How to produce a plot of cross-sectional data
  • 06 Oct 2022
  • 4 Minutes to read
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How to produce a plot of cross-sectional data

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The purpose of this function is to produce a plot of cross section data from a user specified location. The tool requires you to define a polyline on your map to represent the cross section location. The tool will then read the data from the loaded GIS datasets underlying the polyline. The polyline can be loaded as a separate shapefile layer or drawn in Flood Modeller as a new layer (using the shapefile editor tool). Alternatively you can utilise the Measuring Tool to draw a (temporary) polyline as your cross section.

Tell me more about the 2D Plot Section tool

The following data has to be loaded into the list of layers on Flood Modeller in order for the Cross Section Plot Tool to operate:

  1. A polyline shapefile which is either loaded as an external layer or drawn (with the shapefile editor) as a new layer. The tool expects only a single polyline in the specified file. However, in cases where there are several polyline features (representing cross sections) in the specified shapefile, then the cross section chart produced will show the information from all of these cross sections on the same chart. Alternatively the user can draw a 'temporary cross section' in the domain of the 1D or 2D model results using the Measuring Tool.

  2. A ground grid to extract the ground elevation information from;

  3. A TIN file with 1D results loaded or the 2D model results files to extract the water elevation information from (if necessary).

To start the process, click the Plot Section button in the 2D Results tool group. A new window will appear giving you the option to either select any polyline shape file currently loaded in your map or to draw a new line to define your cross section. To use an existing shape file select it from the displayed list and click OK to continue. To draw a new line click the Draw button. This will activate an instance of the measure tool and you can click anywhere on the map to start drawing a line to define your cross section. Each subsequent click will add a new point to the line. Double click to complete the line and stop drawing.

After the shapefile has been selected, a Cross Section Plot window will appear; on the left hand side you need to select the grid file, the TIN file or one or all of the components of the 2D model results file you would like to see shown on your cross section plot. After this information has been selected, you will be able to see the resulting cross section plot, as shown by the example below.

plotsectionloaded.jpg

The cross-section plot viewer is used to view cross-sections which have been loaded from a shape file. The cross-section is loaded with a default step of 20m. If you zoom in or out, the section step will change automatically.

The graph within the viewer can be manipulated in a number of ways. To zoom onto a specific area, the user should hold and drag the mouse over the relevant area. In order to pan, the user should hold and drag the middle mouse button. When the user right clicks on the cross section plot, a number of options will be made available:

Copy Image - Copies the image in the viewer to the clipboard.

Export to Excel - Exports the cross-section data, and water elevation data if present, to Excel.

Change Point Spacing - Changes the spacing of the chainage points on the cross section for which the information from the underlying grid or results file is extracted. In the next window the user needs to specify the value of the interval between these points in metres, i.e. the smaller the number entered, the more chainage points will be used for the interrogation of the underlying data.

Change Line Colour - Changes the colour of the cross section line

Save Image As - Saves the image as an .emf, .png, .gif, .jpeg, .tif or .bmp file and specifies the location the image should be saved to.

Show Symbols - Adds a pattern to the cross section line for easier identification

Page Setup - Gives access to the page setup window, allowing the user to edit how the page is setup for printing.

Print - Opens a window allowing the user to start printing as well as to select a printer and set various other related settings.

Show Point Values - When 'Show Point Values' is activated, holding the cursor above the cross section line will provide information about the X, Y and Z co-ordinates of the nearest point on the status bar below the graph.

Un-zoom - Un-zooms to the previous zoom extent.

Undo All Zoom/Pan - Cancels all zooming and panning which has been carried out, returning chart to the original view.

Set Scale to Default - Sets the scale of zoom level to the default one (the one used at the start of using the cross section tool).

There are the following buttons available on the cross-section plot form:

Clear All - Clears the Cross-section graph of all data.

Refresh - Updates the view of cross-section


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