Zonal Stats not giving correct maximum value

Discussion created by mlborino on Oct 1, 2010
Latest reply on Oct 4, 2010 by erice-esristaff
I am using ArcMap (ArcInfo license) 9.3.1 on Windows XP. I have a problem where Zonal Statistics is not giving me the actual maximum value of my DEM within the extent of my polygon shapefile. Zonal Stats says maximum is 560.945, but when I did a check, there are pixels completely within the polygon file with larger values (561.162). All files are in the same projection. Can anyone explain why this is happening or have any other ideas? This is only one polygon that I happened to notice the error. I'd hate to have to check it for them all!

Another question along these lines- how are partial pixels within the polygon extent treated?

Thank you,