Troubleshooting: Known limitations¶

Failure of intermediate writing¶

When chaining applications in-memory, there may be some problems when writing intermediate results, depending on the order the writings are requested. Some examples can be found below:

Example of failures involving slicing¶

For some applications (non-exhaustive know list: OpticalCalibration, DynamicConvert, BandMath), we can face unexpected failures when using channels slicing

import pyotb

inp = pyotb.DynamicConvert('raster.tif')
one_band = inp[:, :, 1]

# this works
one_band.write('one_band.tif')

# this works
one_band.write('one_band.tif')
inp.write('stretched.tif')

# this does not work
inp.write('stretched.tif')
one_band.write('one_band.tif')  # Failure here

When writing is triggered right after the application declaration, no problem occurs:

import pyotb

inp = pyotb.DynamicConvert('raster.tif')
inp.write('stretched.tif')

one_band = inp[:, :, 1]
one_band.write('one_band.tif')  # no failure

Also, when using only spatial slicing, no issue has been reported:

import pyotb

inp = pyotb.DynamicConvert('raster.tif')
one_band = inp[:100, :100, :]

# this works 
inp.write('stretched.tif')
one_band.write('one_band.tif')

Example of failures involving arithmetic operation¶

One can meet errors when using arithmetic operations at the end of a pipeline when DynamicConvert, BandMath or OpticalCalibration is involved:

import pyotb

inp = pyotb.DynamicConvert('raster.tif')
inp_new = pyotb.ManageNoData(inp, mode='changevalue')
absolute = abs(inp)

# this does not work 
inp.write('one_band.tif')
inp_new.write('one_band_nodata.tif')  # Failure here
absolute.write('absolute.tif')  # Failure here

When writing only the final result, i.e. the end of the pipeline (absolute.write('absolute.tif')), there is no problem.