AlpineQuest & OfflineMaps

Excuse my poor google translate into English.

Here above is a proposal from a user of 4pda.ru Russain forum:

Sometimes I found coordinate shift in some online and offline (file based maps) created in other applications (MOBAC, SAS.Planet etc.). I think this error occurs while making coordinate calibration of a map (the value is rounded to N digits after the decimal point, the accuracy depends on the digits after the decimal point).
My example is shown in pictures. I was at this place by myself
1. the position of the GPS coordinates (actually screen center coordinates)
2. the position on the Russian old military map (g_RKKA map)
3. the position on the Hybrid Map.
The distance between 2 and 3 is ~ 80m. It is too much in some cases (limited visibility in the forest, in the mountains or in the open water.) It would be very desirable, if necessary, to be able to make adjustment (shift) of any map displayed on the screen.

I see it this way: To add an item “MAP CORRETION” to the menu of displayed maps
When activated and while being at the reference point (crossroads, the beginning of the ravine, crossing the river, etc.) to move the map to match the point with the center of the screen.
The application should calculate the coordinate difference between two points.
When finished and after receiving confirmation of the end of the action to apply the received correction either to the reference coordinates of the map, or to the GPS coordinates that stand for this map (I ask the respected Author to forgive my ignorance, but I do not know at what level the map interacts with the GPS receiver, I am not a programmer).
Also to add the item "RESET CORRECTION" in the map menu on the screen.
It would be nice to save or reset the correction when users exit the program – to add check-box "RESET CORRECTION ON EXIT" because AQ users may have different tasks either navigation in a limited area (mushroom pickers, fishers etc.), or navigation in different locations (tourists, off-road etc.)

P.S. I would Like to add that saved tracks and waypoints won’t be shifted because they use the true GPS coordinates. The shift is only for visualization. It will be very comfortable to use maps for small scales.

Additional

Hi Alex,
I understand what you mean.
However there is something you need to be careful: is the shift the same for all the map?
When you calibrate old maps, sometimes it's difficult to have an exact matching for all the map, maybe because the old map projection is not exactly known or because the map is not exactly on scale. So sometimes, for example, the calibration is correct in the middle, but it's shifted in one direction on the left side and in another direction on the right side... So a simple shift is ont sufficient and will only move the problem to somewhere else.
Anyway, as you asked I plan to add the ability to calibrate images from the application, so in case of errors I think it will be possible to make a new calibration of the map...

Thanks!!!!