<p>Precise elevation design on an aerially reconstructed terrain can ensure an appropriate structural slope for good driving conditions and dovetail the design with real world. Traditional planners are used to drawing curves for 2D floor design, but there is no mechanism to design a 3D terrain based on editing the cross-section of selected 2D ground curves. Therefore, this work aims to bridge the gap between the intuitive 2D curve-based design practice and precise 3D terrain construction. Since floor planners generally refer to 2D cross-sections for elevations and are more familiar with curve manipulation instead of 3D mesh editing, this work proposes an elevation modeling tool based on editing the 2D cross-section of user-drawn ground-projected curves. The system is designed to align with intuitive 2D curve-based design practices by first letting users draw curves on the ground as 3D-constrained parametric curves. It constructs a ground-projected plane for 2D cross-sectional manipulation to achieve precise altitude control. The system diffuses the parametric elevations to their surroundings and constructs its height field by solving the corresponding differential equation. Finally, remeshing is applied to ensure patch boundaries precisely align with the constrained curves. Thus, our system can address the difficulty and complexity in precise elevation control and boundary alignment of brush-style, feature-based, and NURBS-based knot-tuning methods. Numerical experiments and a usability study of naive users and experts demonstrate our intuitiveness and effectiveness over state-of-the-art methods and verify our ability to mimic traditional 2D curve-based design practice.</p>