In this example, a map page from the 'Sydway' street directory is used as a background map for digitising vector data or object positions. The map uses the AMG84 grid (ellipsoid ANS).
The digitiser can either be the mouse cursor in conjunction with a background map (used in this example) or a graphics tablet (see entry 'Drawing Slate' which was from a Calcomp digitzer that was connected to the computer).
Here we select AMG84 with the ANS ellipsoid and UTM zone 56 as the map is in that zone.
At that stage, only the leftmost method was implemented using a known point, the scale and the map rotation.
Here we enter the false northing and false easting of the lower left corner of 6250000 metres North and 332000 metres East and then click on the corresponding point on the map. The dialog window is non-modal and can be clicked away. It reappears when the mouse is clicked into the map (main window).
Scanned maps are not usually perfectly aligned. Therefore, if they have any rotational error, this needs to be known and determined. The user clicks on two points along a horizontal line on the map. (The dialog can be clicked away again).
The program needs to know how to convert the device (background map pixel coordinates or digitiser coordinates) to actual distances on the map. The user clicks on two points where the distance is known for. Here we used 8 squares which corresponds to 2km (250m each square).
This step is optional. It is needed if a printed map is distorted, i.e. the scale in X-direction is not exactly the same as in Y-direction. This Sydway map page suffers from that problem.
At this stage the user can try out the conversion. The dialog can, as before, be clicked away if needed. The user can go back and make changes if required or complete the calibration.
In this screen shot the mouse pointer was almost exactly over the intersection of 6250000mN/332000mE in Zone 56. The program shows, in its status bar, the latitude and longitude plus some other values in MS Flight Simulator's geographical hierarchy.