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converting txt file with point data to rast...   Basanta Dhungana Jan 02, 2004
Re: converting txt file with point data to...   Christoph Fischer Jan 05, 2004
Re: converting txt file with point data to...   Basanta Dhungana Jan 05, 2004
Re: converting txt file with point data to...   Premkrishnan Radhakrishnan Jan 05, 2004
Re: converting txt file with point data to...   Basanta Dhungana Jan 05, 2004
Re: converting txt file with point data to...   Premkrishnan Radhakrishnan Jan 08, 2004
Re: converting txt file with point data to...   Basanta Dhungana Jan 08, 2004
Re: converting txt file with point data to...   Premkrishnan Radhakrishnan Jan 08, 2004
Re: converting txt file with point data to...   Basanta Dhungana Jan 08, 2004
Re: converting txt file with point data to...   Kenneth Hudak Jan 23, 2006
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Subject converting txt file with point data to raster (grid) data 
Author Basanta Dhungana 
Date Jan 02, 2004 
Message I have a text file (monthly temperature for 12 months) with point data including longitude and lattitude information. I want to interpolate this point data to raster (grid) data at ground scale of 30mX30m resolution. My ultimate objective is to overlay this data to other data set (land use data) which is available at 30m X 30m grid of ground scale resolution in .adf format and is georeferenced to UTM Zone 16 NAD 83 GRS 1980. Your help is highly appreciated. 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Christoph Fischer 
Date Jan 05, 2004 
Message Hello
I would do it like this
1. Convert the textfile to a table using MSExcell
2. Add the table to ArcMap
3. Create a point shapefile from the table using Tools->Add XY data
4. Project the lat-long shapefile to utm
5. Interpolate the projected point-shapefile to a raster using Spatial Analyst. The zvalue is the monthly temperature

I hope it helps

Christoph 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Basanta Dhungana 
Date Jan 05, 2004 
Message Hi,
When I add table from file menu in ArcMap, it does not read the decimal numbers in longitude and lattitude column of my dbf file. For example, it reads lat 38.38 as 38 (meaning rounded all the decimal points). But when I checked my dbf file in MSExcel, all the decimals are preserved. It means, I am saving my original text file as dbf file correctly. The problem is with the ArcMap that opens table layer with all decimal values in lon and lat column rounded. I appreciated your help. 
  normals-gdd.txt (opens in new window)
 
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Subject Re: converting txt file with point data to raster (grid) data 
Author Premkrishnan Radhakrishnan 
Date Jan 05, 2004 
Message Sometimes the saved dbf file is not exactly right
Try increasing the column size of the file in excel and resaving it
Ive had this problem before. Just drag the size of the colums with the lat/longs to make it fit the column and then some more
Another thing you could check is to see if the format of all the numbers in that column is Number with two decimal places instead of General

 
  cheers

Prem Radhakrishnan
Co-founder
39 Degrees North LLC
http://39dn.com 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Basanta Dhungana 
Date Jan 05, 2004 
Message Thanks a lot, stretching the column size works to read decimal points in ArcMap. I have another related problem to display my data.

1. Now I have two files: point layer files for temperature which is created following your suggestion above. Another is raster data for land use. Both files are saved as .lyr and have the same projection method.

2. When I add both files as features in ArcMap layers, the point file only shows single points. I also try to overlay points over raster map by activating both layers, but point layer file does not display. When I activate only point layer file, it only shows single point again.

3. after going back to view the file in ArcCatelog preview, point file shows all data points as desired.

Thanks a lot in advance for your help.
 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Premkrishnan Radhakrishnan 
Date Jan 08, 2004 
Message I have seen this before too. The problem is that the layer is zoomed out way too much.
If you have an another layer which covers the same area as your points add that in and zoom to that layer and you should be able to see all the data points
THe points are there just not displaying right

You also want to check your points to see if there are any null values in your table that makes the points (X and Y Field) 
  cheers

Prem Radhakrishnan
Co-founder
39 Degrees North LLC
http://39dn.com 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Basanta Dhungana 
Date Jan 08, 2004 
Message Hi Prem Krishnan,

I tried as you suggested recently but does not work. Let me explain more.

I have point shape files with same projection as landuse map (raster). If I put each in different data frame, I can display both map separately. But when I keep both map layers in the same data frame, land use map and only one point from shape file are displayed in two different location in layout view.

I have let you access to my data in my following web directory if you want to look at since file is too big to attach:

https://netfiles.uiuc.edu/dhungana/shared/

file folder: LandUse (Zipped need to be unzipped)

Under this file folder, lcoi_99-00b is a land use map (raster file)

The file name "gdd-normals" is a point shape file that I created using ArcMap using the same projection as of land use raster file. I am looking forward to hear if you be able to figure out what actually causing this problem. Thanks a lot. 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Premkrishnan Radhakrishnan 
Date Jan 08, 2004 
Message When I add the data to a new map document (the point file and the landuse) it comes up just fine with all the points and the landuse map


 
  cheers

Prem Radhakrishnan
Co-founder
39 Degrees North LLC
http://39dn.com 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Basanta Dhungana 
Date Jan 08, 2004 
Message Hi Premkrishnan,
I can also display point shape file with undefined coordinate system and raster file within the same data layer. But when I project the coordinate system to mach that of Land use map I can not display point shape map and raster map. But they can be displayed individually in separate data frame.

I have also small request can you try if you can interpolate my point shape map to raster using spline method. I got "operation failure" error message.

Thanks a lot.

 
   
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Subject Re: converting txt file with point data to raster (grid) data 
Author Kenneth Hudak 
Date Jan 23, 2006 
Message So when we add XY data to a map from lat/long table, is the projection always UTM? I've always had that question about plotting raw points on the map.

Ken