Geocoding by Coordinates in ArcGIS 9.0

By CAST

What happens if you need to show points on a map and all you have is the latitude and longitude. No shapefiles, no geometric data, nothing ready for a GIS. All you have is a table like the one below.

ADV	LAT	LON	TIME	WIND	PR	STAT
1	9.7	-29.1	09/02/21Z	25	1009	TROPICAL DEPRESSION
2	9.8	-29.4	09/03/03Z	25	1009	TROPICAL DEPRESSION
3	10	-30.7	09/03/09Z	35	1005	TROPICAL STORM
4	9.6	-32.9	09/03/15Z	40	1003	TROPICAL STORM
5	8.9	-34.6	09/03/21Z	45	1000	TROPICAL STORM
6	9.1	-35.8	09/04/03Z	45	999	TROPICAL STORM
7	9	-37.4	09/04/09Z	50	997	TROPICAL STORM
8	8.9	-38.9	09/04/15Z	50	997	TROPICAL STORM
9	9.1	-40.8	09/04/21Z	50	994	TROPICAL STORM
10	9.4	-42.2	09/05/03Z	60	991	TROPICAL STORM
11	9.7	-44.3	09/05/09Z	65	987	HURRICANE-1
12	9.9	-46	09/05/15Z	75	980	HURRICANE-1
13	10.1	-46.6	09/05/17Z	100	960	HURRICANE-3
14	10.4	-47.7	09/05/21Z	110	950	HURRICANE-3

If you have coordinates in latitude/longitude, UTM, State Plane or some other recognized coordinate system ArcGIS can turn the text data into a spatial data layer.

Certain data sources are available as tables or spreadsheets, such as you find in Excel.  You may even find data in a table on the internet that you can copy into a text format or Excel.  In order to geocode you will need (x,y) coordinates of your locations in some sort of tabular form. In the table you are using, you must have a field for your x and y coordinates for each point you are mapping.

Note: ArcMap can read tables in numerous formats. In the future if you have a table in Excep save your table as a DBF 4(*.dbf , DBASE IV) or text tab delimited (*.txt).

In this tutorial you will be taking the coordinates tracking Hurricane Ivan (September 2 – September, 26 2004) across the Atlantic Ocean , into the Gulf of Mexico , to its landfalls. You will be provided with the data.

First you need your data! Go to the Hurricane Ivan data , and save it to your computer (where you'll remember its location!)

Next, we need base maps. Open ArcMap and click the “Add Data” button.

Go to C: ESRI\ESRIDATA\WORLD and select country.shp.
Note: You may not have this data on your local disk C drive ... but your faciliatator should have the data on DVDs provided by ESRI (the same DVD set that has the StreetMap Data). You can then use this data to add files from the World folder.

Now click on the Add Data button again and this time browse to C: ESRI\ESRIDATA\USA and select states.shp.

Now you have both your base maps in place

Zoom in to the area shown below.

Geocoding

So far you have just got your base maps set up. This section will show you the actual geocoding processes.

Go to the Add Data button in ArcMap. Browse to your track_dat.txt and click OK.

Right-Click on track_dat.txt in the layers column and select

“Display X Y data”

 

Make sure your X field is Longitude or (Lon) and your Y field is Latitude (Lat).

Notice that the Spatial Reference System is Unknown. Click the Edit button.

The data that was provided with this tutorial is in a Geographic projection (latitude and longitude) and North American Datum 1983 (NAD83).

Click Select.

Select Geographic Coordinate Systems.

Select North America

Select North American Datum 1983. Click Add. Then click OK in the Spatial Reference Properties window.

Then Click OK in the Display XY Data window.

Your data should appear in over the base map as shown below.

You can use this process to geocode any coordinates – so long as you know which coordinate system and datum the data is in. You should be able to find out this information in the same location as where you got your data from. What happens if you need to show points on a map and all you have is the latitude and longitude. No shapefiles, no geometric data, nothing ready for a GIS. All you have is a table like the one below.

 

Provided by your Geospatial Support team from:
Center for Advanced Spatial Technologies (CAST)
University of Arkansas