A method can include receiving a node-based mesh that represents a geologic environment and a structural feature in the geologic environment; defining a node-based parameter space for structural uncertainty of nodes that represent the structural feature in the geologic environment; defining a hull with respect to nodes of a portion of the mesh where the hull encompasses at least a portion of nodes that represent the structural feature; for a system of equations, imposing boundary conditions on the nodes of the hull and on the at least a portion of the nodes that represent the structural feature; solving the system of equations for a displacement field; and generating a structural uncertainty realization of the node-based mesh based at least in part on the displacement field.