Satellite Imagery
Monitoring and mapping the Earth’s constantly changing natural and cultural features is a challenge being met by images taken hundreds of kilometres away – in space. Detailed satellite images of the land are revolutionising mapping, environmental monitoring, emergency planning and ushering in the era of ‘precision agriculture’.
Value Added Reseller (VAR)
Terralink International is the authorised reseller and added value service provider of the Raytheon Australia and Australian Centre for Remote Sensing (ACRES) products. Terralink can directly obtain, process and provide satellite images such as IKONOS, SPOT and Landsat images.
Value Added Products (VAPs)
These products are derived from satellite images such as IKONOS, IKONOS stereo pairs, QuickBird, EROS and SPOT5. Orthorectified images, Digital Elevation Model (DEMs), contour lines and Normalised Difference Vegetation Index (NDVI) are examples of these derived products.
The Possibilities of Satellite Imagery
Unlike traditional photos of the land, usually captured by aerial photography for these purposes, satellite imagery is digital and multispectral. Satellite cameras capture infra-red and other bands in the light spectrum not recognised by the human eye. As different land and cultural features emit differing levels of various bands of the spectrum, analysis of satellite images can yield additional layers of data.
In creating the Land Cover Database for the NZ Government, Landsat 7 satellite images were analysed to assign one of seventeen land cover classifications to every hectare of the country. The Land Cover Database 2 is currently in production and includes an additional 27 land cover classes.
Satellite imagery is often used in conjunction with, or instead of, conventional aerial photography. Whilst planes flying at an altitude between 1 to 9 kilometres capture aerial photography, satellites orbit between 800 and 900 kilometres, thus capturing much larger scenes. An aerial photograph typically covers an area 5km by 7km or less, whilst a satellite imagery ‘scene’ can have boundaries as long as 185 kilometres.
Satellites are not yet able to capture the level of detail available in a high resolution aerial photograph but black and white resolution of 10 metres per pixel is available, making it ideal for mapping large rural areas. We use a mixture of satellite and aerial imagery to create maps for the Australian Federal Government. Read the Australian Federal Mapping case study or follow the link to see the seamless 1:250,000 digital map of Australia created from some of this work.
Archived Satellite imagery is also available for change detection analysis
Terralink International recently provided the stunning visuals for the Penguin New Zealand from Space 2 book which used a mixture of flat satellite images and satellite photos draped over 3D terrain models.