topic Re: Projection Problem in Data Management Questions

Projection Problem

AlexanderPugliese — Thu, 03 Dec 2015 21:53:48 GMT

I just uploaded a bunch of points using the display XY data in the following format:

Lat: 38.655666 Long: -122.793479

No matter what projection I originally set everything to it always projects into the ocean. All the points seem to be accurate and when I search the lat/long in google earth they are accurate so I'm a bit lost atm.

I've set the data frame coordinate system to the same system I am using on my layer. I've tried everything from adding the data in a current ArcMap document to a brand new one and I keep getting the same results.

Does anyone have any suggestions?

Thanks!

~alex

Re: Projection Problem

DarrenWiens2 — Thu, 03 Dec 2015 21:55:57 GMT

No matter what projection I originally set

Those are Lat/Long, so your original coordinate reference system for the point(s) should be geographic, not projected. Try WGS84 as a default, or other if you know.

Re: Projection Problem

nasiaqureshi — Thu, 03 Dec 2015 22:45:18 GMT

Hi Alex,

I tested out your point in ArcMap and it landed in California. Is this correct? just make sure your settings is in decimal degrees when you got to plot your points. Good Luck,

Re: Projection Problem

DanPatterson_Retired — Thu, 03 Dec 2015 23:01:47 GMT

And an oft mixed up thing when adding event layers... X is longitude and Y is latitude

Re: Projection Problem

DEAF_PROBERT_68 — Fri, 04 Dec 2015 01:26:33 GMT

@ Dan Patterson yes it always does messed up our brains !!!!

Re: Projection Problem

DanPatterson_Retired — Fri, 04 Dec 2015 01:53:01 GMT

Because people still say "latitude - longitude" for historic and non-geometric reasons.

I will give this reference since it is very complete as to how this travesty (my comment) occured and how it has been perputuated and actively endorsed for a variety of which are largely insane (ok...that was a comment).

http://stackoverflow.com/questions/7309121/preferred-order-of-writing-latitude-longitude-tuples

Most of the original references are in there and it will save me time in looking up the missing.

Now don't get me started on why it is ... X-Y ... Easting-Northing (or is it the other way around??? gosh) or Define Projection vs Project

I am sure the nomenclature originated with the same desire for obfuscation.

Re: Projection Problem

NeilAyres — Fri, 04 Dec 2015 07:06:49 GMT

Good one Dan...

When preparing a table for storing these sort of values, I always call the 2 coordinate fields :

XLong, YLat.

Re: Projection Problem

AlexanderPugliese — Mon, 07 Dec 2015 16:29:35 GMT

This was the fix and I am an idiot!

Thanks so much for your time!

~alex

Re: Projection Problem

VinceAngelo — Mon, 07 Dec 2015 23:10:18 GMT

I try to spell out "Longitude" and "Latitude", or use 3-character abbreviations (which won't collide with a datatype reserved word in any platform). Where possible, I try to include units as a postfix or prefix (e.g., "LatitudeDD", "DMS_Lon",...). Using "Long" causes me to break out in hives (same as with spaces in directories). I suppose "LonX" and "LatY" wouldn't require benedryl, but it might be a close thing.

- V

Re: Projection Problem

NeilAyres — Tue, 08 Dec 2015 13:23:01 GMT

Vince,

the Fields XLong & Ylat would be reserved exclusively for real numbers.

If I was storing DMS or some other format of notation, I tend to make it obvious in the attribute name that it is TEXT, like

XLongDMSText or something.

Re: Projection Problem

RobertBorchert — Tue, 08 Dec 2015 13:46:43 GMT

Try this. start a blank MXD session. Add only the XY table and create the event from the XY. Then export that to a database that's in the projection you want.

When using decimal degree data it seems to default to the proper projection for displaying the raw data.

I just did it with the xy you posted and it comes up as Alexander Valley School.

Re: Projection Problem

RobertBorchert — Tue, 08 Dec 2015 13:47:53 GMT

Or more specifically it appears to be on the roof of the school