This is a third-order trend-surface model.

How could I interpreted this trend-surface regression model, like the relationship between elevation and distance and x,y coordinate?

I generate formula for polygonial trend-surface model by select sample points in my study area, and the distance to rive is covariable. So, this is a third order trend-surface regression model. How can I interpret this third order trend-surface regression model.

ELEVATION ~ DIST + I(X^1 * Y^0) + I(X^0 * Y^1) + I(X^2 * Y^0) + I(X^1 * Y^1) + I(X^0 * Y^2) + I(X^3 * Y^0) + I(X^2 * Y^1) + I(X^1 * Y^2) + I(X^0 * Y^3)