So I've brought this up in the past, but haven't really pursued it to the point where it would finally sink through my skull.
I don't get the difference between the GPS coordinates shown on my GPS units versus the coords shown on Google Earth.
Example:
My GPS shows me these coordinates - N34 25.411 W118 35.647
When I paste them into Google Earth, it takes me to the correct location, but converts the data to these coordinates - 34°25'24.66"N 118°35'38.82"W
So I can take a spot on my GPS and find it on Google Earth, but I can't go the other direction (because GE understands my GPS, but my GPS doesn't understand GE).
Google Earth says that it uses DMS (degree, minutes, seconds). Is there a similar name for the coordinates my GPSs use? Is there a simple setting I can use to make them all use the same type of coordinates?
I'd really like to be able to find a spot on Google Earth and then punch those numbers into my GPS and find the spot.
I'd also like to be able to add more trust and certainty when I swap coordinates with others. For example, the coordinates shown on the Off Road Riding Spots seem to be a mix of coordinates. If I copy/paste the coords for the Husky Monument (N 35 13 12 W 117 19 00) into Google Earth, it takes me to a spot that's close, but not quite the right spot. If I didn't know better (oops, I guess I actually don't know better), I'd follow the coords and not find the spot.
So someone please educate me. I'd like to get straightened out and then maybe do some cleanup in the Riding Spots thread.
Open Google Earth, on the "Tools" drop down menu, select "Options", on the "3Dview" tab under the heading "Show Lat\Long" select the middle choice: "Degrees" it will then display in decimal degrees instead of degrees, minutes, seconds.
tda150 wrote: Open Google Earth, on the "Tools" drop down menu, select "Options", on the "3Dview" tab under the heading "Show Lat\Long" select the middle choice: "Degrees" it will then display in decimal degrees instead of degrees, minutes, seconds.
OK. That helps. On my version of Google Earth (4.2 basic freebie version) the setting is called Degrees, Decimal Minutes. I changed to that setting and now the coordinates on Google Earth are the same as my GPS. Now I'd better check my other GPSs and make sure they're all configured the same as each other.
dedmiston wrote: My GPS shows me these coordinates - N34 25.411 W118 35.647
When I paste them into Google Earth, it takes me to the correct location, but converts the data to these coordinates - 34°25'24.66"N 118°35'38.82"W
N34 25.411 means 34 degrees and 25.411 minutes
34 25 24.66 means 34 degrees 25 minutes and 24.66 seconds
Notice that 24.66 seconds is almost half a minute
So, 24.66/60 is .411
25.411 minutes is the same as 25 minutes and 24.66 seconds
This is right and a part of the problem.
The rest of the issue is very complex and involves application/conversion issues of Datums and Map Projections. Simple answer is that it is near statistically impossible for two recreation level GPS units to arrive at the exact same coordinate pair calculations in this situation. GE uses many sources for data that are in many different datums and map projections -it is all converted mathematically into one Datum/map projection combination for display/use. Your GPS unit use WGS84 datum for the positional fix calculation then uses software to convert this grid calculation into the DMS form in the Datum and Map Projection you have chosen for display output. Each of these calculations introduces accuracy error on top of the accuracy variability inherent in recreation/resource grade GPS equipment.
To increase your personal GPS to GE overlay accuracy make sure you are using the same Datum and map projection parameters on both data sources when they need to interact.
dedmiston wrote: My GPS shows me these coordinates - N34 25.411 W118 35.647
When I paste them into Google Earth, it takes me to the correct location, but converts the data to these coordinates - 34°25'24.66"N 118°35'38.82"W
N34 25.411 means 34 degrees and 25.411 minutes
34 25 24.66 means 34 degrees 25 minutes and 24.66 seconds
Notice that 24.66 seconds is almost half a minute
So, 24.66/60 is .411
25.411 minutes is the same as 25 minutes and 24.66 seconds
This is right and a part of the problem.
The rest of the issue is very complex and involves application/conversion issues of Datums and Map Projections. Simple answer is that it is near statistically impossible for two recreation level GPS units to arrive at the exact same coordinate pair calculations in this situation. GE uses many sources for data that are in many different datums and map projections -it is all converted mathematically into one Datum/map projection combination for display/use. Your GPS unit use WGS84 datum for the positional fix calculation then uses software to convert this grid calculation into the DMS form in the Datum and Map Projection you have chosen for display output. Each of these calculations introduces accuracy error on top of the accuracy variability inherent in recreation/resource grade GPS equipment.
To increase your personal GPS to GE overlay accuracy make sure you are using the same Datum and map projection parameters on both data sources when they need to interact.
This is a common issue in the mapping profession.
Map Guy
I'll bet you got all warm inside when this question was asked. Didn't you?
dedmiston wrote: My GPS shows me these coordinates - N34 25.411 W118 35.647
When I paste them into Google Earth, it takes me to the correct location, but converts the data to these coordinates - 34°25'24.66"N 118°35'38.82"W
N34 25.411 means 34 degrees and 25.411 minutes
34 25 24.66 means 34 degrees 25 minutes and 24.66 seconds
Notice that 24.66 seconds is almost half a minute
So, 24.66/60 is .411
25.411 minutes is the same as 25 minutes and 24.66 seconds
This is right and a part of the problem.
The rest of the issue is very complex and involves application/conversion issues of Datums and Map Projections. Simple answer is that it is near statistically impossible for two recreation level GPS units to arrive at the exact same coordinate pair calculations in this situation. GE uses many sources for data that are in many different datums and map projections -it is all converted mathematically into one Datum/map projection combination for display/use. Your GPS unit use WGS84 datum for the positional fix calculation then uses software to convert this grid calculation into the DMS form in the Datum and Map Projection you have chosen for display output. Each of these calculations introduces accuracy error on top of the accuracy variability inherent in recreation/resource grade GPS equipment.
To increase your personal GPS to GE overlay accuracy make sure you are using the same Datum and map projection parameters on both data sources when they need to interact.
This is a common issue in the mapping profession.
Map Guy
My brain hurts and I knew what you were talkign about.
"Honey, are the brakes suppose to touch the floor"
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