AirSpex 2007

2. Instrumentation



Figure 2.1: Instrumentation setup,A Webcam, B Digital camera, C Spectral imager, D Gyro


The instrumentation on the helicopter flight on the AIRSPEX 2007 campaign consisted of three different tools for producing images.


A low cost portable spectral imager generating images as a function of wavelength was the main instrument for the project. Both the helicopter flight and the Drone made use of the Dronespex with following specifications:


Entrance slit dimension: 4.5 x 0.025 mm
Focal lengths:
L1 (front lens): 12 mm
L2 (collector lens): 42 mm
L3 (camera lens): 25 mm

Wavelength range: 374 - 700 nm
FWHM: 2 nm
sensitivity: 0.00015 lux
Grism: 30 deg Littrow prism and a transmitting holographic grating with 600 grooves/mm

The CCD recording the resulting images is of size 6.837 x 4.9468 mm with #pixels of 795 x 596 and a pixel size of 8.6 um x 8.3 um


Since the target could not be covered by one image but by many images produced in a continuous interval all frames were stored on a digital video recorder creating a spectral movie with a dynamic rage of 8 bites per pixel.


To provide high spatial resolution coverage of the target area and to have evidences for a later classification of the spectral images a digital high-resolution camera ( Nikon D200 SLR, 10 mega pixels) and a webcam (Logitech Webcam for quick snapshots) were mounted next to the spectral imager as shown in figure 2.1.


It is imported to be certain of position and time of the produced frames, therefore the instruments were connected to a GPS. The connection to a Gyro (D in figure 1) corrected the images for plane movements in pitch, roll and yaw direction.




Data processing


For processing the data two programs were used.

The yaPlaySpecX software was used to convert the spectral movies recorded by the digital video recorder to spectral images and the ImageCalculator (created by Karsten Heia) for generating of colour images and for classifying the generated images.