"not_" process not working as expected

[Pratichhya]

A user ran into this issue, where the user is trying to invert the binary mask using ~/ not_ process. However, this is causing unexpected behaviour, with the values being cast to float32 and falling within the range -1, -2.

https://forum.dataspace.copernicus.eu/t/invert-not-of-a-pixel-mask/5323

Reproducible code:

cube_s2 = connection.load_collection(
    "SENTINEL2_L2A",
    spatial_extent = pellworm,
    temporal_extent = t,
    bands = ["B02", "B04", "B08", "SCL"]
)

cube_s2_ndvi = cube_s2.ndvi(nir = "B08", red = "B04")

critereon_1 = cube_s2_ndvi > 0.1
critereon_2 = cube_s2_ndvi < 0.3
combined = (critereon_1 & critereon_2)
inverted = ~combined

cube_s2_ndvi_masked = cube_s2.mask(inverted)

also tried applying not_ through lambda that gives same behaviour as above:

combined = (cube_s2_ndvi > 0.1) & (cube_s2_ndvi < 0.3)
inverted = combined.apply(lambda x: not_(x))

A workaround case could be:

1. inverted = 1-combined
2. inverted = combined == 0

where 1 gives the mask in float32 but within the range 0, 1 and the second one gives the mask in unit8 in the range of 0,1 as well.

I assume this is a bug and needs fixing or clarification in the documentation since the current documentation suggests that the not_ process: Inverts a single boolean so that true gets false and false gets true.

[soxofaan]

This might be a client issue actually:

combined = (critereon_1 & critereon_2)

the & here is translated to a merge_cubes operation with overlap resolver, which is not exactly intended I guess

related tickets:

• Better handling of "cube math" like cube1 / cube2 openeo-python-client#748
• Prevent "band math" like attempts with filter_bands openeo-python-client#239

as a quick-fix: can you try this trick instead:

cube_s2_ndvi = cube_s2.ndvi(nir = "B08", red = "B04", target_band="bands").band("ndvi")