1. Centre at (287914, 740615) and choose a display scale of 1:500.
2. Select the menu item, turn on the
snapping to a feature switch, and click on to exit.
(287914, 740615), 1:500
3. Select the menu item, turn on the
User Defined Polygon switch, and click on to exit.
The switch allows you to define a polygon anywhere on the display
window and have its area calculated. Since we have the snapping to a
feature option turned on, we will be using the existing corners of the
house and hence will compute the plan area of the house.
4. Point at the four corners of the house in either a clockwise or
a counterclockwise order. Then click on the right mouse button to
terminate.
The GIS knows that you are measuring an area, and therefore will
close off the outline of the house automatically. You could enter the
fifth point if you wish, and click on the right mouse button to finish.
5. Area measurement, like distance measurement, is performed on
both the flat map surface and on the curved ellipsoidal earth. The
slight difference of 0.125 square metres in this example is the result
of area distortion introduced by the map projection used.