| | At the same time as the elevation data, digital image data is recorded with the aid of a line scanner in the four spectral channels:
- Blue 450 nm - 490 nm
- Green 500 nm - 580 nm
- Red 580 nm - 660 nm
- Near infrared 770 nm - 890 nm
The image data is initially available in uncorrected form in individual strips, and is rectified and georeferenced with the aid of the elevation model. For this purpose, the image data is blended with the elevation model from the laserscanner data recorded synchronously with the image data. A presentation in true ortho image projection is achieved by the use of the DSM digital surface model. Unlike conventional ortho images, vertical walls of buildings are correctly projected, roofs and cars are not offset. The single strips are then radiometrically balanced by way of statistical brightness and contrast adjustments and are combined to form a homogeneous image mosaic.
The quality of the true ortho images is particularly dependent on the outside conditions (cloud, lighting) and is not subject to any control by TopoSys.
The image data is supplied as standard in georeferenced form, in three channels, as a true color (RGB) image and as a color infrared (CIR) image in true ortho projection. Other combination options or formats are available on request. |
