Problem Statement: The 2D cadastre faces ambiguities and legal disputes in registering 3D properties, such as apartments, tunnels, and vertical easements. In Iran, the Comprehensive Cadastre Act (2014) does not address the third dimension, and this legal gap is the main obstacle to developing a 3D cadastre.

Methodology: This article adopts a comparative approach, examining the legal and registration systems of three leading jurisdictions – Queensland (Australia), Victoria (Australia), and the Netherlands – across four aspects: (1) legal definition of 3D objects; (2) types of registrable rights; (3) technical guidelines; and (4) the responsible institution and ongoing developments. These are then compared with the situation in Iran.

Findings: Queensland, with its distinction between “Lot” and “3D Parcel” and its mandatory technical guidelines (CSR and RTDPP), has the most advanced framework. Victoria, with its evolved laws, is moving toward digital standards (ePlan, IFC, CityGML). The Netherlands, based on the principle of unity of land and building ownership, does not accept the registration of independent 3D volumes but uses 3D PDFs in official deeds. In Iran, there is no legal definition of the third dimension, no technical guidelines have been developed, and concepts such as 3D parcel are not defined. Existing activities are mainly focused on design and construction, not on land registration.

Conclusion: Amending the Comprehensive Cadastre Act to include 3D definitions, developing technical guidelines based on ISO 19152, and mandating digital 3D documents are essential prerequisites for moving toward a 3D cadastre in Iran.