count number of raster cells of different values inside  polygon fishnet

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5
03-30-2011 03:14 PM
TiffanyDuhl
New Contributor
Hi,

I'm wanting to perform an operation that is similar to running zonal statistics, but I'm working with a raster that contains categorical values, so mean, range, and even variety are not useful to me.  I want to count the number of raster cells of each value within a set of equal-area polygons (my domain grid)... I've seen an older thread that recommends converting said raster into polygons, intersecting with the polygon grid (my "zone" dataset), then running Calculate Areas... but frankly, I'm working with 30-m resolution data and my machine keeps crashing out because this results in hundreds of millions of polygons (even if I don't conform to the original raster cell boundaries).

Does anyone out there know if there's an easier way to do this?

Thanks!
-Tiffany
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5 Replies
EricRice
Esri Regular Contributor
Tiffany,

Check out the Zonal Histogram tool.

Regards,
Eric
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NawajishNoman
Esri Contributor
Hi Tiffany,

Please also look at the Tabulate Area tool. This tool calculates cross-tabulated areas between two datasets and outputs a table. See Working with Tabulate Area for additional information.

Thanks,

Nawajish Noman
Esri
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VickyP
by
New Contributor
Hi Tiffany,

   I want to create polygons from Point Feature class using Model Builder, but I have not find the way to do it, Did you find it? If yes, then please share with me, I have Grid Data in a shape file, I have created point feature class from that Grid Data now I have to create polygons from those points, also I have to display a symbology that is set in the ArcMap for the various points.

   As u have written below that you have seen an older thread that that recommends running Calculate Areas, I also want to calculate the area of the polygons please share me the url of that thread.



Hi,

I'm wanting to perform an operation that is similar to running zonal statistics, but I'm working with a raster that contains categorical values, so mean, range, and even variety are not useful to me.  I want to count the number of raster cells of each value within a set of equal-area polygons (my domain grid)... I've seen an older thread that recommends converting said raster into polygons, intersecting with the polygon grid (my "zone" dataset), then running Calculate Areas... but frankly, I'm working with 30-m resolution data and my machine keeps crashing out because this results in hundreds of millions of polygons (even if I don't conform to the original raster cell boundaries).

Does anyone out there know if there's an easier way to do this?

Thanks!
-Tiffany
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IanJohnson
New Contributor
Hi,

I'm wanting to perform an operation that is similar to running zonal statistics, but I'm working with a raster that contains categorical values, so mean, range, and even variety are not useful to me.  I want to count the number of raster cells of each value within a set of equal-area polygons (my domain grid)... I've seen an older thread that recommends converting said raster into polygons, intersecting with the polygon grid (my "zone" dataset), then running Calculate Areas... but frankly, I'm working with 30-m resolution data and my machine keeps crashing out because this results in hundreds of millions of polygons (even if I don't conform to the original raster cell boundaries).

Does anyone out there know if there's an easier way to do this?

Thanks!
-Tiffany


I'm sure you've already conquered your question by now, but for any future people users looking at this thread I would recommend using the Geospatial Modeling Envrionment (GME- Formerly "Hawth's Tools"). This environment  contains the command "isectpolyrst" which will do exactly what you are asking. It also provides more functionality than the similar ARC tools as it has the ability to work with multipart feature. If you look at the similar tool in the help section (http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00300000000t000000.htm) you can see some of the limitations of the extract values by polygon.

Best,

Ian
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VickyP
by
New Contributor
Hi Ian,

   I have solved my problem using ArcObjects 9.3, basead on spatial query that I was doing, that query was returning me the records, that was nothing but the records in Fishnet polygon shape file, as I know the area of each cell and it is also fixed area for example 50 x 50, I just added the area of all the records that I am getting from the query, then I can show that total area to the user.
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