Digital Orthophotos (DOP)
Production of Orthophotos
The original is an aerial photograph showing an image of the earth’s surface with a central perspective.
The central projection contains geometrical displacements caused by the tilting of the camera (i.e. when the airplane was swaying when taking the photo) and terrain relief. Therefore it does not have a uniform scale and does not allow to measure true distances.
Prior to the use of an aerial photo for measuring purposes like a map or for integration into a Geographic Information System, it is necessary to correct it geometrically and to establish a reference to a coordinate system. A digital terrain model has to be added and identical control points on the aerial photo and on the reference surface have to be identified.
Such a corrected and geo-referenced aerial photograph is called orthophoto.
There is a great number of possible applications for orthophotos like
- Town and village planning,
- Ecological, pedological, agricultural, geographical or archaeological studies,
- Hydro-engineering work,
- Identification of coastal changes,
- Detection of contaminated land,
- Historical comparisons,
- Preservation of evidence,
- Identification of sealed surfaces,
- Visualization of planned buildings and commercial sites,
- Monitoring of regulations for the protection of trees.
Digital orthophotos for Germany
Due to an administrative agreement, the Federal Agency for Cartography and Geodesy manages the nationwide, state-overlapping distribution of the Digital Orthophotos from the survey institutions in the federal states.
Nevertheless this rule does not affect the direct data distribution option by the federal state survey institutions. And it remains the customer’s decision where to get the data.
Offer and data description
The inhomogeneous datasets contain the Digital Orthophotos (DOP) for Germany as geo-referenced and differentially corrected aerial photos delivered by the survey administrations of the federal states.
The distributed units are referenced on tiles with 2 km x 2 km size. The ground resolution of the orthophotos is 40 cm or 20 cm, depending from the tiles.
Georeferencing in the reference systems of the German national survey is also depending from the tiles: Gauss-Krueger in the stripes or UTM in the respective zone.
The orthophotos are available in a colour version with 24 bit colour depth in the uncompressed TIFF format.
The enormous data volume of the Digital Orthophotos is one of the reasons why we suggest to use our online service where the image data are available via standardized exchange procedures.
It goes without saying that it is also possible to contact our Dienstleistungszentrum and place an order directly with our service staff. There you will also find more information concerning data specifications and questions of charges and licenses, if needed.