Raster to polygon problems

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04-25-2012 12:23 PM
grahamlangley-edwards
New Contributor II
Hi, I am trying to convert a raster to polygon in ArcGIS 10.  I initially used the Extract by Attributes tool to isolate elevation ranges between 1900 and 3800 meters from a 90m DEM.  I want to convert that into a polygon that I can use to clip an area of interest from some satellite tiles.  When I convert from Raster to Polygon I get a grid instead of a polygon (Screenshot2).  I also included an up close shot of the grid (Screenshot).  I'm not sure why this is happening.  The only options I have are to change the field parameter from Value to Count, but that also returns a grid structure.  How can I create a regular polygon from this data?  Any help is greatly appreciated....

Thanks,

Graham
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by Anonymous User
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Original User: dkwiens

Either:
1.) reclassify your raster so that all of the values between 1900 and 3800 have the same value, then convert the cells with that value to a polygon.
or...
2.) make a dummy column in the polygons you have now, make it equal the same value for all polygons, then Dissolve them all into one big polygon based on that column
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grahamlangley-edwards
New Contributor II
Darren,

Thanks for your reply!  I chose option 2, as it seemed a little more straightforward, and it worked perfectly.  I appreciate your time.

Thanks again,

Graham
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by Anonymous User
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Original User: curtvprice

I want to convert that into a polygon that I can use to clip an area of interest from some satellite tiles.


Seems to me a more direct approach would to create a mask using the Set Null tool - and then use Extract By Mask. (No need to create polygons that way.)

As they say, raster is faster, but vector is correcter.
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