Converting Gps/map Coordinates

[USNret]

I'm currently on a trip touring around Northern Thailand with my wife. We have a borrowed GPS unit, and use google maps for some of our trip planning. We do not have a smart phone with web capability.

The challenge is that our Garmin GPS does not offer the Thai alphabet, nor can it accept punctuation in the address field when entering destinations. Therefore, it is difficult-to-impossible to enter Thai addresses; either our transliteration to the Roman alphabet is imperfect, or we are unable to enter "/" in the address, and "Address not found" is the normal reply when we try to plot addresses.

We can pan & zoom in the map to locate our destination, if we have enough knowledge of the local area. This is an imprecise & slow method of input considering the ancient nature of our GPS unit.

The 3rd method of entry is by geo-coordinates (latitude & longitude) and this is what we have been using most often, with generally good results.

The problem here is that the Garmin takes coordinate in degrees, minutes, and decimal of minutes (e.g., 19-53.208 N, 99-50.1 E). But google maps gives coordinates in degrees & decimal of degrees (19.8868 N, 99.8350 E). So one would have to accurately convert from one system to the other to enter into the Garmin unit). Some hotels & tourist sites give their geo-coordinates on their website, and I find they often use a 3rd system, which is degrees, minutes, seconds, and decimal of seconds). So we have this array of confusion.

You can convert between the three & I will explain the method. I hope that TV readers will accept this in the helpful spirit in which it is intended. Please do not turn this into a political discussion, or an assessment of my relative personal merits & flaws. For some, the following discussion is self-evident, but others might be even more mathematically challenged than myself and it is for those to whom I hope this is useful. If you find this not useful, please quietly go to another discussion to spew your ire.

First of all, in terms of geographic coordinates, there are 60 minutes in a degree, and 60 seconds in a minute. Also, unless you get into southern Indonesia, all of Asia is in the north latitude and is entirely in eastern longitudes.

Taking my above example of degrees & decimals of degrees (19.8868 N, 99.8350 E), which if you copy & paste into google maps you will see is Central Plaza mall of Chiang Rai, keep the degrees (19) then take the decimal portion of the coordinate (.8868) and multiply it by 60. This gives you 53.208, so the northern coordinate is 19-53.208. Doing the same with the longitude gives you 99-50.1 So, in degrees & minutes, Central Plaza is located at 19-53.208N, 99-50.1E. Also note that the more decimal places you use, the more precise is your location. Generally, 2-3 decimal places is sufficient. By the time you add more decimal places, you are representing accuracy down to a matter of meters which is overkill.

Now, let's say you need to show these same coordinates in degrees/minutes/seconds. You would repeat the same process. Keep the degrees & minutes (19-53), take the decimal portion (.208) and multiply by 60 to get the number of seconds. .208 * 60 = 12.48, so degrees/minutes/seconds of Central Plaza is 19-53-12.48N. Doing the same for longitude is 99-50-06E. Simple, huh?

Now, say you need to convert in the opposite direction. To convert degrees/minutes/seconds (19-53-12.48N) into degrees & minutes, take the seconds part (12.48) and divide by 60. 12.48/60 = .208 so in degrees & minutes this is 19-53.208N. To convert to degrees, take 53.208 & divide by 60 which comes to .8868, so in degrees it is 19.8868N. Bingo!

Hope at least a few of you find this useful.

[Mosha]

My KAMAZ Unit has the conversion between degrees and DMS

[Thanyaburi Mac]

USNret

Where do you find the Lats & Longs on Google Maps? That's one of my few complaints about it, I can't find them.

So, I use Google Earth, note down the Lats & Longs of where I want to go, enter that in my Garmin GPS, and off I go.

I note that with GE you can select the format of the Lat-Long by clicking Tools then Options and View, so I switch back and forth a lot depending on what other source I'm using.

Don't have my Garmin eTrex with me at the moment but seems to me that I can also choose the format in it.

Mac

former Army, not a "Squid"....

[isawasnake]

My KAMAZ Unit has the conversion between degrees and DMS

So does his garmin. Probably

[Sophon]

Where do you find the Lats & Longs on Google Maps? That's one of my few complaints about it, I can't find them.

<snipped>

Place the cursor on a location, right click and select "What's here?". The coordinates will then show up in the search box.

Sophon

[USNret]

Where do you find the Lats & Longs on Google Maps? That's one of my few complaints about it, I can't find them.

<snipped>

Place the cursor on a location, right click and select "What's here?". The coordinates will then show up in the search box.

Sophon

I obviously do it the hard way. When you bring up a map, there is a little link icon on the left side. I click the link icon, and it brings up a couple of text boxes with links to the map page you have created (so you can email the map to someone or embed it in a web page).

I copy the entire first link, paste into Notepad, then you will see the lat/long embedded in the link. Cut out all the extraneous stuff & there you have it.

Or select "what's here" like Sophon said if you're a wimp and want to do it easy. :-)

[doontp]

The Garmin Unit can accept any format. The settings within the unit must be changed.

[Mrjlh]

If you are using Google Earth, Lat/Long is clearly shown at the bottom of the screen where ever the cursor is placed. Also got to "tools"-Options and set the measurement of Lat/Long to whatever you prefer.

Secondly, check the languages on your Garmin in "tools". It may have Thai as a choice and you can also change input to Thai also. But that depends on your model and where it was bought.