Measuring the Area within a Polygon

RockPlot2D | Measure | Area

Use the Area menu command or toolbar button to measure the area within a single convex polygon on an image displayed in a RockPlot2D window. The computed areas are displayed in the window's data pane.

Step-by-Step Summary

1. If necessary, open the diagram for which you wish to compute area (see Opening Plot Files) or click in the current RockPlot2D window containing the diagram.
   ! The image can be in any coordinate system (mapping units, diagram units); the area will be recorded in those units squared. It’s important however that the image be created at equal units along the X and Y axes for the area measurements to be accurate. The image does not, however, need to be displayed in RockPlot2D at equal scales (vertical exaggeration can be < or > 1).
   
2. Select the Measure | Area menu item, or click on the Measure | Area button at the top of the screen .
   The Area button is available in the Measure drop-down menu.

   

   The program will be in "Measure Area" mode, as noted at the bottom of the screen.

3. Click on the starting point of the polygon. The program will display a triangle-shaped symbol to mark the start of the polygon.
   
4. Continue digitizing points on the screen display along the boundary of the polygon.
   
5. To close the polygon, double-click on the second-to-last vertex.
   
6. The program will close the polygon on the screen display, and compute the area contained within it. The area will be displayed in the data window to the right. It will await another polygon.
   
7. Repeat this process if you wish to digitize another polygon for area computation.
   
8. To terminate the Measure Area mode, click the Measure Area X button at the bottom of the window, or click the arrow button at the top of the window, or press the Shift+Escape keys.

! If you recreate or close the RockPlot2D window before copying the data to the clipboard, it will be lost. The data is not stored in the Rw2D file.

Tips

• Use the Options | Export | Windows Clipboard menu option (above the data pane) to copy the contents of the data window to your computer's Clipboard, for pasting into any document. See The RockPlot2D Data Window.
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See also

• Digitizing and Measurement Options

Related tools

• Drawing Polygons for inserting a polygon into the map or diagram.
• Measuring Perimeters for measuring the perimeter of a polygon.
• Digitizing Polygons to capture the vertex coordinates.
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