Landscape sightline analysis and height control in heritage areas based on Grasshopper: a case study of Coloane Island, Macau

Rapid urban development in high-density coastal mountainous cities can threaten the visual integrity of landmark cultural heritage, while existing conservation approaches often lack quantitative control of the surrounding built form. This study investigates the landscape sightlines of the Mazu statue in the Mazu Cultural Village on Coloane Island, Macau, and develops a parametric framework for integrating heritage visibility with building height control. A Rhino–Grasshopper model was established to assess visibility across a 2000 m study area using grid-based viewpoints, hierarchical concentric zones, and a sightline envelope method. The results reveal clear spatial differentiation in visibility, with 1000 m identified as the core stable visibility boundary and 1000–1500 m as the critical transition zone. A three-tier protection system of 500 m, 1000 m, and 2000 m was established, and parcel-level building height thresholds were derived according to spatially varying visual sensitivity. The findings indicate that some existing height controls are insufficient in mid-field areas, whereas greater development flexibility may be feasible in visually screened far-field areas. The proposed framework provides a quantitative and transferable basis for refining heritage visual protection and coordinating landscape conservation with urban development in complex coastal environments.