Orthophoto generation is the rectification of the distortions in the aerial photographs captured by satellites or image sensors. These distortions are caused due to the systematic sensor or platform-induced aberrations or relief features of the terrain. The geometrical rectification of such distorted images is also known as ortho rectification. This process finds its major use in the Geographic Information System (GIS) industry.

Ortho rectified images have uniform scale which can be used to measure true distances. The orthophoto imagery process gives highly valuable and accurate data representation of the earth's geographic surface. Orthophoto generation of the aerial photography eradicates the effects of topography relief, lens distortion, and sensor tilt from acquired viewpoint.

The orthophoto serves as an accurate map base to obtain precise measurements of objects and other geographical features. These orthophoto maps facilitate the public as well as private sector to plan the inventory infrastructure, land-use projects, environmental conditions, flood plain boundaries for maps, public communications requirements, transportation improvements and other important projects.

Orthophoto maps depict land features using processed and enhanced color photographic images with details in true position. They portray extensive areas of sand, marsh, or flat agricultural areas. These maps give a realistic and natural perspective to an area. Contours may or may not be included in an orthophoto map.

The entire orthophotography generation is divided into two important processes – Ortho Rectification and Mosaicking. While the former eliminates the effects of relief displacement or camera tilt, the latter merges the individual images into a perfectly tailored image database. Factors like resolution of the satellite image/photo, quality of DEM (Digital Elevation Model) and land geography influences the accuracy of an orthphoto.

The Locations where the ground elevation changes abruptly (such as at vertical cliffs, retaining walls, and bridges) hires high accuracy requirements. If such sudden vertical changes are out of reach of the machine used, two separate ortho photographs of similar areas - one depicting the upper level of the terrain and another depicting the lower level of the terrain, are created. Once the two are combined, either by special photographic printing techniques or by removing a portion from one ortho photograph and inserting it into the other, the output image will thus ensure the inclusion of all dimensional and aesthetic specifications.

The aerial photographs are scanned and converted into a raster image format. The collecting points indicate the changes in elevation and the control points indicate the geometric distortions. While the digital terrain model specifies the collecting ground points, the stereo model notifies the control points in the photograph. This image is then rectified and geo referenced using mathematical models of photogrammetry to remove any digital image distortions.

Nowadays, second generation orthophoto is more preferred and used over first generation orthophoto imagery, as this produces high resolution orthophoto with short production schedule in a way cost-effective manner. Some cases require the stitching of several orthophotos to form a composite ortho image file. This calls for highly sophisticated technology to generate such precise dimensions and data in each orthophoto imagery.