Efficient Calculation of Quantities from 3D Geometry in IFC Models

Paper in proceeding, 2026

Accurate quantity take-off is essential for cost estimation, planning, and resource efficiency in construction, as well as for Life Cycle Assessment (LCA) calculations. While the IFC standard theoretically supports quantity data exchange in open BIM workflows, in practice, IFC models often lack reliable quantity property sets—even when the 3D geometry is accurate and complete. To address this, various tools offer geometry-based quantity calculations, but they typically lack transparency, extensibility, or support for complex quantity types. Moreover, the academic literature rarely addresses this challenge from an algorithmic or computational geometry perspective, especially when working directly with non-parametric 3D representations such as indexed triangular meshes. This paper presents a set of methods for calculating construction-relevant quantities directly from 3D mesh geometry found in IFC files. These include net and gross volumes, areas, perimeters, oriented bounds, and projections for both singular and aggregated objects. We provide detailed technical descriptions of our approaches and evaluate them on real-world IFC models in terms of accuracy and performance.