Developing three dimensional models of infrastructure and construction in progress can be useful for designing modifications, for tracking work completed, and for facilitating advanced equipment control and safety functions. An emerging 3D modeling method involves scanning scenes with laser ranging devices. The resulting dense or sparse point clouds are converted to primitive geometric objects. Merging those objects is useful for visualization and advanced manipulation. Factors that influence this merging process are identified here. Heuristics are proposed for automated merging, and initial results presented.