Stack rioxarray DataArrays for output to GeoTIFF

Question

I am trying to read a GeoTIFF, perform calculations (radiometric correction) on all bands, and then output back to GeoTIFF. Most of the code I have works fine, up until trying to output.

import os
import rioxarray as rxr
import numpy as np
import pandas as pd

wv3tif = rxr.open_rasterio(os.path.join(os.getcwd(), "WV3 MUL GDA2020UTM55.tif"))

sensorvals = pd.read_excel(os.path.join("WV3_band_details.xlsx"))

L_bands = []
for band in range(len(sensorvals['Band no.'])):
    L = np.add(np.multiply(wv3tif[band], (sensorvals['GAIN'][band] * sensorvals['abscalfactor'][band] / sensorvals['effectivebandwidth'][band])), sensorvals['OFFSET'][band])
    L_bands.append(L)
    
L_bands.rio.to_raster("WV3 MUL GDA2020UTM55 TOA radiance.tif")

The last line throws an error 'numpy.ndarray' object has no attribute 'rio' because the data is no longer an xarray.core.dataarray.DataArray object. I have tried to vstack but since that's a numpy routine it only returns an ndarray without the necessary output methods.

How do I stack the list of bands for output with rioxarray, including outputting with original CRS and coords?

Answer 1

As per this post the correct method seems to be

y = wv3tif['y'].values
x = wv3tif['x'].values
band_vals = wv3tif['band'].values

L_bands = []
for band in range(len(sensorvals['Band no.'])):
    L_bands.append(np.add(np.multiply(wv3tif[band].data, (sensorvals['GAIN'][band] * sensorvals['abscalfactor'][band] / sensorvals['effectivebandwidth'][band])), sensorvals['OFFSET'][band]))

L_output = xa.DataArray(L_bands, coords={'y':y, 'x':x, 'band':band_vals}, dims=['band', 'y', 'x'])

L_output.rio.to_raster("WV3 MUL GDA2020UTM55 TOA radiance.tif")

This now correctly writes the GeoTIFF with the modified pixel values