photogrammetry

Photogrammetry can be defined as a measurement technology by which three-dimensional coordinates of points on an object are determined by taking measurements in two or more photographic images that are taken from different positions. Normally in aerial photography this is a block of imagery covering a coherent area.

At Aerodata the process starts with either the full digital images (UltraCam) or by digital photogrammetric scanning of the analogue images.

The digital imagery can then be used for aerial trangulation, DSM/DTM generation and the production of digital orthophotos.
Photogrammetry is used in different fields like topographic mapping, architecture, engineering projects, film and gaming industry.

scanning

Scanning of analogue aerial imagery on our Leica DSW 500 photogrammetric scanner can be executed at different resolutions from 12,5 micron upwards. Image dodging can be performed to compensate for irregular lighting conditions in the images.

aerial triangulation

Aerial triangulation (AT) and block adjustment is the photogrammetric process in which all individual images of a project area are linked together and geo-referenced to the local coordinate system. Aerodata uses the latest versions of specialised software packages such as SocetSet, BINGO and ORIMA.

DSM / DTM generation

By automatic correlation of digital (or digitised) images a Digital Surface Model (DSM) can be calculated. This product describes the height of the earth’s surface, the terrain itself and everything that is on it. By means of filtering and interactive editing of the database the Digital Terrain Model (DTM) can be derived. This is a model of the ground surface.
Elevation models (DSM or DTM) are used in orthophoto production or directly in GIS-applications.
Aerodata uses the latest versions of specialised DTM generation and editing software from INPHO, Match-T and DTMaster.

digital orthophoto production

An orthophoto is an aerial image that is corrected for differences in scale due to the terrain height.
Orthophotos come in two variations:
 

A ground orthophoto is an orthophoto whereby building lean is not taken into account. This is the “basic” version of an orthophoto.

A true orthophoto is a more “advanced” version whereby building height and lean is taken into account and corrected. This means that areas directly around buildings, no matter how tall, can be viewed without any obstruction. True orthophotos can be useful in built-up areas for an accurate fit with maps of building outlines.

Both variations are included in Aerodata’s range of services.

Following this process is general and local colour compensation, which can be fully adapted to the wishes of the customer, to ensure a homogenous end product and mosaicking to combine all orthophotos to produce a seamless orthophoto mosaic.

Orthophoto mosaics are widely used as a reference or background for production of new topographic or thematic maps and GIS-analysis. They are also used for verification and updating of existing spatial data, for spatial planning and land use management.

Aerodata uses the latest versions of specialised orthophoto production and mosaicking software from PCI Geomatics and INPHO.