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rhumbaflappy

Coordinates question (IMP!)

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Dear all,Hope someone can shine some light on this....It could be a simple question but I'm not quite sure of the answer...given the lon/lat coordinates of a city, where exactly is the point in the city having such coordinates located???Is it approximately the center of the city?I'd be grateful for a reply peeps,Cheers all,Storm

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Hi Storm...glad you posted here. Saw you post at Netwings but the best place is here for your questions.I would imagine that the coordinates of a city are taken from the approximate center. However why don't you let us in on what you arte trying to do? Maybe then we could get a better understanding of what you need.Thx!

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Cheers Thx for replying :-beerchug..Anyways, I'm redesigning some coastlines in Coastline Maker. I have some good maps to draw the contour lines. I want to be sure where city coordinates actually lie so that I can accurately position the maps on the default scenery of FS2002 within coastline maker. Hope I've explained myself well enough :)Cheerios,Storm

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Hi Storm, I've done a fair bit of work with Coastlinemaker and I think you will have to compromise a bit to fit your updated coastline in with the default coastline. I have used maps for reference but have not overlaid them on the top down screen shots I use in Coastlinemaker. The default coastline is too far out of true and you would have to use trial and error to try to get the maps to the same scale as your screenshot. I tried doing this but gave up in the end. There are too many variables. If you have an airport in your scenery, the FS2002 runways are usually placed fairly accurately and I would use them as reference points and then pick a few prominent landmarks, (e.g. the points of peninsulars. centre of islands)get the lat. long. of these by slewing around in the sim then compare these to the actual map and from there use a bit of artistic licence to put in your coastline. you will also have to match the ends of your coastline to the existing coastline. Tony

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Depending on where you got your information from the coordinates could be just an approximation of lat and long for the city, so it could be anywhere. If you are just trying to find out where the city is in relation to the world that is OK, but it is much too general for setting up a starting point for an accurate coastline. To do that sort of thing I think street intersections and other easy to recognise features are really good for pinpointing coordinates.Ground2K is good for georeferencing a background image, maybe try that? And remember that the lat and long from your map should be referenced to the WGS84 or GRS80 ellipsoid. Otherwise your map coordinates will not relate to the FS World as well as you may like.Derek

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Hi all.A good source for city maps is MapPoint.comZoom in to get just enough street resolution, then right click on the map to download a GIF ( easily translated to BMP in a paint program ). Choosing the e-mail option from MapPoint yields a line like this:http://maps.msn.com/map.aspx?ID=27CiJ.&C=5...sels%2c+BelgiumC=50.84841,4.34968 is your centerpoint in lat,long in decimal degrees.S=800,740 is your span in pixels x,yA=25 is the code for resolution... this is a span per pixel in meters ( 13.5m in this case ) A50 is 27m. A150 is 81m. Trust me on this. ;)As Derek pointed out in the above post, the projection is wrong. It's orthographic ( distance in meters ), not geographic ( distance in degrees ). But for a single unmerged map of A=25, the distortion is very slight at the edges... so it should still be OK for Ground2k. The maps are perfect for Airport ar FSSC... with the meter/pixel as 13.5 ( or the pixels/100 meters as 7.4074, for Airport ). Unfortunately, FSSC uses an antialiasing formula for zooming, that renders many backgrounds unusable.... but they could be enlarged before use in FSSC, as long as you also altered the meter/pixel ratio.For Ground2K, you'll need to derive a NW and SE point of known lat-long, in order to georegister the BMP. ( Just click on the MapPoint image to a road intersection near the 2 corners, and click on the e-mail option to get those points ).Dick

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