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I have 1000's of data point I need to convert from North Central Texas 4202 into Lat/Long decimal degrees. Can someone give me a conversion equation so I can quickly convert using excel? I have only been able to find online conversion calculator which convert one entry at a time. This is not time efficient for me. Please help!

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Can you provide a link to the calculator you found? I should be able to pull the formula they use from the code. Also, if you have access to a GIS program, you should be able to plot your coordinates and reproject them into the desired coordinate system and export the table back to an excel sheet. –  egdetti Dec 13 '12 at 18:18
    
earthpoint.us/StatePlane.aspx –  Bret Fischer Dec 13 '12 at 19:10
    
I do have GIS as well. How can I export coordinates to excel? I already know how to reproject into NAD83 decimal degrees. Thank you for your help –  Bret Fischer Dec 13 '12 at 19:11
    
What GIS software and version are you using? –  egdetti Dec 13 '12 at 19:14
    
I am using ArcMap 10.1 –  Bret Fischer Dec 13 '12 at 19:22
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2 Answers

Since you have ArcGIS 10.1 available, it would be easy to import your current data in excel format, plot the XY coordinates in the current coordinate system, reproject your points to your desired coordinate system, and then export the data back to a new spreadsheet.

To do this, follow these steps:

1.) Add your existing spreadsheet to ArcMap

2.) Right click your spreadsheet in the table of contents and select "Display XY Data"

  • Choose the appropriate fields for your X and Y coordinates
  • Under "Coordinate System of Input Coordinates" select "Edit..." and choose the correct coordinate system.

3.) Once your points are plotted, right click your plotted data in the table of contents and select data -> Export Data. Save the plotted points to a shapefile and add it to your map.

4.) Reproject the shapefile to the desired projection.

5.) In the Data Management -> Features toolbox, run Add XY Coordinates on your newly projected shapefile. You may have to rename your existing XY fields if they are named POINT_X and POINT_Y, as these are the field names the tool uses. This will add the XY coordinates in the new coordinate system to your attribute table.

6.) Open the attribute table of your shapefile, under table options select Export. Choose an appropriate format and location to save your spreadsheet to.

Voila, you have a new spreadsheet with projected XY data. If your ultimate goal is just to get the data into shapefile format in the correct projection, just do steps 1-4.

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This seems easy enough. I think I am not reprojecting properly. I changed the coordinate system in "data frame properties" from State Plane "4202 US feet" to Geographic NAD83. When I add XY Coordinates the result is still in State Plane XY US feet. My desired result is NAD83 decimal degrees. What am I doing wrong? –  Bret Fischer Dec 13 '12 at 20:04
    
I figured it out. Data Management Tools>>Projections and Transformations>>Project Thanks so much. Your advice was extremely helpful –  Bret Fischer Dec 13 '12 at 20:21
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Assuming that your data is in a csv file (or similar) you can load data using the Load XY data in ArcGIS. From the ArcGIS help (9.3 unfortunately, as I can't find 10):

Adding x,y coordinate data as a layer

  • Click the Tools menu and click
  • Add XY Data. Choose a table that contains x,y coordinate data. If the table is not on the map, click the Browse button to access it from disk.
  • Click the X Field drop-down arrow and click the field containing x-coordinate values.
  • Click the Y Field drop-down arrow and click the field containing y-coordinate values.
  • Click Edit to define the coordinate system and units represented in the x and y fields. The x,y coordinates will be automatically transformed to match the coordinate system of the data frame.
  • Click OK.
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