Photogrammetry uses overlapping images taken from different angles to reconstruct 3D models or maps of landscapes, buildings, or objects. Images are processed with the use of specialized computer software to create detailed orthophotos, elevation models, contour maps and 3D models. Engineers and Project Management firms use these maps to perform measurements of area, segmented line distances, slope angles, utility right-of-ray boundaries and many other functions. Photogrammetry is widely used in topographic mapping, urban planning and infrastructure and disaster response.