altitude deg: The altitude of the illumination source is specified in degrees above horizontal.
- Azimuth deg: The direction of the illumination source, azimuth, is specified as the compass direction.
- Z Scale: Is the factor to scale the Z direction compared with x and y.
- Positiv Z-Axis downward: Set checked for depth values and unchecked for altitude values.
- User defined Color: If unchecked, greyscale is used.

The hill shaded image can be exported to a File only, to a File and project (as a HillShade object), or in Project only.

The Charts part:

Select which charts to export data from. The selected charts are individial for each tab.

The Export Format part:

Select which formats to export to. The selected format is individial for each tab.

Polygon and Point formats: VTK, Shape, ASCII Column, VTK ASCII, Dxf ASCII
Surface formats: VTK, Irap Binary, Irap ASCII, VTK ASCII, GeoTiff

The Output File part:

Select where to do the export. The selected location is common for all export.

Filename: Shows the name which will be generated for the files.
If file already exists: The default method is to overwrite any existing files, but it is also possible to make a copy.

Export Contours

This command is executed from a folder with schema type Charts and will export data items created and stored in the chart folders (with schema type Chart).

The command can contours of two types, Contours and Contour Areas, as specified in the menu. The command can export to different format types and to user specified disk locations.

The Export Contours Menu

The content of the menu

The upper part of the menu contains the project name and the name of the active folder of type Charts.

The Mode part:

The two modes are:

- Contours
- Contour Areas

The Contour settings part:

Contouring methods:
- Increment
- Values
- AML contours

Specify values according to the chosen method.

The Charts part:

Select which charts to export data from.

The Export Format part:

Select which formats to export to.

Contour mode has the formats: VTK, Shape, ASCII Column, VTK ASCII, Dxf ASCII
Contour Area mode has the formats: VTK, Shape, ASCII Column, VTK ASCII, Dxf ASCII, S-57

The Output File part:

Select where to do the export. The selected location is common for all export.

Filename: Shows the name which will be generated for the files.
If file already exists: The default method is to overwrite any existing files, but it is also possible to make a copy. 

Make Boundary Polygon

This command will create boundary polygons (outline) from either points of surfaces in the selected chart(s). The command has two options, to make from Soundings or Seafloor data objects in the charts.

The Make Boundary Polygon Menu

The content of the menu

The upper part of the menu contains the project name and the name of the active folder of type Charts.

The Make boundary polygon part:

Options:
- Soundings
- Seafloor

Select to create the boundary from either Soundings or Seafloor:

Soundings: Create boundary polygon from the points data. The points will be snapped into a grid before creating the boundary.
Seafloor: Create boundary polygon from the Seafloor surface.

The Increments part:

Use Automatic increments: Calculate the increments from the bounding box for the points.

XInc (m): Manually specify increment in X direction.
YInc (m): Manually specify increment in Y direction.
Use YInc=XInc: Use the same increment in Y as in X direction.

The Chart Name part:
Select from the list which charts to apply.

The output file with the generated boundary polygon will ba saved under each chart with the name Boundary. This this polygon can be used by some gridding algorithms, and also exported by the Export Chart Data command.

Make Profile

This command will extract continuous profile data based on a line crossing the selected chart(s). The command has two options, make one Along profile or multiple Across profiles. The profiles will be seamless over the edges of the input charts.

The Make Profile Menu

The content of the menu

The Profile Data part:

Select XY profile dataset in the profile data folder. The output from the command will be saved in the same folder.

The Mode part:

Options:
- Along profile
- Across profile

Select to extract one along profile or several across profiles.

The Along Profile parameters part:

Specify the point spacing in the profile and optionally a start value (Kp) for the profile.

Point spacing (m): Specify the distance between the points in the profile. A value of zero will use a default spacing.
Start value (m): Specify a start value (Kp) for the profile. The value will be added to the profile length values.

The Across Profile parameters part:

Specify along spacing, profile length and spacing for the across profiles, and optionally a start distance for the profile.

Profile spacing (m): Specify distance between across profiles along the specified profile. A value of zero will use a default spacing.
Profile length (m): Specify the length of each across profile. The across profiles will be half this length on each side of the specified profile.
Point spacing (m): Specify the distance between the points in the across profiles. The across profile will get one point per specified value.
Start value (m): Specify a start value for the profile that will be used to calculate the positions of the across profiles.

The Chart Name part:
Select from the list which charts to apply.

The output file with the generated profile contain the length along the profile in a column named Distance. This is the distance along the profile added with the start value. The column KP is the distance in kilometers.
Across profiles will get a column named AcrossDistance with values from -width to +width. Negative values are on the left hand side of the profile line.
A start value of the profile length can optionally be added to the profile length.
Along profiles will also get a column named PointType. The values here will be Vertex or Interpolated. Vertex points are the original points from the input profile, while interpolated are created when executing the command.

The generated profile data is saved in the project into the same folder as the input profile. Along profiles will get the extension _alongProfile and across profiles will getb the extension _acrossProfiles.

Merge Surfaces

The purpose of this command is to merge selected surfaces into one surface.

The Merge Surfaces Menu

Select the surfaces to be merged by transfering the chart names into Selected Chart Name.

Default name for the chart containing the merged surfaces is mergedChart.
That name will be used if the field for the new chart name is blank.

A new chart name can be entered that will be used to save the merged surface in the same chart folder.
In either case the size of the merge surfaces will be the min and max values for the set of input surfaces.

If the task is to merge surfaces within a new chart frame, create first that chart and browse it in.
The algorithm will then use the definition of the browsed chart as the grid frame for the merged surfaces.

Priority when overlapping surfaces: The sequence of the selected surfaces determines the priority.

The grid increment for the merged surface can be selected from the first grid or specified explicitely.
The x and y grid increment will be equal. 

Points Classification

The Points Classification Menu

This command will generate classificated points for the selected chart(s).
Input to the classification algorithms are the grids called Seafloor that are located
under each "chart name" folder.

Theese are the classification options:
Shoals Deeps Ridges Saddles Valleys

Set the correct parameters for the selected options and click Execute.
The result is a set of points that tells where the selected classification points are located.

The classification points are saved under the <chart name> folder and a <classification>
folder with the name of the option and the parameters selected.

Shoals

Will find those grids nodes that are the shallowest within the Minimum distance.
The option Filter width is a mask moving over the grid and checking the centre node with the nodes around.
A shoal is detected when the centre node is shallower than the rest of the nodes in the mask. After the detection the points are sorted on increasing depth values, and by starting with the first (and shallowest) point, all points with a distance smaller than the Minimum distance will be removed. Then the same test is performed for the next valid point, etc.
The shoals are saved in <chart name> classification shoals_<filter width>_<distance>.

Deeps

Will find those grids nodes that are the highest within the Minimum distance.
The option Filter width is a mask moving over the grid and checking the centre node with the nodes around.
A deep is detected when the centre node is deeper than the rest of the nodes in the mask. After the detection the points are sorted on decreasing depth values, and by starting with the first (and deepest) point, all points with a distance smaller than the Minimum distance will be removed. Then the same test is performed for the next valid point, etc.
The deeps are saved in <chart name> classification deeps_<filter width>_<distance>.

Ridges

Will find those grids nodes that define a ridge. The two parameters are the
maximum ridge angle towards the shallow area and the minimum ridge angle towards the deep area.

Saved in <chart name> classification ridges_<maxshallowangle>_<mindeepangle>.

To see all ridge points set maximum ridge angle towards the shallow area = 90, and
minimum ridge angle towards the deep area = 0. Default setting is 20 and 5.
Test and tune the parameters to get the proper ridge points.

Saddles

Will find those grids nodes that have two low and two high neighbour points.
If the search radius is greater than zero, the lowest saddle point within the search radius
will be selected.

Saved in <chart name> classification saddles_<searchradius>.

Valleys

Will find those grids nodes that define a valley (which is the opposite of a ridge).
The two parameters are the
maximum valley angle towards the deep area and the minimum valley angle towards the shallow area.

Saved in <chart name> classification valleys_<maxdeepangle>_<minshallowangle>.

To see all valley points set minimum valley angle towards the deep area = 0, and
maximum valley angle towards the shallow area = 90. Default setting is 5 and 20.
Test and tune the parameters to get the proper valley points.

Find corresponding points in Soundings
This option enables a search in the Soundings dataset for the nearest point that was found in the Seafloor grid. The corresponding points are saved in <chart name> classification <type>in_soundings<parameter>. 

Remove Chart data

This command is executed from a folder with schema type Charts and will operate on data in the chart folders (with schema type Chart).
The command can remove data of different type, like Frame, Soundings and Seafloor specified in the menu. The command can also remove entire chart folders.

The Remove Chart Data Menu

The content of the menu

The upper part of the menu contains the project name and the name of the active folder of type Charts.

The Mode part:

This is the specification of the method for removing project data:

• Remove entire chart folder and data means that the selected chart(s) should be completely removed from the project. All data items and the chart folder itself will be removed.
• Remove specified chart folder item(s) means that the selected item(s) should be removed from the selected chart(s). Only the data items will be removed. If a data item does not exist for a chart, a log message will be written.
• Remove empty chart means that all the empty chart(s) of the selected chart(s) should be completely removed from the project. The check if the charts is empty can be if it has either a Soundings item or Seafloor. 

The Remove Data Items part:

Boundary: Use this button to remove the Boundary polygon for the selected chart(s).

Seafloor: Use this button to remove the Seafloor DTM for the selected chart(s).

Soundings: Use this button to remove the Soundings dataset for the selected chart(s).

Soundings_Accepted: Use this button to remove the Soundings_Accepted dataset for the selected chart(s).

Soundings_Rejected: Use this button to remove the Soundings_Rejected dataset for the selected chart(s).

The Required Data Items part:

Soundings: Use this button to define that the Soundings dataset is required for a chart.

Seafloor: Use this button to define that the Seafloor dataset is required for a chart.

The Charts part:

Select which charts to remove or remove data from.