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GeoPosition: Users Guide  | Handy Tips  Further Information  |  iTunes

GeoPosition Handy Tips

  1. 1.Determine a position on a map

First you look for the information about the scale, projection and datum of the map. In this case we have a map with a scale of 1:50.000, the projection UTM and the datum WGS84. Following the projection the UTM Zone (32U) is specified, which is required for the calculation of geographic coordinates from map projection coordinates. The scale of 1:50.000 means, that one millimetre on the map means 50 meters in reality.

On the image beside one can see, that GeoPosition receives the geographic coordinate 48:21:03.841 north / 10:49:09.969 east as current position. To determine this position on the map, select UTM/UPS as projection and WGS84 as map datum as specified on the map. GeoPosition calculates now an easting of 634,795.737 m and a northing of 5,356,920.56 m. The zone is calculated as 32U and so conforms with the zone of the map.

To determine the position in eastern direction you first look for the next vertical grid line, which is smaller than the easting value, in this case the line denoted with 634. The distance of the grid lines of this map is 2 km and the lines are denoted in kilometres. The distance between the grid line and the easting amounts now to about 800 m. Since 1 mm on the map equates to 50 m in reality, the distance from the grid line on the map is 800 / 50 = 16 mm.

To determine the position in northern direction you look for the next grid line, which is smaller than the northing, in this case the line denoted with 5,356. This is the distance from the equator in kilometres. The distance from the northing value to the grid line amounts to about 900 m, which equates 18 mm on the map.

To determine finally the position on the map you measure now 16 mm from the 634 km grid line to the right and 18 mm from the 5,356 km grid line up as illustrated on the following picture:

  1. 2.Calculate a geographic coordinate from a map projection coordinate

To send a meeting point to friends, you may use GeoPosition to calculate a geographic coordinate from a position on the map and to send it via E-Mail or SMS. For this purpose you first measure the easting and northing of the coordinate on the map, in the following example a point 13 mm to the right of the 642 km grid line and 19 mm above the 5,386 km grid line.

So the easting is calculated as follows: 642,000 + 13 x 50 = 642,650 and the northing amounts to: 5,386,000 + 19 x 50 = 5,386,950.

Enter these values as map projection coordinate in GeoPosition, select the projection (UTM/UPS), the datum (WGS84) and in this case the correct UTM zone (32U) of the map.

GeoPosition calculates so the geographic coordinate as 48:37:09,645 north / 10:56:08,307 east.

To verify the coordinate you may show the coordinate in the map view and afterwards you may send the coordinate via E-Mail or SMS:

  1. 3.Distance Calculation from the Current Position to the Entered Coordinate

To calculate the linear distance from the current position to a coordinate, enter the coordinate and switch distance calculation on. The distance is shown and below the geographic coordinate of the current position and the horzontal accurracy. In the map view a line is drawn between the current position and the coordinate and beside the line the distance is displayed: