ERROR 999998: Unexpected Error raster algebra
Well I was going to try it on the Surface Book...
I suspect it is just the superiorness of the machines... 
If it works on one machine and not another then it has something to do with the environments on that machine.
*.tif is the correct extension as well.
I will still have a look
I just ran the code with a small change and it ran without problems.
The only thing I changed was the setting of the workspace (your line 36) and I changed it to point at a fgdb. This was enough for it to finish correctly:
C:\GeoNet\UAV2017
Field8_90ft_08012017
Results folder successfully created
C:\GeoNet\UAV2017\Results\Field8_90ft_08012017_ExGr.tif
Excess Green successfully calculated
Pyramids and Statistics successful
Duration: 0:10:39.098000 Resulting image:
Before the change it created tmp results in the workspace for the 3 band calculations and those rasters may cause problems due to the length of the names and the less efficient data storage that TIF uses, hence the memory problems I guess.
Dear Xander and Dan,
I made a small change on the code an it is working now. Maybe you guys can help me understand why. I just basically comment out lines 31, 32, and 33. I ran the code using a shorter name version (without the base) and a long one (with the base as part of the name), and both of them worked. The only other change was line 36, where the env.workspace is set to path (line 13). You can see the results bellow and the raster image in ArcGIS.
import arcpy, string, os, errno
from arcpy import env
from arcpy.sa import*
from datetime import datetime
arcpy.CheckOutExtension("spatial")
arcpy.env.overwriteOutput = True
start_time = datetime.now()
imagery = r'E:\UAV2017\PythonField8ExGr\Field8_90ft_08012017.tif'
#Get path information to create Results folder, where NDVI and NDRE will be saved
path = os.path.dirname(imagery)
print path
base1 = os.path.basename(imagery)
base = os.path.splitext(base1)[0]
print base
folder = "Results2"
Results2 = os.path.join(path,folder)
if not os.path.exists(Results2):
os.makedirs(Results2)
print "Results folder successfully created"
#Saving name for Excess Green mosaic - using basename from the original imagery
exgr_filename = os.path.join(Results, base + "_ExGr.tif")
ngreen_filename = os.path.join(Results, base + "Ngreen.tif")
nred_filename = os.path.join(Results, base + "Nred.tif")
nblue_filename = os.path.join(Results, base + "Nblue.tif")
#Set workspace to multiband raster, then list rasters to get band names
##arcpy.env.workspace = imagery
##bands = [Raster(os.path.join(imagery, b)) for b in arcpy.ListRasters()]
##print bands
#Set workspace to the location were the results will be saved
arcpy.env.workspace = path
#Excess Green calculation - (2*Ngreen-Nred-Nblue)
Ngreen = (Float(bands[1])) / (Float(bands[0]) + bands[1] + bands[2])
Ngreen.save(ngreen_filename)
print "Ngreen succesfully calculated"
Nred = (Float(bands[0])) / (Float(bands[0]) + bands[1] + bands[2])
Nred.save(nred_filename)
print "Nred succesfully calculated"
Nblue = (Float(bands[2])) / (Float(bands[0]) + bands[1] + bands[2])
Nblue.save(nblue_filename)
print "Nblue succesfully calculated"
exgr = ((2 * Ngreen) - Nred - Nblue)
exgr.save(exgr_filename)
print "Excess Green successfully calculated"
#Build pyramids and calculate statistics for each raster in env.worspace folder
arcpy.BuildPyramids_management(exgr_filename)
arcpy.CalculateStatistics_management(exgr_filename)
print "Pyramids and Statistics successful"
end_time = datetime.now()
print('Duration: {}'.format(end_time - start_time))E:\UAV2017\PythonField8ExGr
Field8_90ft_08012017
Results folder successfully created
Ngreen succesfully calculated
Nred succesfully calculated
Nblue succesfully calculated
Excess Green successfully calculated
Pyramids and Statistics successful
Duration: 0:02:50.354000
