# #StackBounty: #machine-learning Are models using satellite image inputs well-posed?

### Bounty: 50

I am using machine learning to create a land use regression model. My inputs are geographic coordinates. These I use to extract 80×80 meter satellite images or maps to feed the model.

Lets take the example of a neural network:

Existence: The solution will always exist for any finite input. It may overflow if the input and/or weights are unreasonable large, but the solution exists in principle.

Unique: The solution will be unique by definition. Of course, the training data may have non-unique outputs for their inputs due to measurement noise, but the resulting model will only produce one output given an input.

Continuity: Hadamards last criterion I am uncertain how to adjust to land use regression. While neural networks are function compositions of continuous functions and thus continuous themselves, the input space is not; The border between various object, like houses and streets, form discontinuities.

Sure, if I deform what’s inside the image continuously, there is no issue, but how can I allow, lets say, a new street continuously enter the image? If I start scanning over a street, and I do it as a function of time, there will be a time $$t_n$$ in which the image $$I(t_n)$$ does not contain the street but after which $$I(t_n +delta)$$ will include the street for all $$delta>0$$ (as long as $$delta$$ is not so large that the street has left on the opposite side of the image). This is a discontinuity that would lead to discontinuous output as well, and thus contradict Hadamards final property.

What is the correct way to think about this if I want it to be well-posed? I mean, I guess I can consider my inputs as a local statistic of sorts while my actual input is the entire globe… But, how would one go about making land-use regression well posed? Or for that sake, any problem where the input is a rectangular subset of Earth as seen from space.

Get this bounty!!!

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