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Once the project has been created, you will be prompted to calibrate the floor plan or site map. Calibration is the process by which you  “tell” the application about the map dimensions (and coordinates, if you perform a GPS survey). Depending on the survey mode selected on the tool bar, clicking the Calibrate button on the tool bar (the right button on the illustration) will allow you to perform either standard (non-GPS) calibration or GPS calibration. GPS calibration is performed if the GPS survey mode is selected (the “satellite” button on the illustration). In all other cases, standard calibration is performed.
Standard Calibration (non-GPS)
To calibrate the map in this mode, you need to know the distance between two points on the map. That can be the distance between two walls or windows. Click on the first point of the distance, and move the mouse pointer to the second point while holding down the left mouse button. Release the left mouse button when the mouse pointer is over the second point. A red line indicating the distance will be shown. At the bottom of the screen, enter the length of the red line and click Apply.
GPS Calibration
To prepare the map for a GPS survey, you need to add at least three reference points with known geographic coordinates. To create a new reference point, click Add new and drag the point marker to a location on the map whose coordinates you want to enter. After that, you can do one of the following:
| § | Enter the coordinates of that point if you know them, or |
| § | Walk or drive to that point and use your GPS receiver to get your current coordinates. |
If you use the first method, simply enter the latitude and longitude of the new point in the corresponding fields on the left in one of the standard coordinate formats—e.g., 50.435237, 50° 26' 6.85" N, or 50° 26.114' N. Be sure to double-check the numbers that you enter. Entering precise coordinates is extremely important for the accuracy of the subsequent data collection and analysis. If you use the second method, turn on your GPS receiver, connect it to your computer, and click Get from GPS Receiver. TamoGraph will then connect to the GPS receiver (or display a GPS configuration dialog, if you have not configured it) and read your current coordinates. Once the latitude and longitude have been entered, click Set to save the coordinates of the first point.
Repeat these steps for all points. The points should be as far apart as possible and not located on a straight line. You can enter more than three reference points, but this is usually not necessary if your site map has correct proportions. Click Apply when done.
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