Friday, January 11, 2008

satellite imagery...

Recently on homepage, producer Amy Spear took a look at Satellite imagery and how this could potentially help to monitor and protect the environment...

Satellite imagery is an amazing technology used by a number of organisations – as they say a picture paints a thousand words and there are many benefits to using this technology.
She spoke with David Moore, the managing director of Terranean Mapping Technologies and Len Banks, Executive Director for Scientific Services in the NSW Department of Environment and Climate Change.
To begin with, David Moore explains just how a satellite image is taken:
“Remote sensing satellites take images of the earth and it’s like having a big scanner orbiting the earth at about 700km above the service and scanning lines backwards and forwards and measuring the visible light and infrared from the earth’s surface. That is transmitted back down to the earth to a ground receiving station and put together into an image which looks like an aerial photograph covering a very large area of the earth’s surface.”
There are certainly many benefits for analysing the environment…
“Mapping the environment and land use is a big one and, for example, a local counsel who is doing their planning not only wants to know where the native forest and native vegetation is now, but they want to put that into a historic context and go back and see how it was in the 1970s and see the changes that have occurred since then. There’s a nationwide program that is being run where every two years they actually measure the number of trees or the amount of woody vegetation over the whole country. They can calculate from the changes in that how much extra CO2 has been released from the tree clearing or taken back in by regeneration so that they can actually account for the changes in CO2. Also they’re using them for monitoring tree clearing – different states have different tree clearing legislation and using satellite images from two different times (before they brought the law in and after they brought the law in) they can see very clearly where trees are being cut down. It’s very good for monitoring in that sense.”
David’s background is in ecology – so while it’s interesting to see the way landscapes fit together and interact, he says it can also be very sobering to see the impacts of industrialisation from 700km in the air. He believes that these images, particularly in historical context, could be more readily available to the public.
So what can we expect from this technology in the future?
“Some of the things that are really driving this are getting quick turn around images – so people are now looking at the idea of putting a geostationary satellite up which is always looking down at the same time and just sending the images down so you’ll be able to see people driving along in their cars and get information in real time.
The other thing they’re looking at is measuring the entire spectrum in very great detail so that you can get very subtle differences in plant health, different soil types and geology and be able to do a lot more detailed scientific analysis of things.
As every one or two years goes past there’s a new satellite launched with even higher resolution of detail so we get can closer and closer to centimetre type scales of resolution.”
The NSW Department of Environment and Climate Change, in conjunction with the rest of the State Government, is one of the organisations making full use of this technology. Len Banks, the executive director for scientific services in this department, explains why it is an important tool in the field.
“The NSW Department of Environment and Climate Change uses satellite imagery so that we can get a digital representation of the landscape. The satellites pick up different reflections from the various features of the landscape. So whether they be trees or soil or water or buildings and so on, that builds up a picture of those different features. So being digital data, we can analyse the various components that come through in an image to measure, for instance, areas of particular density or features so that we can combine that then with other digital data like soils information or roads or planning decisions and approvals that might be spatially referenced and therefore in a digital format.
We can produce multiple layers of information about the landscape so that we can then compare differences over time or make investment decisions about where’s the best place to make changes in the landscape.”

There are, of course, a range of reasons this technology can be used. One example that is becoming apparent at the moment, is the use of imagery to capture land clearing crimes.
“One of the uses we’re putting the imagery to – we use it for a whole range of reasons – but an important one is to identify areas where there has been a change in vegetation. The satellite will tell us where there has been tree loss or perhaps even regeneration. That area of tree loss… could be through fire or land clearing or trees dieing from drought for instance. It tells us where people on the ground can go and check it against land clearing approvals and see where investigations need to take place. So it is a useful tool in pointing those investigations in the right direction and making those investigations much more efficient.”
Len says the NSW government is moving forward from the LandSat Imagery, which gives a resolution of about ten metres, to getting images through the Spot 5 satellites at about 2.5 metres squared. So now instead of seeing clumps of trees, they’ll be seeing individual ones on the landscape.
It will be interesting to see what is spotted in the future by this incredible technology.

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