Exercise 3.1: Filter

The collection contains all imagery ever collected by the sensor. The entire collections are not very useful. Most applications require a subset of the images. We use filters to select the appropriate images. There are many types of filter functions, look at ee.Filter... module to see all available filters. Select a filter and then run the filter() function with the filter parameters.

We will learn about 3 main types of filtering techniques

  • Filter by metadata: You can apply a filter on the image metadata using filters such as ee.Filter.eq()ee.Filter.lt() etc. You can filter by PATH/ROW values, Orbit number, Cloud cover etc.
  • Filter by date: You can select images in a particular date range using filters such as ee.Filter.date().
  • Filter by location: You can select the subset of images with a bounding box, location or geometry using the ee.Filter.bounds(). You can also use the drawing tools to draw a geometry for filtering.

After applying the filters, you can use the size() function to check how many images match the filters.

Watch this video:


The code is available in this repository under Module3/Exercise1

Your task after the exercise

Modify the script of exercise 3.1 in such a way that:

  • it uses the location of your own area of interest
  • it shows the band combination R = NIR, G = RED, B = GREEN
  • it only shows results for the Sentinel 2A satellite without Sentinel 2B. For this you need to add a filter. Hint 1: use the 'SPACECRAFT_NAME' metadata property. Hint 2: Use the ee.Filter.eq() filter

Last modified: Monday, 19 July 2021, 3:38 PM