Abstract: A portable dimensional reference (PDR) that is transportable to a tower site and deployable on site at ground level near a tower. The PDR includes a pair of target pads and multiple connecting segments, which may be attached end-to-end between the target pads. The target pads are marked with respective targets that enable photogrammetry software to identify the targets, their locations, and the distance between them with high precision, enabling the software to apply the known distance as a scale constraint for accurately scaling dimensions of imaged components of the tower.