Student - June 25, 2009

SATELLITE SHOWS HOW THINGS GROW

Watching the grass grow by satellite. It sounds far-fetched, but it can be done. Researcher Lammert Kooistra and his colleagues at the Centre for Geo-Information provide free daily online updates on the growth of Dutch vegetation. Useful information - for farmers, for example, if they want to monitor their crops.

True, the web address (http://webgrs.wur.nl/ cgi/projects/sensorweb/pmapper/pmapper_GPP/map.phtml) could be a bit more user-friendly. But once you get on to the site, you can pick a day and one click will show you the growth map of the Netherlands for that day. Bright colours show how much carbon was stored at a particular spot that day – weather permitting of course, because the vegetation does need to be visible from space.

The Centre for geo-information’s plant growth website is an example of a dynamic web-mapping service for displaying constantly changing data on the internet. Web mapping is the latest trend in the science of remote sensing: studying planet earth from an ever- expanding army of satellites in space. ‘But until this decade most of the data was hidden away in databases and only accessible to a select group of specialists’, explains Kooistra. This is changing, and both a new science and a new market have grown up around making the data available to a broader public. The best-known example is of course Google Earth.

One of the new developments is linking various sources of sensor data with a geographical information system (GIS). Kooistra’s plant growth map links satellite data with weather data from the Dutch meteorological institute KNMI. The result is a straightforward and accessible product, which researchers from the Centre for Geo-Information have been working on. ‘We want to link different types of sensor information and make the resulting maps available online, preferably in real time.’ And all in a standardized format in an open source environment. An advantage of this is that other users such as farmers can easily download the information for use in their own business. The growth map is an example. ‘The point is that you can process all kinds of data in a standardized way for real time applications. At present we have focused on the agricultural sector. But in theory you can link up data from all kinds of different sensor networks.’

Mapping plant growth from outer space is nothing new. NASA has been doing it for years. ‘But NASA does it on a global scale and doesn’t use local sensors, so there is much less detail’, says Kooistra. His plant growth map has a resolution of 250 metres, which is as sharp as the satellites can get it.

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