Quality Assurance

Up-to-date orthophotos form a very suitable means to compare the datasets of digital Landscape Models (DLM) with reality. Of course, such a verification can be performed only for those objects and attributes recognizable in the image data. Since it is rather complex, BKG does not perform this verification on an area-wide level for the whole country, but for selected areas only, which means in the form of random samples. Comparison of reality with model is done at an interactive workstation, where the orthophoto is backed with the data of the ATKIS® basic DLM.

Automation of this quality assurance of the ATKIS® basic DLM constitutes one of the goals of a scientific-technical cooperative project between BKG and the University of Hannover. A partial project of this initiative deals with the development of an automized procedure for quality assurance of the ATKIS® basic DLM through photogrammetric means within the frame of the more comprehensive overall concept of a "Wissensbasierter Photogrammetrisch-Kartographischer Arbeitsplatz" (WiPKA) (Knowledge-Based Photogrammetric-Cartographic Workstation).

Moreover, the objective of a prototypical introduction of knowledge-based techniques into production processes of BKG is pursued. Knowledge-based methods allow modelling of hierarchical knowledge about objects in the computer and its use for the recognition of objects in the image. The workstation has been conceived as a partly automated system with which interactive and automatic components complement each other to an efficient sequence of operations. In this context, the portion of automized working steps shall be gradually increased in line with the progress of science and technology. Operator interventions are allowed for in each case in which such interventions contribute decisively to an increase of the efficiency and reliability of the quality assurance of ATKIS®. In a first stage, automatic modules are developed for objects with high topicality requirements, as e.g. roads and settlements.

The images show application examples with which the need for updating of the ATKIS® basic DLM was determined automatically.

Verification of built-up areas: Orthophoto and ATKIS basic DLM

Verification of built-up areas: Orthophoto and ATKIS objects

Verification of roads: Orthophoto and ATKIS basic DLM