But what can I do about it? I've created a mask shapefile that encompasses all my files but it hasn't helped - I'm not clear on what the mask does. Can I somehow clear a cache so it's recreated.
It does always fail on the same one, but that's not the only one that fails. I thought it might be a problem with cell size but files that have smaller and larger cells have passed through ok. Files that include nulls have also passed ok.
This is the full script - and then the botton 4 lines repeat some 500 times with different inputs and outputs. The point of the script is to look for differences in elevation in adjacent tiles - each tile has a 1 row or column of pixel overlaps with its neighbour.
import arcpy
import os
from arcpy import env
arcpy.CheckOutExtension("Spatial")
from arcpy.sa import *
env.workspace = "c:/myfiles"
arcpy.env.mask = "c:/maskpoly.shp"
inRast = "E000_N00.tif"
inRast2 = "E000_N01.tif"
outRast = Raster(inRast) - Raster(inRast2)
outRast.save = "c:/E000_N00a.tif"