KEYWORDS: Cameras, Sensors, Navigation systems, Microsoft Foundation Class Library, Remote sensing, Sensing systems, RGB color model, Global Positioning System, Computer science, Aerospace engineering
Aerial line cameras allow the fast acquisition of high-resolution images at low costs. Unfortunately the measurement
of the camera's orientation with the necessary rate and precision is related with large effort, unless extensive
camera stabilization is used. But also stabilization implicates high costs, weight, and power consumption. This
contribution shows that it is possible to completely derive the absolute exterior orientation of an unstabilized line
camera from its images and global position measurements. The presented approach is based on previous work
on the determination of the relative orientation of subsequent lines using optical information from the remote
sensing system. The relative orientation is used to pre-correct the line images, in which homologous points can
reliably be determined using the SURF operator. Together with the position measurements these points are
used to determine the absolute orientation from the relative orientations via bundle adjustment of a block of
overlapping line images. The approach was tested at a flight with the DLR's RGB three-line camera MFC. To
evaluate the precision of the resulting orientation the measurements of a high-end navigation system and ground
control points are used.
KEYWORDS: Sensors, RGB color model, Data modeling, Cameras, Imaging systems, 3D modeling, Systems modeling, Data acquisition, Data fusion, Data processing
New stereo push broom camera systems have been developed at German Aerospace Centre (DLR). The new small
multispectral systems (Multi Functional Camerahead - MFC, Advanced Multispectral Scanner - AMS) are light weight,
compact and display three or five RGB stereo lines of 8000, 10 000 or 14 000 pixels, which are used for stereo
processing and the generation of Digital Surface Models (DSM) and near True Orthoimage Mosaics (TOM).
Simultaneous acquisition of different types of MFC-cameras for infrared and RGB data has been successfully tested. All
spectral channels record the image data in full resolution, pan-sharpening is not necessary.
Analogue to the line scanner data an automatic processing chain for UltraCamD and UltraCamX exists.
The different systems have been flown for different types of applications; main fields of interest among others are
environmental applications (flooding simulations, monitoring tasks, classification) and 3D-modelling (e.g. city
mapping). From the DSM and TOM data Digital Terrain Models (DTM) and 3D city models are derived. Textures for
the facades are taken from oblique orthoimages, which are created from the same input data as the TOM and the DOM.
The resulting models are characterised by high geometric accuracy and the perfect fit of image data and DSM.
The DLR is permanently developing and testing a wide range of sensor types and imaging platforms for terrestrial and
space applications. The MFC-sensors have been flown in combination with laser systems and imaging spectrometers and
special data fusion products have been developed. These products include hyperspectral orthoimages and 3D hyperspectral data.
To generate ortho photos and terrain models from airborne and spaceborne linescanner images, various complex
radiometric and geometric corrections have to be applied to the raw images. In this contribution a software-concept is
presented, that allows the configuration and application of a modular and expandable chain of such corrections through
an interactive graphical user interface. The effect of any changed correction parameter is visualized immediately in
zoomable preview-windows. Different correction-steps are illustrated with respect to the generation of terrain models
with Semi-Global Matching (SGM), including radiometric sensor and atmosphere correction, as well as sensor boresightalignment
calculation and aerotriangulation.
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