Unclos Tutorial G. Generation of distance lines and mid-lines

• Display the baseline you imported or generated in one of the two previous exercises.
• Make sure the baseline has the “Base Lines” schema in the project window. (If it uses a different schema, right click the dataset and select “Set Schema”->”Base Line”.)
• Right-click the baseline and select the command object “generate 200M Line.”
• The new line should now be available under “1. Maritime Lines/200M Lines.”
• Display the 200M line.

When you have made changes to the project it is always a good idea to store your changes. Click the save button: in the project tool bar in order to save your project.

• Right click the base line dataset, and select "Edit Schema Commands". The Base line schema command list will appear.
• Double click the "Generate 200M Line" command object in the command list, and the command editor will appear.
• Type in the new point spacing 1 and change the unit to Nautical miles.
• click OK in the command editor, and the schema command list.

You have now set the "Generate 200M Line" to use 1M point spacing on the distance line. Repeat the first exercise in this tutorial in order to generate the line. Note that if you reduce the point spacing, the algorithm needs more time to do the calculation.

• Right click the baseline dataset, and select "Edit Schema Commands." The Base line schema command list will appear.
• Double click the "Generate 200M Line" command object in the command list, and the command editor will appear.
• Change the Execution Mode to "Interactive" and click OK. You have now set the "Generate 200M Line" Command to be interactive and the panel will pop up every time you click this command.

Setting the Schema Command to "Interactive"
• Right click the baseline dataset again and choose "Generate 200M Line..." (the three dots indicate this Schema Command is set to interactive mode).
• Check the box next to "Generate base point connection polygon"
• Click Execute and Display the new dataset found in the 200M lines folder. Also display the points by right clicking and choosing "Display Points."
• Re-name the dataset to something more meaningful like, 200M critical points"

200M line with critical points on baseline in blue

Notice not all points on the baseline are included as "critical points" used to generate the 200M line. This is helpful in determining and visualizing which points on the baseline contribute to the limit lines, whether the user generates 200M, 24M, 12M or any other distance calculation with this option.

• Additionally, open the table view for this dataset and notice the column for "Base Line Index". This shows which point on the baseline contributes to each point on the 200M line.
• Toggle the display between polygon mode and wire mode with the "w" and "s" keys.

• Open the tool from Tools > Distance Calculations
• Select an appropriate datum and coordinate system.
• For distance calculation method, select "ellipse approximation". "Flat earth" calculates in the metric values of the projections.
• Make sure that the graphic window is in 2D
• Click in the graphics window to measure distance to previous position. The panel also shows coordinates of the cursor position.

• Right-click on the dataset > Edit points and lines ...
• Click on the "Delete" pane, then on the "By closed line" pane.
• You may want to redisplay your data using the "Display"-button in the lower part of the panel.
• Click the "Start"-button and start digitizing, encircling the parts of the lines that should be removed.
• When encircling is almost complete, click the "Connect to start and End" button. Then press "Delete points INSIDE" to remove the encircled points. (Alternatively use OUTSIDE).
• The edited dataset is not written back into the project until "Execute" is clicked. Observe the options for "Save as an extra copy", "Overwrite input dataset" etc.

• The coastline of Starfish Isl. is found in the Coastline folder.
• You may either use the coastline as a baseline - or create a new baseline.

The coast lines of Starfish Islands and Atlantis.

The mid line will be generated in the "Active window". This window is set when you use "Scale window to data" or "Scale window to folder".

• Right click the folder containing the base lines and select "Scale window to folder"
• On a dataset of schema "Baseline" you can right-click and "Generate mid-line ...". In a popup menu you are then asked about what to generate mid-lines against. Select the other baselines and click ok.
• The result mid line will be generated in a new folder called "1. Maritime Lines / Mid lines"