xy event layer point results are in a straight line, not a grid

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08-02-2012 07:11 AM
PamFroemke
New Contributor
I'm trying to use the XY Event Layer tool to convert lat/longs in a csv file to a grid of points in ArcMap 10.0. What I'm getting are the points all in a straight (or curved) line. I've tried specifying different projections, but have only succeeded in getting a curved line instead of a straight one. What I want is a grid of points covering the US that I can then convert to a raster.
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8 Replies
DanPatterson_Retired
MVP Esteemed Contributor
a sample of the csv file would be useful in tracking down an answer
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PamFroemke
New Contributor
Oh, of course.........that's what I get for being in a hurry.
Here is the csv file. I'm thinking I don't have the lat/longs in decimal degrees. I haven't determined what they are though.
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JonathanQuinn
Esri Frequent Contributor
The latitude and longitude values you have are in decimal degrees, so choose Geographic Coordinate System > World > WGS 1984 for the coordinate system when using the Display XY Events function.
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PamFroemke
New Contributor
That was one of the things I tried and still ended up with the points all in a straight line, out in the Atlantic Ocean.
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JonathanQuinn
Esri Frequent Contributor
Ohhh sorry, I misinterpreted what you were saying.  Why don't you use the Create Fishnet tool instead?  ArcMap is just placing points in relation to where the coordinates are for those points.  The fishnet tool will create a grid, and you can choose to have a template extent, (the boundary of the United States), and choose to create label points.  I'm not sure how you need your grid to look or lay on the map, but the fishnet tool is what you should probably use.
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PamFroemke
New Contributor
I hadn't heard of this tool. It appears that it doesn't accept a text file input of specific lat/longs, though.
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JonathanQuinn
Esri Frequent Contributor
So those points that you have in your table are the points you'd like in your grid.  How did you generate them?  The values are decimal degrees, and using the Display XY function places them where they should go.
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DanLee
by Esri Regular Contributor
Esri Regular Contributor
Hi Pam,

The lat/long values in your txt file don't form grids. If you need grids to cover certain area, Create Fishnet tool is good to use. Here is an exercise you can try to create a grid for the US:

- Run the Create Fishnet tool using the parameter values shown in the attachment. Your should get a line and a point outputs. These output will have "Unknown" coordinate systems.
- Run the Define Projection tool (Data Management toolbox - Projection toolset) on the line or point output and use "GCS_North_American_1983" or a desired projection as the Coordinate System. You should get the grid lines and points as shown in the attachment.

Hope that helps you to understand the Create Fishnet tool. You can then play with the parameters to get exactly what you neet.
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