Level 3 Binning Operator

The user interface

I/O Parameters

Using the I/O Parameters tab, the input products can be set, as well as the target product's name and target directory. See the screenshot below.

• Add product(s) - Allows to add already opened products
• Add product file(s) - Allows to add specific files from the file system
• Add directory(s) - Allows to add directory and all products within
• Add directory recursively - Allows to add all products within a directory and the sub-directories

Filter

Two filters can be applied to limit the contents of the target product. See the screenshot below for the user interface for the filters.

Specify target region

The target region filter can be used to set the bounds of the target product. It is able to operate in four different modes:

1. the bounds of the target product are inferred by the bounds of all inputs products; that is, the smallest rectangular bounding box that contains all input products is being used.
2. the whole globe is used as region for the target product
3. the bounds of the target product are given by a user-provided WKT, according to this specification
4. the region of the target product can be drawn and entered using a dedicated world map component

Specify temporal filtering

The method that is used to decide which source pixels are used with respect to their observation time.

• NONE: ignore pixel observation time, use all source pixels.
• TIME_RANGE: use all pixels that have been acquired in the given binning period.
• SPATIOTEMPORAL_DATADAY: use a sensor-dependent, spatial "data-day" definition with the goal to minimise the tim between the first and last observation contributing to the same bin in the given binning period.
  The decision whether a source pixel contributes to a bin or not, is a function of the pixel's observation longitude and time
  Requires the parameter 'minDataHour'.
  For detailed information see the Spatial Data-Day page.

Configuration

Aggregator definitions

In the upper table the user can specify which data should be aggregated.
Using the plus button aggregation definition can be added. Depending on the selected aggregation method (AVG, MIN_MAX, ON_MAX_SET, PERCENTIL, ...) different parameters can be specified. Multiple aggregation definitions can be added. The edit button on the right hand side can be used to change to configuration of an existing aggregation definition. A description of the available aggregation algorithms is listed in a separate document: Aggregator Algorithms

The Intermediate Source Bands table has 3 columns: "Name", "Expression" and "Valid-Pixel Expression". It allows the user to define intermediate bands which are actually not part of the source products. These bands are defined by arithmetic band expressions. After being defined here, they are selectable as source band for the aggregators.
The 3rd column is optional and allows to specify a valid pixel expression. If not given, it will be generated by combining the valid pixel expression of all bands referenced in the expression. Setting it to true makes all pixels valid.

Valid expression and target height

Using the valid expression, the user can specify which values in the source products shall be considered. Thus, a boolean expression has to be set here. In the configuration of the example screenshot, only pixels that are not over land are considered.
The target height of the source product may be set, too; this value has direct influence on the spatial resolution.

Supersampling

As long as the area of an input pixel is small compared to the area of a bin, a simple binning is sufficient. In this case, the geodetic center coordinate of the Level 2 pixel is used to find the bin in the Level 3 grid whose area is intersected by this point. If the area of the contributing pixel is equal or even larger than the bin area, this simple binning will produce composites with insufficient accuracy and visual artifacts such as Moiré effects will dominate the resulting datasets.

The following figure illustrates this problem.

Level 2 grid (blue) and Level 3 grid (yellow)

The blue chessboard grid refers to the input data, the yellow one refers to the final Level 3 grid. As the figure clearly shows, single Level 2 pixels cannot be uniquely be assigned to single bins.

Supersampling parameter can be used to reduce or avoid the Moiré effect. The Moiré effect usually occurs when the spatial resolution used for the binning is similar to or smaller than the input pixel resolution. The supersampling subdivides every input pixel to n x n subpixels which all have the same values but different and unique geographical coordinates. This way, an input pixel may be distributed to more than one adjacent bin cell.