topic Re: display xy points at correct location in Data Management Questions

display xy points at correct location

panlu — Wed, 28 Jan 2015 17:44:36 GMT

I have the data downloaded on-line and have no idea about the original coordinate system. I observed the x and y values, they looks like in meters,

The latitude is something like: 468769600, and longitude like: -1028108400. the points should located in ND, and I tried UTM14N and WGS1984 none of them works. Any help would be appreciated. Many thanks

Re: display xy points at correct location

JoeBorgione — Wed, 28 Jan 2015 17:53:36 GMT

Just a guess: check for a ND state plane coordinate system....

Re: display xy points at correct location

XanderBakker — Wed, 28 Jan 2015 18:03:12 GMT

I think you an issue with the decimal sign of the coordinates. If your x-coord (longitude) is expressed in meters, it would be like 25-26 times the circumference of the world. That doesn't make sense.

Re: display xy points at correct location

panlu — Wed, 28 Jan 2015 18:07:12 GMT

tried but still not work. There are several outliers (with 0 Lat/Lon values) I don't know if those can cause trouble

Re: display xy points at correct location

panlu — Wed, 28 Jan 2015 18:17:46 GMT

Yes, you are right. the values in my table looks like in a unit of cm. What coordinate system would generate CM values?

Re: display xy points at correct location

DarrenWiens2 — Wed, 28 Jan 2015 19:19:50 GMT

I don't think you can determine the unit by the magnitude of the coordinates. They are just numbers - you could make a custom coordinate system with the origin 1,000,000 times the circumference of the Earth away from your data. How did you decide that your unit is cm, other than they are large numbers?

Where did you download this data from? There was surely metadata.

Re: display xy points at correct location

MelitaKennedy — Wed, 28 Jan 2015 20:15:10 GMT

Weirdly enough, these might be scaled latitude and longitude.

Original:

latitude: 468769600

longitude: -1028108400

If I divide by 10000000,

latitude: 46.8769600

longitude: -102.8108400

which certainly fits North Dakota.

Re: display xy points at correct location

panlu — Wed, 28 Jan 2015 20:56:02 GMT

Yes, you are life saver. After I divide by 10000000, they are mapped at correct locations. Thanks a lot!!

Re: display xy points at correct location

XanderBakker — Wed, 28 Jan 2015 20:59:09 GMT

pan lu‌, could you mark the thread as answered? In the lower left corner of Melita's post, there should be a button "Correct Answer".

Re: display xy points at correct location

panlu — Wed, 28 Jan 2015 21:17:06 GMT

Thanks, I could not see the button earlier. Done now.

Re: display xy points at correct location

JoeBorgione — Wed, 28 Jan 2015 21:58:15 GMT

Good catch Melita! I used to have a system that did that same sort of calculation to put the intersection of the Prime Meridian and the Equator in Murray, Utah. And on top of that, it would split things into quadrants where the NW was -X, +Y; NE was +X +Y; SE was +X, -Y; SW was -X,-Y.

I'd look at the coordinate values with a mirror while standing on my head to figure them out...