Sensor reference creation
With the current implementation, the first image found is used as 'reference image'
In case of sensor provided as monoband images, the first band is used.
In case of multiband image, the whole image is used.
The reference image is used to have extent, projection and resolution information and the data are not used.
In case of userfeat (the sensor) the first pattern provided is used. And it is used to create a fake masks time series.
If this image is big (>40gb) this can lead to memory errors.
A solution could be to keep only one band as reference after the Warp