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I am working with multiple raster files that cover all of united states. The file format of the rasters - GeoTIFF. I have around 100 geotiffs that I need to process. Then I have another shapefile with polygons. What I need to do is extract information (SUM of all values) from the raster files by using the polygon shapes and get data in a table format. I have tried ArcMap 10.3 Spatial Analyst extension's Zonal Statistics (Table) for the SUM, but I was not satisfied with the results - there are way too many 0s in places where there should be some values even if they are small.

I am asking for a good way to extract values in ArcMap, QGIS, possible R or other software. The GeoTIFFS dimensions are 3600 pixels to 859 pixels and they are around 25mb in size (each).

If there any model builder suggestions with functions information that would be great!

  • Is this what you are looking to do: stackoverflow.com/a/14687110/1446289? – Aaron Apr 14 '15 at 20:53
  • "I want to take polygon[i] overlay it on raster[i], extract and sum the values from raster [i]" up to here. Looking for a way to do all layers automatically. I am not very familiar with R, only used it for simple calculations, never rasters. – Marik Apr 14 '15 at 21:00
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    Regarding Zonal Stats: Note that if a polygon is smaller than the raster cells resolution, it will not produce statistics. To overcome such an issue, you might want to use the buffer tool to enlarge them. In order to extract a raster using a polygon overlay you should use Extract By Mask. – dof1985 Apr 14 '15 at 21:29
  • majority of the polygons are larger than individual raster cells. If the polygon covers a raster only partially, will it extract the value of that cell? some of the polygons are narrow and spread over several raster cells but they do not contain them entirely. – Marik Apr 14 '15 at 22:06
  • That is potentially part of your problem. There is an internal vector to raster conversion done when you use polygons as the zones (and a resample occurs when using two rasters that don't match resolutions). To maintain full control over that resampling or rasterization, it's best to do it yourself as a separate step/tool and then use the result as zonal input. Or at least check the environment settings. There are some tips about this in the Zonal stats help file. – Chris W Apr 14 '15 at 23:41
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After clasiification you can Convert Raster to Polygon in Arcgis and then Open the attribute tables to fetch the area of each class of polygons.

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