Radiative heat transfer or light transport are primarily governed by geometric view factors between surface elements. For general surfaces, calculating accurate geometric view factors requires solving integrals via quadrature methods. For complex scenes with many objects and obstacles such calculations are compute-intensive, preventing real-time simulations. The progressive approach detailed here takes as input objects represented by surface triangle meshes and generates as output a dense square matrix of geometric view factors whose accuracy improves over time. The technical parameters of the approaches explained in this paper (hybrid triangle-based and point-based quadratures, tree-based data structure, segment-based probing and prediction) are selected to best trade accuracy for time.