Description
The Hamburg city area has been recorded with aerial photographs since 1920. The aerial photographs document the city structure and its changes in an impressive way and are an indispensable means of data acquisition. To take a look at Hamburg from above, you don't have to go into the air or get someone on the roof. It’s also easier — with the help of images taken from the plane. Colored aerial images are unusual and impressive image documents and give an unmistakable impression of the face and beauty of our city. However, they not only satisfy our aesthetic sense, but also offer a wide range of interesting applications to professionals.
Digital cameras are now almost exclusively used for aerial photography. The recording technologies available on the market differ in area sensors and line scanners. The most well-known digital camera models are DMC, UltraCam, ADS40 or the HRSC.
Currently, Hamburg’s image flight planning usually provides for a visual flight per year for vertical images: for this purpose, the entire area of the Free and Hanseatic City of Hamburg (FHH) will be flown in spring (before the certification) for the purpose of photogrammetric aerial analysis and orthophoto calculation. In addition, an aerial aerial flight for the entire area of the FHH with the aim of orthophoto production takes place at the rhythm of 3 to 4 years during the summer months (with full certification). Projects of overarching importance sometimes also require special aircraft, which the LGV supervises, commissions and invoices in coordination with its customers.
Since, on the one hand, airflies and subsequent data processing are extremely time-consuming and cost-intensive and on the other hand want a large number of different customers derived aerial data without having to deal intensively with camera technologies, flight times, prices or image flight companies, LGV was determined for Hamburg’s administration as a central purchasing body for photogrammetric services (MittVw 10/99, p. 230 ff) especially against the background of minimising costs and ensuring quality.
Analog aerial images (historical aerial images) no longer needed for use by LGV are submitted to the State Archives and are particularly popular for historical research, e.g. for contaminated sites. Contact for this is the State Archives in the Kattunbleiche 19. For more information, please refer to the following link: http://www.hamburg.de/staatsarchiv/
The purpose of aerial photographs can be roughly classified into the following categories:
— Stereophotogrammetric aerial image evaluations (vector data)
— Orthophoto calculations (grid data)
— Aerial maps (hybrid data)
— Inclined aerial images (photos of concise areas of Hamburg)
Standard products, such as orthophotos, aerial maps and oblique aerial images, are distributed by LGV in aerial image distribution or on the Internet on various CDs and as printed maps. For special requirements and aerial image evaluations, the department “3D and Remote Sensing” provides advice and assistance to every interested party.
Aerial image evaluation:
With the help of digital stereo workstations, the air-visible topography can be evaluated three-dimensionally in accordance with the accuracy requirements and transmitted to CAD programs. Photogrammetric accuracy depends (among others) on altitude and ground resolution. The main area of application of photogrammetric evaluations in the LGV is the continuation of the ALKIS® property map and the 3D city model.
The following image material is currently available for the aerial image evaluation:
— complete area of the FHH: Image flight time spring 2018, color, 5 cm ground resolution.
The high-resolution aerial images are classified as relevant to data protection and are not passed on to third parties.
However, there is much more potential in stereophotogrammetry. One example is sealing plans that the LGV can create for Grand Leaders. Consumers who purchase more than 5000 cubic metres of fresh water per land per year save cash in accordance with Section 15a of the Sielabgabengesetz by submitting a refund application. When calculating the sielbe usage fee, the part attributable to the proportion of rainwater can be reduced. For this purpose, it is necessary to determine the size of the building surfaces, the paved surfaces, the softly fixed and green areas. In addition, an inventory plan with the different types of areas marked in colour must be submitted. The regional company Geoinformation and Surveying offers its customers to provide the corresponding tabular compilations and plans. The data is obtained by evaluating the latest aerial images and supplemented and classified by a local field comparison.
Other applications of stereophotogrammetry include, for example, the creation of existing, green space, tree and roof landscape plans. But also height evaluations, from individual terrain points or objects can be determined cost-effectively. The automated extraction of surface models is also conceivable by means of correlation methods.
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Tags
- cir-bild
- orthophotomosaik
- luftaufnahme
- luftbildarchiv
- orthophotos
- bildmaßstab
- cir
- digitale-ortophotos
- farbinfrarot-orthophoto
- stereophotogrammetrie
- stereobetrachtung
- dop
- envi
- bodenauflösung