How to convert / reproject MGI map to WGS84?

Hi everyone. Thx for letting me in.

I have some image map, which I have converted into a real map using a tool (OkMap) (Later on,Im using orux to convert into orux map for mobile phone) My map is MGI Balkzan Zone 7, and when I simply get coordinates from it and put in google maps, they are not showing the same position.
So, I want to convert that map into WGS84.

It is my first time working with maps, so sorry for potentially using wrong names. I guess this is calling - to reproject a map.
If anyone could help me, thank you

Answers

  • sphillipssphillips Posts: 174
    Assuming all your data is loaded with the correct coordinate system, you just need to switch your projection from MGI Balkzan Zone 7 to Geographic (Latitude/Longitude).

    1. Click on Configure (Spanner)
    2. Projection
    3. Choose Geographic (Latitude/Longitude) for the Projection
    4. Choose WGS84 for the Datum
    5. Choose ARC DEGREES for the Planar Units
    speccko
  • specckospeccko Posts: 9
    Thank you so much for answering and trying to help.
    Im sorry, as I said, im pretty new to this.

    I have loaded in GM a geoTiff file with MGI projection. Converted it as you said. But only what I saw is that the image is a bit stretched now.
    I exported again in GeoTiff format and now, when I from OKMap try to get coordinates still i have the same issue - on google maps, it shows the point like few meters on right side more that should (200-300m)
  • sphillipssphillips Posts: 174
    WGS84 data does look quite stretched so this is normal. Can you share your data?
  • specckospeccko Posts: 9
    What data exactly you mean?  :)
  • sphillipssphillips Posts: 174
    Geographic Coordinate Systems e.g. Geographic (Latitude/Longitude); can appear to look stretched/distorted when displayed in GIS software compared to Projected Coordinate Systems e.g. MGI 1901 Balkans Zone 7; which uses the Transverse Mercator Projection.

    The data I am referring to is your map. If you can share it (zip it up and attach) we can see what the problem is. If you can't that's fine. 

    As a quick check does loaded World Imagery line up with the map as expected when the map is loaded with the original coordinate system (MGI 1901 Balkans Zone 7)? If it doesn't then your coordinate system and or datum may be wrong to begin with.
  • specckospeccko Posts: 9
    Here are few screenshots from OK map with the right setup for the image I have. You will see that the gird fits in pixel (with any other projection, that is not the case) I looked for this like one week, since I didn't know how to read instructions under the map.
    In zip you will find tiff file, converted from GM and also, not converted version.
    As i said, I only want to be able to pick the point from map, and get exactly the same on google maps.

    Thank you a lot for helping.

    Link to download:

  • sphillipssphillips Posts: 174
    The link doesn't work for me sorry. It says '403 Forbidden'.
  • sphillipssphillips Posts: 174
    I think I understand the problem now. I have applied a Geographic (datum) Transformation to your map to correct
    it; specifically MGI_To_WGS_1984_4. See if this fixes your problem. By the way I used ArcGIS to fix this as I don't have Geographic Calculator.

    https://drive.google.com/file/d/1kMFWAFtDko7yDsFtAd1C4ppAmSSf8-gG/view?usp=sharing
  • specckospeccko Posts: 9
    Thank you, but unfortunately, it is still wrong, actually, I think there happened some mistake in conversion. 
    Look at the ScrSh. I tried manually to fix but no luck. You should get on gmaps a point somewhere in Serbia - Serbia / Romania border.

    Also, I marked on the map, left top corner the 22 degrees is missing, I added it in screenShot

    https://drive.google.com/file/d/14IMjJrbWmFDIl-Je7TFHgFW-wloeIoGr/view?usp=sharing
  • sphillipssphillips Posts: 174
    I'm not sure where you are getting these Lat/Long values but as far as I can see the map is correctly placed and the Lat/Longs are correct. Maybe this is an issue with orux maps rather Global Mapper?


  • specckospeccko Posts: 9
    But now, when I get this coordinates from the image you posted, look where Im located:


  • sphillipssphillips Posts: 174
    speccko said:
    But now, when I get this coordinates from the image you posted, look where Im located:


    I believe you are expecting the data to be located by the arrow rather than further north by the cross. I have checked the map against the aerial imagery and it looks to be lined up correctly.

    The island like feature might be tidal nut can just about be seen submerged in the Bing imagery. It is also visible on the Street Maps overlay. I’ll load post a screenshot when I am in work tomorrow.
  • sphillipssphillips Posts: 174
    This is comparison of the layers from the same view as promised. As you can see they are in the right location and your point should be correct. The island/sand bar is below the water in the aerial imagery.

    Mykle
  • specckospeccko Posts: 9
    Thx Phillip :)
    I have tomorrow to sit in the front of my pc and check this.
    But still, i thougt, i can get geo location from this map (converted image) and the same coordinates paste in google maps (on website - online) and get there the point from converted map.
  • specckospeccko Posts: 9
    Hi again.
    I played around and figure out, that works like this:
    44°25'43.3"N 22°28'33.6"E  OK MAP
    44°25'41.1"N 22°28'11.1"E  GOOGLE MAPS

    So I need to take from E(east) always 12" when i get coordinates from my map, to get some position in google maps.

    Not sure if there is no better way.

    I understand now FILIP, what you showed me, but still can get directly to GMAPS...
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