topic extraction from raster data by mask in ArcGIS Spatial Analyst Questions https://community.esri.com/t5/arcgis-spatial-analyst-questions/extraction-from-raster-data-by-mask/m-p/317796#M4475 <HTML><HEAD></HEAD><BODY><SPAN>Hi,</SPAN><BR /><BR /><SPAN>I am extracting from a raster data set by mask with a polygon shape file as the mask - but the strange thing is that the masked raster data seems to have changed the values of raster data.&nbsp; For example, I know that within this polygon that there are many zero values, but these all disappear when I mask out the area with the polygon. Can anybody tell me what might be happening here?&nbsp;&nbsp; (by the way, a friend of mine seems to be doing the same thing with the same data, but not does not have the problem).</SPAN><BR /><BR /><SPAN>thanks</SPAN><BR /><BR /><SPAN>eric</SPAN></BODY></HTML> Wed, 27 Jul 2011 19:22:27 GMT EricStrobl1 2011-07-27T19:22:27Z extraction from raster data by mask https://community.esri.com/t5/arcgis-spatial-analyst-questions/extraction-from-raster-data-by-mask/m-p/317796#M4475 <HTML><HEAD></HEAD><BODY><SPAN>Hi,</SPAN><BR /><BR /><SPAN>I am extracting from a raster data set by mask with a polygon shape file as the mask - but the strange thing is that the masked raster data seems to have changed the values of raster data.&nbsp; For example, I know that within this polygon that there are many zero values, but these all disappear when I mask out the area with the polygon. Can anybody tell me what might be happening here?&nbsp;&nbsp; (by the way, a friend of mine seems to be doing the same thing with the same data, but not does not have the problem).</SPAN><BR /><BR /><SPAN>thanks</SPAN><BR /><BR /><SPAN>eric</SPAN></BODY></HTML> Wed, 27 Jul 2011 19:22:27 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/extraction-from-raster-data-by-mask/m-p/317796#M4475 EricStrobl1 2011-07-27T19:22:27Z Re: extraction from raster data by mask https://community.esri.com/t5/arcgis-spatial-analyst-questions/extraction-from-raster-data-by-mask/m-p/317797#M4476 <HTML><HEAD></HEAD><BODY><SPAN>Eric,</SPAN><BR /><SPAN>The values changed due to stretching techniques but the raw data will be the same as the source raster.</SPAN><BR /><SPAN>Regards,</SPAN></BODY></HTML> Tue, 02 Aug 2011 07:46:51 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/extraction-from-raster-data-by-mask/m-p/317797#M4476 HosamEl-Sharkawi 2011-08-02T07:46:51Z