Map registration issue

Alan can you give an example of a location or two where it happens, and do you have any other maps where it does or does not happen.

Oziexplorer maps are called raster maps. Ozi isn't aware of any features on the map like roads or railways. It just calculates your GPS derived position onto a calculated grid on the map and sticks you at that location. So it is strange that it relates to the proximity of railways.

This phenomenon is called feature displacement. Simply put, during the map production process, owing to the scale of the map there isn't enough room to show the railway line and the road in their true position due to the thickness of the lines and the symbols used for each feature, so one has to be displaced (off set). If this was not done the road would be on top of the railway line and this would be very messy looking and unclear to read. There is a priority for displacing features and in the case of railway lines and roads, the railway line has precedence so it is depicted as close to its true position as possible while the road is displaced.

Hypothetically, the cross tie on the railway symbol on the map might be perhaps 1 mm long. This equates to 200 metres on the ground if the map scale is 1:200,000. The road, depending on its classification might be from .50mm to 1.0 mm thick so again on the ground this measures between 100 and 200 metres wides. If in real life the railway and the road are separated by say 100 metres they would overlap.

The maps used in OziExplorer are image files, the data is not dynamic as say in a Tom Tom which uses vector data, so the features on the map are static. They don't move apart as you zoom in or close up as you zoom out. They do in vector data GPS such as TomTom and Garmin.

WBS

In my travels when we were going past Port Stephens the road showed as being about 100m to the right which would have put us driving down a salt flat. Was like that for quite a long way.

Was using a Tomtom Go730.


Dont know why it was like that when generally it was spot on.

Any ideas