I have a square plane mesh with applied texture (satellite image of an area) and displacement (height map) that gives an overview of a land area with some features like water which I want to remove.

Water is on the Z axis value = 0, it is also of particular color (blueish). I also have a detailed shape polygon that I could cut from the plane so only area of interest is shown.

My question is how would I proceed with removing vertices from the geometry according to their feature (Z-axis value) or texture color (color blueish)?

Alternative approach, how would I cut the plane along given polygon (taken from geojson, not aligned to plane vertex positions)?

I have a square plane mesh with applied texture (satellite image of an area) and displacement (height map) that gives an overview of a land area with some features like water which I want to remove.

Water is on the Z axis value = 0, it is also of particular color (blueish). I also have a detailed shape polygon that I could cut from the plane so only area of interest is shown.

My question is how would I proceed with removing vertices from the geometry according to their feature (Z-axis value) or texture color (color blueish)?

Alternative approach, how would I cut the plane along given polygon (taken from geojson, not aligned to plane vertex positions)?

picture for reference