Hyperspectral surveys of Ningaloo Marine Park, Western Australia

Brief description

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.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Statement: The pixel size for the survey was nominated to be acquired at a size of 3.5m. Due to differences in ground speed of the aircraft, the actual pixel size may not be perfectly 3.5 during data acquisition. However during pre-processing all the geo located files are re-sampled to a 3.5 m pixel size and spacing. During a number of days of the survey and especially the last three days, the aircraft encountered extreme mechanical turbulence due to shear zones occurring at the flight altitudes over the land water boundary. This long term exposure to extreme vibration affected the liquid nitrogen cooled detector assembly (some internal structural parts were shaken loose) and resulted in some signal artifacts being introduced into the imagery. Most affected was the NIR spectrometer module. The VIS module, from which most of the reef mapping results will be derived, was unaffected.Process Step 1 Date: 2006-04-30T00:00:00 Description: Original Data Organisation Name: HyVista Corporation Role: processor Electronic Mail Address: hvc@hyvista.com Linkage: www.hyvista.com Protocol: WWW:LINK-1.0-http--linkProcess Step 2 Description: Conversion to 8 bit GeoTiff images Organisation Name: Australian Institute of Marine Science (AIMS) Position Name: Data Manager, AIMS Data Centre Role: processor Administrative Area: Queensland City: Townsville Mail Centre Country: Australia Delivery Point: Private Mail Bag 3 Electronic Mail Address: adc@aims.gov.au Postal Code: 4810 Linkage: www.aims.gov.au/adc Protocol: WWW:LINK-1.0-http--link Voice: +61 7 4753 4444Process Step 3 Description: Conversion to 24 bit GeoTiff images Organisation Name: Australian Institute of Marine Science (AIMS) Position Name: Data Manager, AIMS Data Centre Role: processor Administrative Area: Queensland City: Townsville Mail Centre Country: Australia Delivery Point: Private Mail Bag 3 Electronic Mail Address: adc@aims.gov.au Postal Code: 4810 Linkage: http://www.aims.gov.au/adc Protocol: WWW:LINK-1.0-http--link Voice: +61 7 4753 4444Statement: The 8 bit GeoTiff images are derived from the geospec mosaic images for each block. A reasonable colour mapping of the three bands in these images was applied and the images saved as 8 bit with colour table GeoTiff images. The 8 bit GeoTiff images can be opened in most image display programs and can be imported into OziExplorer. The colour range is limited and some loss of feature definition has occurred compared with the original 3 band 16 bit/band images.Process Step 1 Date: 2006-04-30T00:00:00 Description: Original Data Organisation Name: HyVista Corporation Role: processor Electronic Mail Address: hvc@hyvista.com Linkage: www.hyvista.com Protocol: WWW:LINK-1.0-http--linkProcess Step 2 Description: Conversion to 8 bit GeoTiff images Organisation Name: Australian Institute of Marine Science (AIMS) Position Name: Data Manager, AIMS Data Centre Role: processor Administrative Area: Queensland City: Townsville Mail Centre Country: Australia Delivery Point: Private Mail Bag 3 Electronic Mail Address: adc@aims.gov.au Postal Code: 4810 Linkage: www.aims.gov.au/adc Protocol: WWW:LINK-1.0-http--link Voice: +61 7 4753 4444Process Step 3 Description: Conversion to 24 bit GeoTiff images Organisation Name: Australian Institute of Marine Science (AIMS) Position Name: Data Manager, AIMS Data Centre Role: processor Administrative Area: Queensland City: Townsville Mail Centre Country: Australia Delivery Point: Private Mail Bag 3 Electronic Mail Address: adc@aims.gov.au Postal Code: 4810 Linkage: http://www.aims.gov.au/adc Protocol: WWW:LINK-1.0-http--link Voice: +61 7 4753 4444Statement: The 24 bit GeoTiff images are derived from the geospec mosaic images for each block. The data is identical to the .img files in that it is three bands of visible data (channels 15, 9, 3) stored as 16 bit integers. These images will not normally be viewable using simple image display software. Some GIS or image analysis software will be required to open them. They contain much more spectral information than the 8 bit GeoTiff files. The spatial resolution is the same. These files can be enhanced by altering the scaling of the individual bands whereas the 8 bit data has the colour mapping fixed.Process Step 1 Date: 2006-04-30T00:00:00 Description: Original Data Organisation Name: HyVista Corporation Role: processor Electronic Mail Address: hvc@hyvista.com Linkage: www.hyvista.com Protocol: WWW:LINK-1.0-http--linkProcess Step 2 Description: Conversion to 8 bit GeoTiff images Organisation Name: Australian Institute of Marine Science (AIMS) Position Name: Data Manager, AIMS Data Centre Role: processor Administrative Area: Queensland City: Townsville Mail Centre Country: Australia Delivery Point: Private Mail Bag 3 Electronic Mail Address: adc@aims.gov.au Postal Code: 4810 Linkage: www.aims.gov.au/adc Protocol: WWW:LINK-1.0-http--link Voice: +61 7 4753 4444Process Step 3 Description: Conversion to 24 bit GeoTiff images Organisation Name: Australian Institute of Marine Science (AIMS) Position Name: Data Manager, AIMS Data Centre Role: processor Administrative Area: Queensland City: Townsville Mail Centre Country: Australia Delivery Point: Private Mail Bag 3 Electronic Mail Address: adc@aims.gov.au Postal Code: 4810 Linkage: http://www.aims.gov.au/adc Protocol: WWW:LINK-1.0-http--link Voice: +61 7 4753 4444

Notes

Credit
Heyward, Andrew J, Dr (Principal Investigator)