As urban environments become increasingly vertical, Land Administration Systems (LAS) must support complex 3D spatial representations. While Building Information Models (BIM) offer such capabilities, they are not always available. This paper investigates an alternative approach using point clouds for 3D LAS, focusing on the integration of scanned cadastral floor plans and airborne LiDAR from the Actueel Hoogtebestand Nederland (AHN). We present a semi-automated pipeline that extracts floorplan geometries, segments and enhances AHN data, and synthesizes room-level point clouds. Results from a case study in Rotterdam demonstrate the potential of this approach in the absence of BIM, supporting legal space definition and public visualization. However, challenges such as misalignment due to occlusion in AHN data and inconsistent quality in older floor plan drawings affect the accuracy and automation of the process. The synthetic point clouds include room-level attributes, enabling a seamless integration with AHN, offering a representation of real-world features such as building facades, walls, and fences, which often delineate cadastral boundaries.