Archive for February, 2009
VICTORIA BUSHFIRES UPDATES WITH HIGH-RESOLUTION SATELLITE EROS-B
Thursday, February 26th, 2009Imagery over fires is being donated by Apogee and our associates to assist the firefighters in Victoria
Apogee tasked ImageSat International EROS-B high-resolution satellite to capture the affected area between the 14th and the 19th of February.
EROS satellites are high performance, light, highly manoeuvrable high-resolution observation satellites. The satellite’s light weight and rigidity allows a quick and stable re-pointing of it’s line of sight allowing fast manoeuvring between targets.
The images below have been acquired with EROS-B, the second of the EROS constellation. The camera system produces an image resolution of 70cm at nadir which allows accurate feature detection.
Overview of EROS-B acquisition over the burnt area.
Sub-metre resolution satellites make it possible to produce accurate assessments of the damage and assist the reconstruction effort.
South of the Bunyip State Park with EROS-B
The Town of Waterford Park spared by the blaze
A property destroyed by the fire which has spread along the highway
Fire scars after the powerful blaze jumped out of the forest.
TERRASAR-X OVER VICTORIA BUSHFIRES
Thursday, February 19th, 2009Imagery over fires is being donated by Apogee and our associates to assist the firefighters in Victoria
Apogee has tasked the new generation Radar satellite TerraSAR-X to acquire data over the severe bushfires in Victoria. This satellite can image an area twice a day through clouds and smoke at high resolution, where data acquired from the numerous optical satellites can not be captured until clouds part. The MODIS image shown below was acquired on the same day as the TerraSAR image showing the cloud cover at the time.
MODIS image from the 11th of February 2009.
Observation of the bushfires was made difficult due to extensive cloud cover as shown in the MODIS image above.
A ScanSAR image was acquired on the 11th of February 2009 and a composite image has been produced by merging a second ScanSAR image from the extensive archive TSX is capturing as a continuous background mission.
Comparing the post-fire acquisition to the archive data from the 20th of April 2008 improves the extraction of relevant information on fire impact.
A ScanSAR image has been acquired on the 11th of February 2009 and a composite image has been processed with archive data from the 20th of April 2008 to assess changes before and after the disaster. Changes can be seen in red. Slopes facing the radar sensor are brighter than the back slope of hills. This characteristic is enhanced due to lower leaf density in areas of forest where tree canopy has burnt.
The above picture is an extract of this image composition over the town of Marysville in which most of the infrastructures have been destroyed by the fire. The post-fire data registers a significant increase in backscatter magnitude compared to the archive data where houses have been destroyed due to the spread of debris and defoliation. This appears as distinct red areas within the township.
The town of Buxton in comparison, which has escaped the same level of destruction, is clearly distinguished by houses appearing white and indicating that their recorded radar reflection is unaltered from the previous year’s acquisition. This example shows how powerful the use of TerraSAR-X can be when no other visual assessment of the situation is possible due to heavy smoke and clouds.
The above image shows the Bunyip State park seen through clouds and smoke. The bright red area shows extensively burnt forest caused by the increased backscatter post-fire. This is due to the absence of leaves allowing the radar signal to interact with the bare ground and stems of the trees. On the slopes facing away from the radar signal this effect is not as evident.
Victoria Fires Satellite Imagery update
Tuesday, February 17th, 2009Imagery over fires is being donated by Apogee and our associates to assist the firefighters in Victoria
Apogee tasked the Surrey Satellite Technology Ltd. Disaster Monitoring Constellation (DMC), which captured the affected area on the morning of Friday, the 13th. The image below shows a False Colour Composite of the burnt area.
Victoria Bushfires
Wednesday, February 11th, 2009Satellite views of Victoria’s Bushfires show the immense extent of Australia’s worst natural disaster. Images from the MODIS sensor and the Surrey Satellite Technology Ltd. Disaster Monitoring Constellation are shown below.
MODIS image acquired on Saturday, 7th January 2009, at 250m spatial resolution shows large smoke plumes over Victoria.
The MODIS image acquired on Saturday the 8th has extensive cloud preventing a clear view of the extent of the smoke plume. The yellowish colour of the smoke however can be discriminated from the white cloud.
Apogee tasked the Surrey Satellite Technology Ltd. Disaster Monitoring Constellation (DMC), which captured the affected area at 30m resolution on the morning of Monday, the 10th, with its 650km wide imaging capability. Cloud cover obscures the lower half of the image but smoke extending in a North-Westerly direction can be seen for many of the still active fires.
Zoom over the Cathedral Range State Park area showing active fires.
