How do I select data and start a GUI application (e.g. Sentinel Toolbox) via WEkEO portal?



Earth Observation Workbench alias Earth Observation Platform as a Service (EOPaaS) enables the user to:

  1. search datasets
  2. select data and view data 
  3. process data using GUI applications like SNAP/Sentinel toolbox or using one of the available processing service and download the outputs

Like other WEkEO services, EOPaaS/EO Wrokbench can be accessed from the drop-down list that appears by clicking on the <username> or by visiting in the browser. The landing page is shown below.



The page contains the following sections/tabs at the top:

  1. Explorer: It is the map based interface for a user to select, manage and use data and services
  2. Manage/Share: It lists the various groups that a user’s belongs to. Groups allow users to both communicate and share material within a selected number of peers
  3. Help: It provides tutorials and support materials on using the EOPaaS
  4. My Account: It provides an overview of a user’s account including profile information 

The various options/icons on the left side bar depends on the section/tab that is currently chosen.

Let's examine the steps for searching Level 2 OLCI Ocean Colour dataset and launching Sentinel Toolbox/SNAP to open/access one of the product from this dataset.

First click on the 'Search' icon search icon on the left panel in the explorer page. This brings up the dataset search panel. Placing the curson in the dataset search field brings up the list of all the available dataset. Alternatively type the few characters of the dataset to be searched for. In this example, 'olci ocean' is entered and two matching datasets (Full Resolution and Reduced Resolution) are available for selection as shown in the figure below.

Dataset search



Select Full Resolution dataset and optionally define a time range for the search as shown below and hit the search icon at the bottom.

OLCI dataset


This will bring up the data panel with 'Result' as the first tab of the panel.

OLCI Results


Now click on the 'Services' icon services icon to list all the available processing and application services available in the WEkEO portal. The figure below shows at least four different services with three of the them (Monteverdi, QGIS, SNAP) being GUI application services and one non-interactive processing service (s3rgb).

Select SNAP for this example. This will bring up the panel with fields based on OGC Web Processing Service (WPS). For the input field, drag one of the product from the 'Results' panel on to the field. Also enter keywords for label as appropriate. The completed workspace form will look like the one shown below.

SNAP launch


Now click on the 'Launch'/'Play' button at the bottom. This will bring a confirmation dialog informing the cost incurred for launching the service. EOPaaS uses the concept of coins which is a form of virtual currency to prompt fair usage of ICT resources. Click on 'Confirm' to launch the service.

Cost confirmation


'Jobs' panel showing the launched job with its associated job ID will be in focus.





In about a minute or few seconds, a new 'Go to GUI' icon Go2GUI will appear for the job as shown below.



Clicking on this 'Go to GUI' icon will launch a new browser tab for the SNAP application. Switch to the newly launched browser tab which will look like the figure below.

SNAP launch confirm


Click on 'OK' to launch the SNAP tool and view it from within the web browser.



Now open the previously selected input file from within the SNAP tool by clicking on folder icon Folder in the tool and navigating to the 'inDir'. The browser tab showing SNAP can be closed and reopened again from the 'Jobs' panel as before.


How do I select data and start a pre-configured processing service (e.g. RGB image generation) via WEkEO portal?

The steps are shown in the video below:

RGB image generation shown in the above video is based upon the "pconvert" tool that comes with sentinel-toolbox/SNAP. The syntax is:

pconvert [<options>] <file-1> [<file-2> <file-3> ...]

For image converstion, the following 2 options are generally used:
-f or --format <ext>. Possible values for <ext> are:
         png  - Portable Network Graphics image format
         jpg  - JPEG image format
         tif  - GeoTIFF image format
         bmp  - Microsoft Bitmap image format
-b or --bands <i> or <iR>,<iG>,<iB> or <i1>,<i2>,<i3>,<i4>...
     Specifies indices of the bands to be exported as a comma separated
     index list, 1 (one) corresponds to the first band.
     For image output, the number of bands should be 1 (greyscale) or
     3 (RGB), the default value is "-b 8,5,2" (optimized for MERIS).

In the video, "png" is entered for output format and "17" for red band, "6" for green band and "3" for blue band. Note that OLCI product has 21 bands (from 1 to 21). This is equivalent to calling pconvert from command line as follows:
pconvert -f png -b 17,6,3 {OLCI-product}