NDVI-GE - from Saccess to vegetation index maps on Google Earth
Focus-on-Nutrients (Greppa Näringen (www.greppa.nu) is a programme for improving the management of fertilizers at the farm level. During 2010 a new Focus-on-Nutrients advisory module for farmers were developed on precision agriculture. Advisory modules are free for farmers that take part in the programme. One of the tools that are included in that module is NDVI (normalized difference vegetation index) maps available for display as overlays in Google Earth. These NDVI maps were generated from satellite scenes from 2009 available on Saccess, the national Swedish satellite image database (saccess.lantmateriet.se). Ortho-rectified SPOT 5 satellite scenes from late May to early July were used. NDVI variation maps (as colour images showing NDVI variation on arable land only – not covering other land use) were generated by a tedious manual process. This process generated images suitable for overlay in Google Earth (example map shown in figure 1). The primary use of the NDVI maps is to serve as a means for discussion on within-field variation of crop growth. Both the farmers and the advisors have appreciated the possibility to get a quantitative measure on the variation of crop growth, albeit an image with relative values.
Figure 1. The tool will generate NDVI maps for display in Google Earth from satellite scenes that can be downloaded from Saccess. The maps should only cover arable land (transparent on other land use).
Many users now ask for new updated NDVI maps. Therefore, it would be a big advantage if those interested could create such maps themselves in an easy manner. The goal in this project is to develop a simple and free software tool – NDVI-GE – that can generate NDVI images for display in Google Earth from satellite scenes, e.g. downloaded from Saccess. The software tool will be part of the Focus-on-Nutrients precision agriculture module, but it will be free for any user.
Mats Söderström, Swedish University of Agricultural Sciences, Dept of Soil & Environment,
Box 234, SE-532 23 Skara, Sweden. E-mail: email@example.com
13 maj 2011