After another long absence (internet problems) I have returned to working on the Flanders Roads project. While I was gone, the proverbial penny dropped for me on how to use GoogleEarth directly with G2k with greater precision without resorting to a lengthier method involving FSSC. But in the meantime I have apparently forgotten how to use MkAFD. :help:
I have followed two sets of instructions and several approaches of my own, but I end up with bgls and airfield data that plonk me hundreds of miles from my intended airfield destination.
Could someone prod my confused grey cells? I recall there was a certain trick about entering the co-ordinates...or did I dream that bit?
Thanks and cheers, Grinseed
Well, my version of Google Earth displays coordinates in decimal degrees - that is, degrees to the left of the "." and decimal parts of a degree to the right of the "."
So, for example, N50.50* in Google Earth degrees is the same as N50 degrees, 30 minutes, 0 seconds in conventional degrees, minutes, and seconds format. If you were to interpret the .50 (Google) as minutes, you'd be 20 minutes off. But that wouldn't account for hundreds of miles.
Conversion from decimal degrees to degrees, minutes, and seconds goes like this. Say you want to convert 50.93 degrees to degrees, minutes, and seconds:
multiply the decimal part of the degrees (0.93) X 60. This gives you your decimal minutes = 55.8
Now multiply the decimal part of the minutes (0.8) X 60. This gives you your decimal seconds = 48
The decimal seconds just happened to come out a whole number in this example.
Now combine the degrees, integer part of the minutes, and seconds like so: 50* 55' 48" - that's 50 degrees, 55 minutes, 48 seconds in plain english.
However the "airbases.dat" file uses degrees and decimal minutes format. So forget the seconds and go with 50* 55.8' - that's 50 degrees, 55.8 minutes in plain english.
You can tell what format is being used by paying attention to the symbols. For example, N50.93* means 50.93 decimal degrees in plain english. When you see a "." symbol anywhere, it means that number is a decimal number. So 55.8' means 55.8 decimal minutes in plain english. If a number is decimal, there shouldn't be anything to the right of it. That's included in the decimal part.
And, just so there's no misunderstanding, 55.8' does
not mean 55 minutes and 8 seconds. It means "55 point 8 minutes". Big difference. "point 8 minutes" is 48 seconds.
Also, there is an offset between Google coordinates and CFS2 coordinates even after you get them into the same format. The offset varies in different parts of the globe. You just have to figure out what the offset is in the area where you're working. It's not a huge offset. Maybe a mile or so in some areas, but it's noticeable.