09 October 2014
A recent Comment in Nature (Nature, 513, 30-31; 2014) argued that freely available satellite imagery will improve science and environmental-monitoring products. "Although we fully agree that greater open access and sharing of satellite imagery is urgently needed, this plea neglects a crucial component of land cover generation, i.e. the data required to calibrate and validate these products," says Linda See, senior researcher in IIASA's ESM Program, in Nature Correspondence.
At present, remotely-sensed global land cover is not accurate enough for monitoring biodiversity loss and ecosystem dynamics or for many of the other applications for which baseline land cover and change over time are critical inputs. When Sentinel-2 comes online, it will be possible to produce land cover maps at a resolution of 10 m. Although this has incredible potential for society as a whole, these products will only be useful if they represent the land cover more accurately than the current products available. "To improve accuracy, more calibration and validation data are required. Although more investment is clearly needed in ground-based measurements, there are other, complementary solutions to this problem," says Steffen Fritz, leader of a major ERC project which is addressing these issues.
Not only should governments and research institutes be urged to share imagery, they should also share their calibration and validation data. Some efforts have been made by GOFC-GOLD in this direction but there is an incredible amount of data that remains locked within institutes and agencies. The atmospheric community shares their data much more readily than the Earth Observation (EO) community and would only benefit by doing so. Secondly, with the availability of very high resolution satellite imagery, crowdsourcing of calibration and validation data has real potential for vastly increasing the amount of data available to improve classification algorithms and the accuracy of land cover products. Geo-Wiki is only one example of a growing community of crowdsourcing applications that aim to improve the mapping of the Earth’s surface. Tapping into these communities with a coordinated effort will only benefit EO in the long run.
Last edited: 09 October 2014
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