Verification of the accuracy of measurements

The satelite maps are interactive and their possibility to identify coordinates in any point of satellite image gives the possibility to measure length and distance between the objects, to calculate area of buildings and relief forms on earth, radius and area of circle, distance along the road, to measure angles and to define azimuth position.

Let's carry out several experiments to test the accuracy of the program for areas measurement work. First of all, let's try to make the sample calculation of Australia area. Just in five minutes we create polygon, enveloping the continent and consisting of 258 dots. The task becomes easier due to the fact that all the markers may be dragged and placed in another place. And this is what we get.

The continent area, calculated with the help of program, is equal to 7687244.54 square kilometres (2968061.71 square miles). To check our measurements, let's address Wikipedia; it states that "Australia's landmass of 7,617,930 square kilometres (2,941,300 sq mi)". It means that our measurement almost match real values.

Polygon, enveloping Australia, for the continent area measurement

Westminster Bridge width measurement

Let's carry out another experiment to define the width of Westminster Bridge over the River Thames (London). We know in advance that its width is 26 meters. To do this, we will use another tool to measure lengths, perimeters, and distances on the map.

Amazing, but the calculated by the program width is 26.05 meters. It means that with the help of maps you may make rather accurate measurement. However, if you need to measure, for example, the area of beach or ravine, or the distance between islands, it is always required to consider the fact that satellite maps are upgraded not very often and natural relief may change from time to time.

Self-checking the accuracy of measurements

Let's consider another way to check the accuracy of measurements, where you will gain personal experience in geodesy. Let's measure the area of your house, or the lawn in front of the house. To simplify the calculations, we will use a rectangular object.

To do this, open the online map area calculator application and click New Calculation. Then, go outside and physically measure the lawn's length and width in feet (meters), and multiply the results. The result will be its area in square feet (square meters), since the area formula for a rectangle is length multiplied by width.

Now, for verification, use your smartphone's GPS module to find the coordinates of the vertices of this rectangle (the lawn) and sequentially input these coordinates into the map area calculator, then compare the results.

If your experiment is successful, you can proceed to measure something significantly larger, such as a golf course, which does not necessarily have to be rectangular.