Mapping Your Landings - By Whiterafter

[whiterafter]

Some of you (including me) might be interested in charting your path across the Kerbol system, maybe where your rovers are going or where your fearless Kerbals planted their flags. The coordinate system offered by KSP seems really nice, but it isn't completely accurate and is flawed. Here's how you do it.

There are 2 websites I will use today, KerbalMaps, and a FCC calculator.

First, get your coordinates from KSP.

According to KSP, my impact probe on Laythe splashed down at

75-56-56 North

259-23-56 East

Second, check to see if any of the first numbers are above 180. If so, KSP has compiled them incorrectly, but there is an easy fix to this. Subtract 180 from that number (For me that would be 259). Then subtract THAT from 180 and reverse the direction. You can leave the next 2 numbers untouched.

259 EAST - 180 = 79

180 - 79 = 101 WEST

Third, using this website (the first and uppermost calculator) insert the numbers, including any fixed numbers if step #2 applied to you.

Fourth, if your first coordinate is in the South, put a negative sign in front of it. If your second coordinate is in the West, put a negative sign in front of it.

Fifth, fill in this URL to upload the location of your site to KerbalMaps. Of course, delete the [] around the numbers and planetary body.

http://www.kerbalmaps.com/?body=[PlanetaryBody]&loc=[Coordinate1],[Coordinate2]

Enjoy your map!

[Pecan]

Got to love navigation :-)

[Reactordrone]

+360° E notation is correct for non Earth(Kerbin) bodies.

[whiterafter]

+360° E notation is correct for non Earth(Kerbin) bodies.

It's necessary for the FCC translation however

[Heimdall5008]

Second, check to see if any of the first numbers are above 180. If so, KSP has compiled them incorrectly, but there is an easy fix to this. Subtract 180 from that number (For me that would be 259). Then subtract THAT from 180 and reverse the direction. You can leave the next 2 numbers untouched.

259 EAST - 180 = 79

180 - 79 = 101 WEST

If you want to have it a bit easier, you can just subtract your value from 360

360 - 259E = 101W

And for the North/South coordinate (latitude) I assume that the values are between -90 (south) and 90 (north). So therefore for your latitude you have to correct your values if they are above 90. Then the formula will be, e.g.:

180 - 91N = 89S

Edited January 4, 2015 by Heimdall5008

[DeMatt]

The coordinate system offered by KSP seems really nice, but it isn't completely accurate and is flawed.

...so what exactly isn't accurate and/or is flawed? I did a little testing and the only bug I found was that <1° latitudes registered as "North", regardless of whether they were actually north or south of the equator.

There are 2 websites I will use today, KerbalMaps, and a FCC calculator.

You don't need the FCC calculator, just an understanding of how to convert from "degrees-arcminutes-arcseconds" to "degrees-decimals". Specifically:

1. Read the DDD°MM'SS" number and split it into its three components.
   
2. Divide the SS" number by 60 and add it to the MM' number.
   
3. Divide the new MM.mmmmm' number by 60 and add it to the DDD° number.
   
4. You now have a DDD.ddddd° number.

Second, check to see if any of the first numbers are above 180. If so, KSP has compiled them incorrectly, but there is an easy fix to this. Subtract 180 from that number (For me that would be 259). Then subtract THAT from 180 and reverse the direction.

As Heimdall5008 notes, you can just subtract the 360>longitude>180 number from 360, instead of this two-step calculation. If for some reason the longitude is greater than 360°, then you can subtract 360 degrees instead.

You can leave the next 2 numbers untouched.

This is wrong. To put it in perspective:

270 degrees 20 arcminutes East is 20 arcminutes eastwards from 270 degrees East, 40 arcminutes westwards from 271 degrees East, and 40 arcminutes westwards from 89 degrees West. By your formula, we convert the displayed 270°20'0"E to 90°20'0"W, instead of the 89°40'0"W it actually is - a difference, on Kerbin, of almost 14 kilometres.

And for the North/South coordinate (latitude) I assume that the values are between -90 (south) and 90 (north). So therefore for your latitude you have to correct your values if they are above 90. Then the formula will be, e.g.:

180 - 91N = 89S

I'm not sure what kind of three-dimensional surface lets you walk one more degree of latitude north, and end up eighty-nine degrees south, but it sure ain't a sphere. And I'm reasonably sure KSP doesn't flub up the latitude the way it does the longitude.

[Heimdall5008]

I'm not sure what kind of three-dimensional surface lets you walk one more degree of latitude north, and end up eighty-nine degrees south, but it sure ain't a sphere. And I'm reasonably sure KSP doesn't flub up the latitude the way it does the longitude.

I'm also no aware of such a surface, but depending how it is implemented it could be just a computing error (overflow or so). I have made a custom Google Maps some time ago and it was definitly possible to get values above 90° on the latitude . Sure this is only due to the Mercartor projection, that gets really messy at the poles (at least for a numeric calculation).

But yes, the problem for the longitude seems way more likely. Also I have not noticed such an error in my game.