An Orthophomap can be defined as a map made by assembling a number of orthophographs into a single, composite picture. Orthophotomaps can be classified into two groups, namely;

"Digital orthophoto: A raster photographic image that is combined with differential rectification to remove image displacements caused by camera tilt and terrain relief."

A digital orthophoto is simply a photographic map that can be used to measure true distances. It is an accurate representation of the earth's surface. To create a digital orthophoto, several key input files are necessary: aerial photos with a high-percentage overlap, scanned imagery, aerotriangulation (A.T.) results, and a digital elevation model (DEM). Scanned imagery can be obtained from scanning aerial photo diapositives or negatives on an image-quality scanner. The A.T. results include a camera calibration report and the ground control. At a minimum, the DEM can be a regularly spaced grid of masspoints, each containing an x, y, and z value. A more robust digital terrain model (DTM) can also be used because it includes strategically placed masspoints, dense breaklines, and ridgelines.