topic Re: New XY layer from Lat Long (DD) not plotting correctly in Geoprocessing Questions

New XY layer from Lat Long (DD) not plotting correctly

AlanMcCarthy — Wed, 19 Jun 2013 14:26:50 GMT

Hi,

I'm trying to create a new point layer from some Lat and Long coordinates that I have in a table (exp. 44.809662,-73.087322
). I used "Make New XY Event Layer" to plot the points. I have some town parcel layers and the point locations are all from within the parcels so the new point layer should be overlapping the parcels. However, they aren't even close!! I thought it might have been my Lat Long Coordinates so I took Lat Long coordinates from five random locations in the area using Google Maps, imported them into ArcMap as an Excel file and tried again. They all showed up really far away also! Their spatial spread looks correct but they aren't close to the parcel layers.

The projection system and the coordinate systems are the same so I'm not sure what's wrong. Any ideas?

Thanks,
Alan

Re: New XY layer from Lat Long (DD) not plotting correctly

MelitaKennedy — Wed, 19 Jun 2013 16:49:16 GMT

Hi Alan,

I can think of two possibilities. Are you equating X = longitude and Y = latitude?

When using the Add XY tool, you need to assign the data's current coordinate system. The tool will default to the data frame's coordinate system. Because your points are in lat/lon, you need to assign the appropriate geographic coordinate system.

Melita

Re: New XY layer from Lat Long (DD) not plotting correctly

AlanMcCarthy — Wed, 19 Jun 2013 17:17:48 GMT

Hey Melita,

Yeah the Lat and Long are being equated with the correct locations. I'm also assigning the spatial reference to be the same as the parcel layers I have displayed. After the layer is made sure the Projected Coordinate System, Projection, Geographic Coordinate System and Datum are the same between the points layer and the parcel layers. The data frame coordinate system I've changed to be the same as all the other layers as well.

-Alan

Re: New XY layer from Lat Long (DD) not plotting correctly

MelitaKennedy — Wed, 19 Jun 2013 19:15:46 GMT

Hi Alan,

Umm, but what coordinate systems are your parcel layers using? Usually they're using a projected one. The XY data is lat/lon. You have to assign the appropriate geographic coordinate system, then ArcMap will project it on-the-fly to match the data frame's coordinate system. At that point, you can export the layer to a feature class and use either the source/native coordinate system or the data frame's.

Melita

Re: New XY layer from Lat Long (DD) not plotting correctly

AlanMcCarthy — Thu, 20 Jun 2013 12:38:59 GMT

Hi Melita,

I'm afraid that I might not be as familiar with some things about projections as I should, but I think I understand. So I apologize if I have some redundant responses.

When I open up the Layer Properties, in the Source Tab for the parcel layer it says "Projected Coordinate System: NAD_1983_StatePlane_Vermont_FIPS_4400". All my other layers also say this in their Source Tabs. Including the point layer I made using "Make XY Event Layer". When using that tool, I set the spatial reference(the option at the bottom) to the Projected Coordinate System: NAD_1983_StatePlane_Vermont_FIPS_4400.

The Geographic Coordinate System I didn't specify when creating the point layer but it was automatically set to Geographic Coordinate System: GCS_North_American_1983, which is the same as all the other layers.

I've noticed that the Data Frames Projected Coordinate System is WGS_1984_Web_Mercator_Auxiliary_Sphere and it's Geographic Coordinate System is Geographic Coordinate System: GCS_WGS_1984.

-Alan

Re: New XY layer from Lat Long (DD) not plotting correctly

AlanMcCarthy — Thu, 20 Jun 2013 12:43:26 GMT

Melita,

I just changed the Data Frame Projection Coordinate System and Geographic Coordinate System to the NAD_1983_StatePlane_Vermont_FIPS_4400 and GCS_North_American_1983 but that didn't change where my plotted points were. They are still appearing really far away from the parcels.

-Alan

Re: New XY layer from Lat Long (DD) not plotting correctly

AlanMcCarthy — Thu, 20 Jun 2013 13:37:05 GMT

Hi Melita,

Soooo, I'm not positive on what happened but I think I fixed it. In arc catalog or by the Define Projection tool I changed the Geographic Coordinate System for the point layer to World WGS_1984. This made the points show up on my parcel layer! In the sources tab though I don't see a projected coordinates system anymore. Maybe it's using the one specified in the Data Frame then?

Lastly, since I was messing with the Data Frame projections should I expect things to be really messed up now. Everything looks good but when I add new layers sometimes a pop up saying that the layer has a different coordinate system than the data frame appears. Should I just always change the layers coordinate system to match the data frame or let it be?

-Alan

Re: New XY layer from Lat Long (DD) not plotting correctly

MelitaKennedy — Thu, 20 Jun 2013 19:29:54 GMT

Hi Alan,

ArcMap has the ability to convert (project!) in-memory between different coordinate systems. To do so, it needs to know both the source and target coordinate systems. The layers or data are the sources. The target is the data frame's coordinate system. You need to leave the layer coordinate system definitions alone. They identify the current reference frame that the data is georeferenced to. If you want to create a copy of the data referenced to a different coordinate system, use the Project Tool.

The warning you're getting is specifically about having different geographic coordinate systems (also know as datums). Even if the data frame or a layer is georeferenced to a projected coordinate system, the projected coordinate system is based upon a geographic coordinate system.

One way to look at it--a geographic coordinate system identify the size and shape of the model of the Earth and where the latitude and longitude lines area. A projected coordinate system converts from this 3D system into a flat plane.

The same location on the ground will have different latitude-longitude values depending on which geographic coordinate system is used. The warning is that there are different geographic coordinate systems in use, and you may need to set some geographic (datum) transformations to reconcile them. The reason that we don't automatically apply geographic transformations is that there are often multiple ones per pair of geographic coordsys or a more accurate transformation may be to use two transformations that convert through a 3rd GCS! Starting at 10.1, we now present a sorted list of transformations in the data frame properties, coordinate system tab, transformation dialog.

Melita

Re: New XY layer from Lat Long (DD) not plotting correctly

OliviaDeSimone — Fri, 31 Jan 2014 00:04:15 GMT

Hi,

I am sorry to revive this question after its already been resolved, but I am having this same issue. I understand that having the geographic coordinate systems and projected coordinate systems match between shapefiles does not necessarily mean that they will align properly. However, I am not sure how to fix the problem so that they do align correctly.

I have lat and long coordinates in an excel file, and I am using Create Feature Class from XY Table in ArcCatalog to create the points. The other shapefiles I am working with use GCS_NorthAmerican_1983 and are projected into NAD_1983_StatePlane_Pennsylvania_South_FIPS_3702_Feet. What steps should I take to having my lat and long points properly align?

Thank you!

Re: New XY layer from Lat Long (DD) not plotting correctly

OliviaDeSimone — Fri, 31 Jan 2014 00:23:48 GMT

Re: New XY layer from Lat Long (DD) not plotting correctly

OliviaDeSimone — Fri, 31 Jan 2014 00:33:36 GMT

Here is some additional info.

I am trying to match my lat/long coordinates to a street centerline shapefile with GCS_NorthAmerican_1983 as its geographic coordinate system and NAD_1983_StatePlane_Pennsylvania_South_FIPS_3702_Feet as its project. The extent of this shapefile is as follows:

Top: 433375.665652 ft
Bottom: 382085.723941 ft
Right: 1379567.124976 ft
Left: 1316692.322576 ft

My lat/long coordinates which have the same geographic coordinate system and projected coordinate system has the following extent:

Top: 40.613278 ft
Bottom: 40.518961 ft
Right: -79.971118 ft
Left: -80.141168 ft

Though, now that I type this all out, I see that ArcMap has taken my coordinates and simply converted them into feet. I can't say I understand why this has occurred.

Re: New XY layer from Lat Long (DD) not plotting correctly

MelitaKennedy — Fri, 31 Jan 2014 17:23:03 GMT

Hi Olivia,

When you use the Add XY Data tool in ArcMap, it defaults the data's coordinate system to the same as the data frame's. In this case, as you noticed, the Excel data is in decimal degrees. Import it again, but change the coordinate system in the tool to NAD 1983 (geographic coordinate system) instead.

Melita

Re: New XY layer from Lat Long (DD) not plotting correctly

OliviaDeSimone — Sat, 01 Feb 2014 18:57:01 GMT

Hi Melita,

I just tried again, and when I opened arcMap, I set the data frame to NAD 1983 which is what the lat/long was collected into. It plotted the points in decimal degrees, but it still doesn't align with my city data.

Re: New XY layer from Lat Long (DD) not plotting correctly

OliviaDeSimone — Sat, 01 Feb 2014 19:37:57 GMT

Up until now, I have only been working with 4 lat/long points of my total data set. I just tried plotting all of the data points and the picture that I am adding the this post is what happened. I also added some city data which you can see as the lines shapefile.

[ATTACH=CONFIG]31048[/ATTACH]

Re: New XY layer from Lat Long (DD) not plotting correctly

OliviaDeSimone — Sat, 01 Feb 2014 20:30:09 GMT

Hi again Melita,

I want to thank you for your help. I was just not being thorough enough with my data, and after fixing that, your advice on setting the data frame worked.

I do have my additional question: My data has several additional fields besides just lat and long, and I was encountering an issue where when I added the .cvs file into ArcMap, the field were becoming jumbled. Ie address was under zip code, my Y field disappeared entirely, and the name of the business was located under address. Do you know what might be causing this? I eventually just took the lat/long data and made it its own excel spreadsheet. I am going to set about fixing it now, and I was just planning to import the additional data in a dbf to attach to my newly created point shapefile of the lat/long. I'm hoping this works, but I would like to know how to handle this problem should it arise for me again.

Thank you!