Hi @stefaan.lippens, you are right. Basically the main difference is that in the first version, the areas that are at no data of the second have value 129 instead of nan.
Anyway, both results are wrong, apparently when doing the comparison step, the no data values get messed up.
I think the problem is that the VITO backend does not preserve nan-ness in comparisons: like ndsi > 0.4: pixels above 0.4 get value 1 and all other values (below 0.4, and nan) get value 0. This is probably because the data type in the implementation is just binary and there is no room for a third value like nan.
Ok, but how should a normal user get to know about these details? It’s a bit frustrating for an advanced user like me already, I can imagine how it would be for a newbie.
I guess that if a process is implemented in a different way than the specs should be documented somewhere and probably also the exposed process definitions should be aligned: https://openeo.vito.be/openeo/1.1/processes