The camera calibration and verification laboratory (CAVE Lab) is located in a separated area of the integration room. Its walls and ceilings are blackened to supress stray light. The measuring equipment enables us to determine the optical properties of the camera systems of Flying Laptop and of the unmanned aerial vehicle Stuttgarter Adler and to calibrate them.

The calibration of cameras can be classified into three domains:

• radiometric calibration,
• spectral calibration,
• geometric calibration.

Radiometric calibration is used to measure the sensitivity of every pixel of the camera sensor. So it is possible to determine the physical value of a signal by using the digital value measured by the camera. Therefore, we use a light source with known radiance and spectral distribution, a so called integrating sphere, with 500 mm diameter.

The intention of spectral calibration is, to investigate the sensor characteristics to light in different wavelengths. This is important, because CCD-Sensors, as well as the optics have wavelength-dependent properties. To achieve this, the measurement setup consists of a Quartz Tungsten Halogen lamp as light source, a monochromator to select a narrow band of wavelengths from the light source spectrum, as well as a lens setup to focus the light.

The primary purpose of geometric calibration is to deterine the inner orientation of the cameras and thus the exact position of every pixel in space. It is used to characterize and correct the distortions generated by the optics. This can be achieved by analyzing images of test patterns from different angles and distances.