European Plate Georeferencing

Some of the plates have georeference information provided by the server. Plates that do not have server georeferencing can be manually georeferenced. You can download manual georeferences contributed by other users and you may contribute georeference information that you create.

Plate Georeference Status

• manually georeferenced plates saved locally
• manually georeferenced plates contributed
• plates automatically georeferenced by server

There are two types of manual georeferencing:

• Four Point: This method can be used when the lat/lon lines on the plate to be georeferenced are vertical and horizontal, ie, no noticeable rotation or pinching is present. Two of the points must define latitudes and the other two must define longitudes.
  • Place the two latitude points anywhere with the greatest separation of latitude values. Likewise with longitude points.
• Eight Point: This method must be used when the Four Point method can not, ie, there is some rotation and/or pinching. Four of the points must define latitudes and the other four must define longitudes.
  • Place two points close to each of the four edges of the plate. The points along any one edge should be separated as much as possible.

Entering a Point

1. Open the georeference editing buttons by clicking the triangle button near the bottom of the screen. A red triangle indicates that some more points are needed for georef to be valid. Green means there are enough points to georef the plate. Gray means there is server-provided georeferencing for the plate, but you can override it by entering manual georefencing information.
2. Click the arrow buttons to move the magenta cursor lines to the georeference point to be entered. Long hold press for large jumps; quick taps for small steps.
   
3. Use the deg min sec buttons to enter either a latitude or longitude for the given point. Use FreeForm to enter minute or second values with the keyboard.
4. Click SAVE to write the point to flash storage. A triangle will be placed at the saved point with the saved numeric value. If no triangle appears, make sure that degrees, minutes and seconds have been entered.
5. Repeat until all 4 or 8 points have been entered. The triangles will turn green when a valid mapping has been entered. You may get 4 green on the way to entering 8 points, but the mapping with the 4 is probably not correct and you should proceed to enter a total of 8.

Deleting a Point

1. Use arrow buttons to move cursor somewhere on the triangle of the point to be deleted. The triangle should turn yellow.
2. Click the DELETE button.

Contributing a Georeference

Once you have completed a georeference and it shows the markers in green, you can contribute the mapping for others to use by clicking the CONTRIB button. Internet connectivity is required for this to work. If you do not have connectivity at the moment, you can contribute it later.

4 Point Example

This example only needs 4 points because the latitude and longitude lines are horizontal and vertical within a couple pixels. It's easy to tell that they are vertical and horizontal by placing the magenta cursor lines over the latitude and longitude lines.

There are 2 latitude markers along the left edge and 2 longitude markers along the bottom edge.

8 Point Example

This example requires 8 points because the latitude and longitude lines are not horizontal and vertical. There are 2 markers along each of the 4 edges. If only 4 points were given, the aircraft placement wouldn't be correct when a distance away from the 4 given points.

4 Point Aerodrome Example

This example of using 4 points uses 4 runway ends to give a good spread of latitude and longitude inputs. The east/west runway gives a good spread of longitude, and the north/south runway gives a good spread of latitude.

It is valid to use 4 points because the diagram is oriented East up, so the lines of latitude and longitude are vertical and horizontal. If the diagram were slightly rotated, eg, 100° up, 8 points would be needed.