Hi all,

I would like to do the pca (principal component analysis) of my Sentinel-2 
multiband image composed of nine 20m-L2A rasters. I tried with the 
otbcli_DimensionalityReduction module (the method parameter was set to 
“pca”), but the statistics of the output image is not as I expected. 
Namely, all the bands of the output image has the standard deviation equal 
to 1.

Generally, I expected that the output pca bands have standard deviations 
different from 1. This would then allow me to select the most significant 
bands according to the variance loss criteria.

Is this a bug of the DimensionalityReduction –pca algorithm, or there is 
maybe another way in orfeo toolbox to get the pca bands without std 
normalized to 1?

Thank you in advance for your time and the help!

Cheers,
Kimi


PS.

I am using orfeo 6.4.0 from the command line, and there is my code:

>>otbcli_DimensionalityReduction -in test2.tif -out pca_norOFF.tif -method 
pca -normalize 0

>>otbcli_ComputeImagesStatistics -il pca_norOFF.tif

and this is the statistics for 9 bands from the pca output image:

Mean: 2.14067, -1.29191, 0.554654, 0.996805, -0.267422, 0.423317, 0.285117, 
0.281447, -0.183358 Standard Deviation: [1, 1, 1, 1, 1, 1, 1, 1, 1]

My input multiband image can be downloaded from here:

https://files.fm/u/2vh7aqvu

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