{"id":1776,"date":"2018-07-02T12:54:16","date_gmt":"2018-07-02T10:54:16","guid":{"rendered":"https:\/\/blogs.fu-berlin.de\/reseda\/?page_id=1776"},"modified":"2019-07-29T17:27:33","modified_gmt":"2019-07-29T15:27:33","slug":"s2-bulk-preprocessing","status":"publish","type":"page","link":"https:\/\/blogs.fu-berlin.de\/reseda\/s2-bulk-preprocessing\/","title":{"rendered":"Sentinel 2 Bulk Preprocessing"},"content":{"rendered":"

This section contains advanced techniques. Understanding these techniques is particularly relevant if you want to pre-process dozens of Sentinel 2 data in an identical way.
\nWe will create a graph in SNAP and then modify it to process all data automatically via the Graph Processing Tool (GPT)!<\/p>\n

Open SNAP and click on the graph builder icon \"\" in the Toolbar. You will see a new window pop up, which shows a standard graph (containing one Read <\/strong>and one Write <\/strong>node) in the upper area and some options in the lower area. Right click somewhere in the white area at upper window to add new nodes, i.e., processing steps, to the graph. Navigate to Add <\/em>> Raster <\/em>> Geometric <\/em>> Resample<\/em> to add an Resample <\/strong>and a Subset <\/strong>node (those are the steps we used in the above section):<\/p>\n

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Add new nodes to the graph via a right click<\/span><\/div>\n

Each processing step is visualized by a rectangle in the graph. You can drag those rectangles, or nodes, to whichever position you want with pressed left mouse button. Your graph should now look something like this:<\/p>\n

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Unconnected graph<\/span><\/div>\n

The individual nodes are not yet linked. If you rest the mouse pointer over the right edge of a rectangle, you will see a red arrow. Drag this arrow with pressed left mouse button to the next node in the following order:<\/p>\n

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Connected graph<\/span><\/div>\n

Next, click on the Read <\/strong>Node and load one of your ZIP-compressed Sentinel 2 scenes into the Source Product setting. This could take a short moment. Attention: <\/strong> From now on, it will always take a little while to switch back and forth between the processing nodes, as SNAP will process and read your data as virtual products in the background!<\/p>\n

Now either click through the tabs at the bottom of the Graph Builder window or through the rectangles at the top to set the following options for the Resampling<\/strong>, the Subset <\/strong>and the Write <\/strong>node (according to the settings made in the previous section):<\/p>\n