Hyperspectral surveys of Ningaloo Marine Park, Western Australia

HyVista Corporation was contracted by AIMS to acquire hyperspectral data over Ningaloo Marine Park in Western Australia. A total of 67 HyMap image strips were acquired, within 11 individual Blocks (A-K), between the 20th of April and the 2nd of May, 2006. The HyMap data products that have been delivered are radiance, reflectance and geocorrected data.The data acquisition was conducted in individual blocks. Each HyMap data block was acquired in one sortie and whenever possible HyVista tried to fly more then one block in one day. Due to survey time restrictions, Block F was acquired on two different days to allow for optimal sun angles. The HyMap survey was planned to cover the water areas to the 20m bathymetry line. Two blocks (G and F) cover it all the way to the 50m line. The survey was also extended to cover the Muiron Islands and the land area past Exmouth town. The area covered total 3400 square kilometers collected at 3.5m pixel size.Derived bathymetry and habitat models.
 The HyMap sensor is an airborne imaging system that is used for earth resources remote sensing. It records a digital image of the earth's sunlit surface underneath the aircraft but unlike standard aerial cameras, the HyMap records images in a large number of wavelengths. In essence, the HyMap is an airborne spectrometer and like spectrometers used in analytical chemistry, it can detect and identify materials by the spectral features contained in the recorded data.The HyMap records an image of the earth's surface by using a rotating scan mirror which allows the image to build line by line as the aircraft flies forward. The reflected sunlight collected by the scan mirror is then dispersed into different wavelengths by four spectrometers in the system. The spectral and image information from the spectrometers is digitized and recorded on tape.The HyMap sensor utilizes four 32-element detector arrays (1 Si, 3 liquid-nitrogen cooled InSb) to provide 126 spectral channels covering the 450nm to 2500nm spectral range over a 512 pixel swath.To minimize distortion induced in the image by aircraft pitch, roll and yaw motions, the HyMap is mounted in a gyro-stabilized platform (Zeiss SM2000). While the platform minimizes the effects of aircraft motion, small image distortions remain. These residual motions are monitored with a 3 axis gyro, 3 axis accelerometer system (IMU-inertial monitoring unit). The system currently used with the HyMap is a Boeing C-MIGITS II.Associated with the actual HyMap optical system is an electronics sub-system which is rack mounted in the aircraft. This electronics sub-system provides the sensor with power and contains a computer system that controls the data acquisition process. There is a touch screen monitor used by the operator to set data acquisition parameters, start and stop recording, view the image as it is being acquired and review various engineering status indicators (power, temperature etc).The HyMap system has been designed to operate in aircraft that have standard aerial photo-ports. The angular width of the recorded image is 61.3 degrees or about 2.3 km when operating 2000m above ground level. Typically, the spatial resolution achieved with the HyMap is in the range 3 to 10 m. For the Ningaloo survey (3.5 m pixel size) the average survey altitude was about 1400m-1500m above ground with a swath width of 1.8 km.

Organization: Australian Ocean Data Network