Julian Foad writes: > > Norman Vine wrote: > > > > vmap0 can be off by ~500 meters and still be considered > > accurate since it is 1:1,000,000 > > Every time I see a map scale ratio like "1:1000000" for digital mapping data, I am > confused. For a paper map it means "1 > length unit on the map represents 1000000 length units in real life", but a line > segment in digital data has no fixed > length: it can be drawn to any arbitrary scale by the display software. > > I assume there is a convention about what a scale ratio means in digital mapping. > Please can someone enlighten me? Then > I might be able to understand the first part of that statement (about the accuracy).
You are right scale doesn't mean as much in the digital world but... there is still a strong correlation betwen map scale and appropriate use < in a navigation sense > So say your monitor is approximately 1/3 of a meter wide then the appropriate zoom for DCW data is when your have approximately 300 kilometers in view on the screen. < 1,000,000 * 1/3 = ~300,000 meters > i.e. this is the scale < zoom > that this data was made to be 'accurate' at Obviously FGFS is using this data is extreme 'overzoom' googling on overzoom should lots of related hits HTH Norman _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
