Definition
An Orthophoto, also known as an orthoimage or orthophotograph, can be defined as an aerial photograph that has been geometrically corrected or "orthorectified" in a way such that the scale is uniform. This correction means the photo has the same lack of distortion as a map. Unlike an uncorrected aerial photograph, an orthophoto can be used to measure true distance, because it is an accurate representation of the Earth's surface, having been adjusted for topographic relief, lens distortion, and camera tilt.
What is Orthophoto?
An Orthophoto is an imagery dataset, produced from aerial photographs by utilizing photogrammetric technology in which relief displacements of features have been removed. Thus, they represent an accurate 2D image of the ground surface, akin to a bird's eye view. Orthophotos provide an accurate visual record of the surface of Earth, preserving natural features and infrastructure in their geographical context.
Orthophotos are commonly utilized in Geographic Information Systems (GIS) as a map accurate background image. They can be utilized in digital form or can be printed to produce a hardcopy output. Furthermore, they can be overlaid and used in combination with other geospatial data layers (e.g., road networks, hydrology) to provides analysts a complete picture of the spatial relationships of geographic features.
FAQs
What are the Key Uses of Orthophotos?
Orthophotos are heavily used in many sectors such as urban planning, agriculture, forestry, environmental studies, and any project requiring geospatial data. They can be used for base mapping, measuring, land use studies, and in creating composite maps overlaying other spatial data.
What is the Difference Between an Orthophoto and a Satellite Image?
Satellite images and orthophotos both provide a view from above, but they are derived from different sources. Satellite images are captured from space, while orthophotos are generally obtained from aircraft. Moreover, orthophotos are corrected for distortions related to camera and flight mechanics and terrain, making them map-accurate.
What is the Process of Creating an Orthophoto?
The process of creating an orthophoto primarily involves the collection of aerial photography, the creation of a digital terrain model (DTM), and the application of the DTM to the aerial photos during the orthorectification process. The orthorectification process corrects the photos based on lens distortions, displacement in images due to terrain, and errors caused by camera angles.
What Software is Used to Create Orthophotos?
The creation of orthophotos is usually performed using specialized software, such as Photogrammetric Software, Ortho Mapping software, and GIS software. Examples include AutoCAD Civil 3D, ArcGIS Pro, Pix4D and others.
