Dear overbeek6,
thank you for your feature request! Indeed this would be a great addition to our tool and it ranks quite high on our to-do list.
But I don’t want to leave you without a potential solution for your problem until we implemented it in our software. You can use the Advanced Layer Visualization to find out the threshold value you need which masks out the soil from the vegetation.
Now you can use this in the custom index calculator to create an custom NDVI which masks out all values under that threshold and you end up with a layer which just represents your crops.
And if you want to create more advanced zonation’s you can have a look at this video:
But our aim is to have all those steps represented in a clean and meaningful way in Pix4Dfields down the road.
Thank you very much for your feedback!