Some winemakers are relying on a technique known as "precision viticulture" that involves collecting and mapping data to determine the best way to grow grapes. After gathering aerial images, practitioners form maps and integrate data such as the results of soil samples. "The whole process is guided by a GPS platform. The picking device is guided by GPS programmed for the particular site," said University of Aberdeen geography professor David Green. "The planting of vines is often done by GPS as well." Winemakers can use a geographic information system to analyze their vineyards and how they have changed over time.